Aliphatic polyester block copolymer blends for hydrolytically degradable pressure sensitive adhesives

Abstract

This disclosure generally relates to the design of renewably sourced, readily degradable pressure-sensitive adhesives (PSAs) that exhibit tunable adhesion properties is beneficial to address sustainability concerns associated with traditional, fossil fuel-derived counterparts. More generally, aliphatic polyester triblock copolymers of poly(L-lactide)-block-poly(γ-methyl-ε-caprolactone)- blockpoly(L-lactide) (LML) and blends with renewable tackifier in PSA formulations are discussed. More particularly, effects of tackifier, composition, and processing history on microstructural, thermal, mechanical, and adhesive properties of the PSAs are disclosed. Specifically, LML-based PSAs are hydrolytically degradable into water soluble or dispersible compounds at 45°C under basic conditions within 30 days, offering a sustainable end-of-life scenario via its potential in composting makes for an ideal and sustainable alternative for commercial acrylic incumbents.

Description

ALIPHATIC POLYESTER BLOCK COPOLYMER BLENDS FOR HYDROLYTICALLY DEGRADABLE PRESSURE SENSITIVE ADHESIVESCROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of U.S. Application No. 63 / 693,510 filed September 11, 2024, and U.S. Application No. 63 / 767,056 filed March 5, 2025, the entirety of both applications are incorporated herein by reference.TECHNICAL FI ELD

[0002] This disclosure generally relates to degradable polyester based copolymers, articles containing the polyester based polymers, and methods of making the polyester based copolymers.BACKGROUND

[0003] Pressure-sensitive adhesives (PSAs) represent an important class of adhesives that are widely applied as tapes, labels, and sticky notes. Ideal PSAs should readily adhere to surfaces of interest over a short period (seconds) of time under mild pressure, exhibit high shear resistance during application, and be easily removed without residue. In this context, PSAs are commonly characterized by two potentially conflicting properties, adhesion to a wide variety of surfaces and cohesion to hold together during stress, that are intrinsically related to their viscoelastic properties. During the bonding process, adhesion of PSAs on a substrate normally requires viscous liquid-like behavior and wettability to establish a large area of contact and maximize interactions (e.g., van der Waals) with the substrate. However, to resist deformation once adhered, and exhibit desired removability after an application, PSAs should also be elastic and embody strong cohesive forces with effective energy dissipation during debonding. Polyacrylates, natural rubber, and styrenic block copolymers are typically used as PSAs and represent the three main classes of contemporary PSAs. Among them, tackified styrenic copolymers with a microphase- separated ABA triblock architecture are of particular interest due to their tunable mechanical properties and competitive cost.

[0004] ABA styrenic triblock copolymers are typically comprised of two glassy / minority "A" polystyrene end-blocks and a rubbery / majority "B" mid-block that typically makes up 70-90 weight percentage (wt%) of the copolymers. The "B" mid-block normally possesses a glass-transition temperature (Tg) well below room temperature and forms a soft, rubbery matrix with a high level of wettability on desired surfaces. Conversely, the chemically incompatible "A" end-blocks are high Tgand form glassy,microphase-separated hard domains that act as physical cross-links to provide cohesive strength and creep resistance. Poly(styrene)-block-poly(isoprene)-block-poly(styrene) (SIS) and poly(styrene)-block- poly(butadiene)-block-poly(styrene) (SBS) are two commercialized examples used in PSAs. Such styrenic copolymers are often blended with tackifiers (e.g., low molar mass compounds with Tg around room temperature) that selectively swell the rubbery matrix to effectively dilute mid-block entanglements, reducing the elastic modulus and thereby enhancing adhesion with the substrate, while also often reducing cost.

[0005] Unfortunately, fossil resource derived styrenic copolymers and acrylics exhibit poor degradability, primarily due to their all carbon-carbon bond backbones. As a consequence, adhesive residues can accumulate in the environment and waste recycling facilities, creating long-lived plastic waste and difficulties in waste recycling.SUMMARY

[0006] Exemplary embodiments relate to a composition comprising: a triblock copolymer comprising: poly(L-lactide)-block-poly(y-Methyl-e-caprolactone)-blockpoly(L-lactide) (LML); and a tackifier. This embodiment or other embodiments can provide for the composition comprises between 15 and 45 wt% of the tackifier. This embodiment or other embodiments can provide for the composition comprises between 55 and 85 wt% of the triblock copolymer. This embodiment or other embodiments can provide for the triblock copolymer is the reaction product of Tin (II) 2-ethylhexanoate, L-lactide, and a macroinitiator containing y-Methyl-e-caprolactone. This embodiment or other embodiments can provide for an construction comprising: a triblock copolymer comprising: poly(L-lactide)-block-poly(y- Methyl-e-caprolactone)-blockpoly(L-lactide) (LML); and a tackifier and a substrate. This embodiment or other embodiments can provide for the composition and the substrate together have a total thickness of about 20-lOOpm. This embodiment or other embodiments can provide for the composition has a first thickness and the substrate has a second thickness and a ratio of the first thickness to second thickness is about 1:1. This embodiment or other embodiments can provide for the substrate has a first side and a second side opposite the first side and the substrate is a face film. This embodiment or other embodiments can provide for the construction to exhibit a peel adhesion, when the composition is coated onto the face film, of greater than 0.5 N / cm when tested in accordance with PSTC:101 at a rate of 305mm / min when the construction is applied to stainless steel. This embodiment or other embodiments can provide for the construction to exhibit a peel adhesion, when the composition is coated onto the face film, of greater than 2.2 N / cm when tested in accordance with PSTC:101 at a rate of 305mm / min whenthe construction is applied to stainless steel. This embodiment or other embodiments can provide for the construction to exhibit a loop tack adhesion, when the composition is coated onto the face film, of greater than 0.18 N / cm when tested in accordance with ASTM:D1695 at a rate of 305mm / min when the construction is applied to stainless steel. This embodiment or other embodiments can provide for the construction to exhibit a loop tack adhesion, when the composition is coated onto the face film, of greater than 1.1 N / cm when tested in accordance with ASTM:D1695 at a rate of 305mm / min when the construction is applied to stainless steel. This embodiment or other embodiments can provide for the construction to exhibit a shear strength when the composition is coated onto the face film, of greater than 240 hours when tested in accordance with to PSTC:107 when the construction is applied to stainless steel. This embodiment or other embodiments can provide for the face film is selected from the group consisting of: polyolefins, polyvinyl chloride, polyethylene terephthalate, polystyrene, polyurethane, polymethacrylate, polycarbonate, paper, cardboard, and combinations thereof. This embodiment or other embodiments can provide for a liner, wherein the substrate has a first side and a second side opposite the first side, and the liner has a first face and a second face opposite the first face, and the composition is located between the second side of the substrate and the first face of the liner. This embodiment or other embodiments can provide for the liner is selected from the group consisting of: paper, treated paper, polymer film, and treated polymer film. This embodiment or other embodiments can provide for a release liner located longitudinally below the composition and longitudinally above the first face of the liner.

[0007] Other exemplary embodiments relate to a method comprising: providing a composition comprising a triblock copolymer comprising: poly(L-lactide)-block-poly(y-Methyl-e-caprolactone))- blockpoly(L-lactide) (LIX / IL) and a tackifier; coating the composition onto a substrate resulting in a construction; and adhering the substrate to an article. This embodiment or another embodiment can provide for dissolving the composition into a solvent prior to coating onto the substrate; removing the solvent after coating onto the substrate resulting in a dried construction; annealing the dried construction at a temperature of between 150-200°C for at least one hour; and quenching the dried construction in less than 5 minutes to a temperature below 25°C. This embodiment or another embodiment can provide for annealing a second time the dried construction after the quenching step, at a temperature of between 90-160°C for at least five minutes; and quenching the dried construction a second time, in less than 3 minutes to a temperature below 25°C.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a graphical representation of the1H-N MR spectra of poly(y-Methyl-e-caprolactone) (PyMCL), in deuterated chloroform (CDCI3), with 64 scans.

[0009] Figure 2 is a graphical representation of the1H-NMR spectra of poly(L-lactide)-block-poly(y- methyl-e-caprolactone)-blockpoly(L-lactide) (LML) (76.6, 0.27) in CDCI3, with 64 scans.

[0010] Figure 3 is a graphical representation of the13C-NMR spectra of PyMCL (top) and LML (bottom) with magnified carbonyl region.

[0011] Figure 4 is a graphical representation of the Size Exclusion Chromatography (SEC) trace of the LML triblock of the differential refractive index versus the elution time in minutes.

[0012] Figure 5 is a graphical representation of the1H NMR spectra of alkyne-ML and LML / ML blends.

[0013] Figure 6 is a graphical representation of the SEC traces of alkyne-ML(38.8, 0.26) and LML / ML blends.

[0014] Figure 7 is a graphical representation of1H-NMR spectras of a,a'-dibromo-p-xylene (bottom) and as-prepared a,a'-diazido-p-xylene linker (top) in CDCI3, 400 MHz, 16 scans, dl = 1 s.

[0015] Figure 8 is a graphical representation of the1H-NMR spectra of alkyne-terminated PyMCL(31.1). CDCI3, 400 MHz, 64 scans, dl = 10 s.

[0016] Figure 9 is a graphical representation of the1H-NMR spectra of alkyne-ML(38.8, 0.26). CDCI3, 400 MHz, 64 scans, dl = 10 s.

[0017] Figure 10 is a graphical representation of the SEC traces of alkyne-terminated PyMCL(33.1) and alkyne-ML(38.8, 0.26).

[0018] Figure 11 is a graphical representation of the SEC traces of ML(37.5,0.22) without alkyne termination before and after copper-catalyzed alkyne-azido cycloaddition reaction.

[0019] Figure 12 is a graphical representation SEC traces of 25 wt% LML blends before and after second copper-catalyzed alkyne-azido cycloaddition reaction.

[0020] Figure 13 is a graphical representation of a series of1H-NMR spectra after solvent casting LML (76.6, 0.27) (top), solvent casting and first annealing at 170°C (middle), and solvent casting, first annealing at 170°C as well as second annealing 100°C (bottom).

[0021] Figure 14 is a graphical representation of the tetrahydrofuran (THF) SEC traces of LML (76.6, 0.27) after solvent casting (bottom); solvent casting, first annealing at 170 for 60 minutes and then rapid cooling to room temperature (middle); solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes and rapid cooling to room temperature (top; vertically shifted for clarity).

[0022] Figure 15 is a graphical representation of small-angle X-ray scattering (SAXS) patterns of LML (76.6, 0.27) and blends of LML(76.6, 0.27) with 20-43 wt% tackifier after solvent casting (vertically shifted for clarity).

[0023] Figure 16 is a graphical representation of SAXS patterns after processing and its effects on the microstructure of the blend of LML (76.6, 0.27) with 33 wt% tackifier.

[0024] Figure 17 is a graphical representation of SAXS patterns of alkyne-ML(38.8, 0.26) and LML / ML blends after solvent casting.

[0025] Figure 18 is a graphical representation of differential scanning calorimetry (DSC) traces of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting (first heating, 10°C / min; vertically shifted for clarity).

[0026] Figure 19 is a DSC traces of alkyne-ML(38.8, 0.26) and LML / ML blends after solvent casting, (first heating, 10 °C / min; vertically shifted for clarity).

[0027] Figure 20 is a set of images from atomic force microscopy (AFM) showing adhesion contrast and water contact angle measurement of blend of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting ((a) and (c) ), and solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature ((b) and (d) ).

[0028] Figure 21 is a graphical representation of SAXS patterns of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature (vertically shifted for clarity).

[0029] Figure 22 is a graphical representation of DSC traces of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature (vertically shifted for clarity).

[0030] Figure 23 is a graphical representation of differential scanning calorimetry (DSC) traces of LML (76.6, 0.27) (bottom), tackifier (top, denoted Sylvalite 2E 80HP), and blends of LML (76.6, 0.27) with 20- 43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature (vertically shifted for clarity).

[0031] Figure 24 is a graphical representation of DSC traces of a blend of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 0-30 minutes, and rapid cooling to room temperature (vertically shifted for clarity).

[0032] Figure 25, at (a) is a graphical representation of master curves for the storage modulus (G') and loss modulus (G") of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, firstannealing at 170°C; while (b) shows viscoelastic windows analysis to guide the design of PSAs based on itsG' and G".

[0033] Figure 26 is a graphical representation of master curves for the storage modulus (G') and loss modulus (G") of (a) LML (76.6, 0.27) and (b) blend of LML (76.6, 0.27) with 20 wt% tackifer after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature.

[0034] Figure 27 is a graphical representation of master curves for the storage modulus (G') and loss modulus (G") of (a) LML (76.6, 0.27) and blends of LML (76.6, 0.27) with (b) 20 wt%, and (c) 33 wt% tackifier after solvent casting. The Dahlquist criterion (G' < 0.3 MPa at 1 rad / s) is marked by dashed lines.

[0035] Figure 28 is a graphical representation of a viscoelastic window analysis at 20°C of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-33% tackifier after only solvent casting.

[0036] Figure 29 is a graphical representation of master curves for the (a) storage modulus (G') and (b) tan (6) of alkyne-ML(38.8, 0.26) and 75 wt% LML blends after solvent casting.

[0037] Figure 30 is a graphical representation of master curves for the storage modulus (G') and loss modulus (G") of (a) 25 wt% LML blend and (b) 50 wt% LML blend after solvent casting.

[0038] Figure 31 is a graphical representation of (a) 180° peel adhesion properties and (b) loop tack adhesion properties on stainless steel substrates of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature.

[0039] Figure 32 is a graphical representation of tensile curves of alkyne-ML(38.8, 0.26) and LML / ML blends after solvent casting. Extended at 305 mm / min, with the break point indicated by x.

[0040] Figure 33 is a graphical representation of (a) 180° peel adhesion properties and (b) loop tack adhesion properties on stainless steel substrates of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, or solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature.

[0041] Figure 34 is a graphical representation of the 180° peel adhesion properties on stainless steel substrates of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at different temperatures for 60 minutes, and rapid cooling to room temperature are shown.

[0042] Figure 35 is a graphical representation of the 180° peel adhesion properties on stainless steel substrates of blends of poly(L-lactide)-block-poly(y-methyl-e-caprolactone)-block-poly(L-lactide) (LML) and poly(D,L-lactide)-block-poly(y-methyl-e-caprolactone)-block-poly(D,L-lactide) (aLML) (78.5,0.22) with20-43 wt% tackifier after solvent casting, or solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature.

[0043] Figure 36 is a graphical representation of the shear resistance on stainless steel substrates of blends of LML (76.6, 0.27) and a LML (78.5, 0.22) with 20-43 wt% tackifier after solvent casting, or solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature.

[0044] Figure 37 is a graphical representation of (a) 180° peel adhesion properties and (b) shear resistance properties on stainless steel substrates of alkyne-ML(38.8, 0.26) and LML / ML blends after solvent casting with additional 20 wt% tackifier. All of the 180° peel adhesion tests were performed at the rate of 305 mm / min. Inserted digital images in (a) showed the stainless steel substrates surface after the 180° peel adhesion tests.

[0045] Figure 38 is a graphical representation of aging of 180° peel adhesion properties on stainless steel substrates of blend of LML (76.6, 0.27) with 33 wt% tackifiers after solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature.

[0046] Figure 39 is a graphical representation of DSC traces reflect aging of blend of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature.

[0047] Figure 40 is a graphical representation showing the aging of 180° peel adhesion properties on stainless steel substrates of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature.

[0048] Figure 41 is a graphical representation of 180° peel adhesion properties on PET and HDPE substrates of blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature.

[0049] Figure 42 is a graphical representation of Shear resistance properties on stainless steel substrates of alkyne-ML(38.8, 0.26) and LML / ML blends after solvent casting with additional 20 wt% tackifier, first annealing at 170 °C for 60 minutes, second annealing at 100 °C for 5 minutes, and rapid cooping to room temperature.

[0050] Figure 43 is a graphical representation of 180° peel adhesion properties on stainless steel substrates of alkyne-ML(38.8, 0.26) and LML / ML blends after solvent casting with additional 20 wt% tackifier, first annealing at 170 °C for 60 minutes, second annealing at 100 °C for 5 minutes, and rapid cooping to room temperature. All of the 180° peel adhesion tests were performed at the rate of 305 mm / min.

[0051] Figure 44 is a graphical representation of a SEC trace of the LML / ML blends synthesized in one set of sequential ring-opening polymerizations (route 3).

[0052] Figure 45 is a graphical representation of hydrolytic degradation studies in 1 M NaOH aqueous solution at 45°C of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature.

[0053] Figure 46 is a graphical representation of hydrolytic degradation studies in 1 M NaOH aqueous solution at 45°C of (a) PET films and (b) Sylvalite tackifier powders.

[0054] Figure 47 is a graphical representation of hydrolytic degradation studies in 1 M NaOH aqueous solution at 45°C of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting (square); solvent casting, first annealing at 170°C for 60 minutes and then rapid cooling to room temperature (circle); solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes and rapid cooling to room temperature (triangle).

[0055] Figure 48 is a graphical representation of a hydrolytic degradation study in 1 M NaOH aqueous solution at 45 °C of tackified PSA (20 wt% tackifier) from LML / ML blends with 50 wt% LML after solvent casting. The total organic carbon (TOC) content is the ratio of measured organic carbon in the aqueous solutions to the theoretical carbon content of the blends. The data points and error bars represent median and range for triplicate experiments, respectively.

[0056] Figure 49 is a graphical representation of hydrolytic degradation studies in 1 M NaOH aqueous solution at 45 °C of tackified PSA (20 wt% tackifier) from (a) alkyne-ML(38.8, 0.26), (b) LML / ML blends with 25 wt% LML and (c) LML / ML blends with 75 wt% LML after solvent casting.Definitions

[0057] As used herein, the term "construction", "laminate" or "multilayer" means, at least one adhesive coated material, generally with one or more additional layers. Non-limiting examples of such layers to make up the construction, laminate, or multilayer include protective layers, spacing layers, adhesive layers, optical component-containing layers, metallic layers, barrier layers, release liners, tie coat layers, clear layers, color layers, white layers, reflective layers, fluid transfer layers, strength promoting layers, topcoats, print receptive layers, print containing layers, indicia layers, functional layers, and the like as well as combinations thereof. The resultant construction, laminate, or multilayer laminate described herein can be used for a variety of applications including, but not limited to, graphicsapplications, such as automobile and architectural wraps; reflective applications, such as road and traffic signs, trains and other commercial vehicles, etc.; and label and packaging applications.

[0058] As used herein, the term "substrate" refers to any material in which adhesive can be coated or otherwise deposited. Common substrates can include, but are not limited to, polymeric films, cardboard, paper, combinations thereof, and other similarly situated materials.DETAILED DESCRIPTION

[0059] In light of the forgoing, it is important to develop sustainable alternative PSAs with comparable performance, to address challenges such as those described hereinabove associated with traditional, fossil fuel-derived counterparts. The disclosure herein discusses compositions including poly(L-lactide)-block-poly(y-methyl-e-caprolactone)-block-poly(L-lactide) (LIX / I L) aliphatic polyester triblock copolymers and a tackifier, as well as synthesis of poly(L-lactide)-block-poly(y-methyl-e- caprolactone)-block-poly(L-lactide) (LIX / I L) aliphatic polyester triblock copolymers and their application in PSAs when blended with tackifier.

[0060] ABA triblock polyester block copolymers can often be derived from renewable feedstocks that are typically susceptible to hydrolytic degradation. It was unexpectedly discovered that ABA triblock polyester block copolymers provide degradable adhesives that exhibit desirable PSA characteristics. For instance, poly(lactide)-blockpoly(menthide)-block-poly(lactide), poly(lactide)-block-poly(P-methyl-6- valerolactone)-block-poly(lactide), poly(L-lactide)-block-poly(e-decalatone)-blockpoly(L-lactide), poly(lactide)-block-poly(pentadecyl-caprolactone)-blockpoly(lactide), and many other poly(a lkyl-6- lactone)-based triblock copolymers were synthesized with well-defined chemical compositions and molar masses, on-demand degradability, as well as excellent mechanical properties, demonstrating enticing potential for applications as sustainable PSAs.

[0061] While many efforts have been taken to expand the chemical and architectural scope of polyester block copolymers, it is important to note that the processing history imposed on any chosen system can also contribute crucially to adhesion properties. For instance, hot-melt coating, solvent coating, and post-coating annealing processes of SIS-based PSAs were found to result in distinct microstructures, rheological properties, and varying adhesion performance. The influence of processing routines on the properties of polyester-based PSAs have not been widely investigated in detail.

[0062] Both y-methyl-e-caprolactone and L-lactide monomers are readily derived from renewable feedstocks, and LMLs can be readily biodegraded via enzymatic hydrolysis or under simulated industrial composting conditions. This LML-based PSA provides a model platform to understand the effects of processing on the thermal, microstructural, mechanical, and most importantly, the adhesion propertiesin formulated PSAs. PSAs were first solvent casted into films, and then sequentially annealed, first above the melting temperature of poly-L-lactic acid (PLLA) at 170°C, and second at 100°C to cold-crystallize the PLLA. By optimizing the processing history, the LML-based PSAs manifested comparable performance to commercial products in peel and loop tack adhesion, and significantly higher shear resistance. The insights obtained motivates and informs implementation of polyester-based PSAs for practical applications in a wide range of areas.

[0063] An alternative approach would be to use a diblock poly(y-methyl-e-caprolactone)-block- poly(L-lactide) (ML) and blend said diblock copolymers at specific ratios with the LML triblock copolymers in the tackified blends for PSA applications, and explore its effects on the thermal, microstructural, mechanical, and most importantly, the adhesion properties. This approach results in a set of LML / ML blends with tunable LML mass fractions by combining sequential ring-opening transesterification reactions (ROTEP) and a copper-catalyzed alkyne-azido cycloaddition reaction. The LML / ML blends were then mixed with a rosin ester tackifier that selectively swell the poly(y-methyl-e-caprolactone) (PyMCL) rubbery matrix and implemented as PSAs to explore the potential dependence of adhesion and hydrolytically degradation properties on the LML wt% in the blends. The formulated PSAs from tackified LML / ML blends with optimized LML wt% were also prepared by two different methods to demonstrate the potential generalizability of our understandings. To further improve the adhesion properties, the PSAs with optimized formulations were subjected to a two-step annealing process after solvent casting following our previous work. The tackified LML / ML blend-based PSAs manifested tunable and acceptable peel adhesion properties, and decent shear resistance that is comparable to commercial products.

[0064] Tackifiers influence resultant properties of adhesion such as adhesion, cohesion, and viscosity. They can be categorized based on their origin (natural or synthetic), chemical composition (rosin esters, hydrocarbons, etc.), and compatibility with base polymers. Traditionally, they are low molecular weight resins that are added to adhesives to modify their properties, particularly their tackiness and adhesion strength. Tackiness refers to the adhesive's ability to instantly form a bond upon contact, while adhesion strength describes the force required to separate the bonded surfaces. Tackifiers work by increasing the adhesive's viscosity and surface energy. Higher viscosity enables the adhesive to better wet out the substrate, ensuring intimate contact, while increased surface energy improves the ability of the adhesive to interact with the surface molecules of the substrate. This synergistic effect leads to improved adhesion performance, especially in applications where rapid bonding is essential.

[0065] The choice of tackifier depends on the specific adhesive formulation and the intended application. There are various types of tackifiers available, including natural resins like rosin and itsderivatives, as well as synthetic resins like terpene resins, hydrocarbon resins, and acrylic resins. Each type of tackifier offers unique properties, such as varying degrees of tackiness, adhesion strength, and compatibility with different adhesive chemistries. In addition to improving tack and adhesion, tackifiers can also influence other properties of the adhesive, such as its cohesive strength, flexibility, and heat resistance. The right selection of tackifier can help tailor the adhesive's performance to meet the specific requirements of the application.

[0066] Given that this disclosure centers on the need for a hydrolytically degradable pressure sensitive adhesive, the tackifier, likewise, must also be conformant. In some embodiments, the tackifier is selected from Sylvalite 2E 80H, Sylvalite RE 80HP, Eastotac H-130, Foral 85, Piccotac 1115, and combinations thereof. One such tackifier used in exemplary embodiments is Sylvalite RE 80HP produced by Kraton Corporation. It is a light-colored, low-odor rosin ester derived from tall oil rosin. Its chemical composition and properties make it a preferred choice for various adhesive applications, particularly PSAs. Sylvalite RE 80HP provides excellent stability, as it is known for its exceptional stability, ensuring consistent performance and long-term aging properties in adhesive formulations. Additionally, it exhibits excellent compatibility with various polymers and resins commonly used in adhesives, including acrylics, styrene copolymers, and natural and synthetic rubbers. This versatility makes it suitable for a wide range of adhesive formulations. Further, Sylvalite RE 80HP significantly improves the tack and adhesion properties of adhesives, enabling them to quickly and effectively bond to different substrates. With its low odor and light color make it ideal for applications where aesthetics and odor are important considerations, such as in packaging and labeling adhesives. Finally, Sylvalite RE 80HP is derived from renewable resources, making it a more sustainable option compared to tackifiers derived from fossil fuels. The softening point is between 77-83°C, with an acid number less than 10. The Tgis 30°C while the Brookfield viscosity is 1470cps at 125°C, 240cps at 240°C, and 60cps at 170°C. While this is a rosin ester based tackifier, those skilled in the art can contemplate other current tackifiers, and future tackifiers that may allow to meet the ultimate adhesive with desired properties. In the exemplary embodiment, the tackifier is between 20 and 45% of the weight of the adhesive and may frequently just presented as wt% to indicate components are designated by a weight percentage of the whole.

[0067] In exemplary embodiments optional components can be added to the PSAs disclosed herein depending on the desired implementation and function of the PSAs. Optional components can include, but are not limited to: plasticizers, crosslinkers, fillers, stabilizers, wetting agents, dyes and / or pigments, antimicrobial agents, release agents, and flame retardants. Similarly, coatweights of the PSAs discussedherein can range from 1 gram per square meter (gsm) to 100 gsm depending on the function and desired implementation.Release Liners

[0068] In some embodiments, the adhesives herein can be coated onto materials resulting in a construction, a laminate, or a multilayer described herein which can include one or more release liner(s). The liner may have a first side, a second side opposed to the first side, a first edge, and a second edge opposed to the second edge. The liner may be any useful liner which provides necessary support and release properties. The liner may be made of, or from, a variety of materials including, but not limited to, paper or polymer film liners. In some embodiments, the caliper of the paper is sufficient to die cut the resulting laminate or construction. For example, liner calipers can range from about 18 pm to 23 pm for PET liners. In some embodiments, the liner has lay flat properties. In some embodiments, the liner has a machine glaze or finish. In some embodiments, the liner has a silicone hold out layer. The hold out layer provides adhesion between the release coating and the release liner. The silicone holdout layer also prevents the silicone release coating from soaking into the liner.

[0069] In some embodiments, the release liner includes a liner having a release coating. The release coating of the release liner provides a releasable bond with the PSA or other adhesive. The release coating may be any composition which provides a desired releasable bond strength.

[0070] In some embodiments, the release coating is a silicone release coating. The release coating can be prepared by curing silicone polymers in the presence of a control release agent. In some embodiments, the control release agent is a copolymer of a monofunctional silicone unit of the formula R3SiOi / 2and tetrafunctional silicone units SiO4 / 2 wherein R is an alkyl or alkenyl group. In some embodiments, the alkyl or alkenyl groups contain from about 1 to about 12, or from about 1 to about 6 carbon atoms. Non-limiting examples of alkyl and alkenyl groups include methyl, ethyl, propyl, butyl, hexyl, ethenyl, propenyl, butenyl and hexenyl groups.

[0071] The control release agent is typically reacted with a polysiloxane. The polysiloxane may be any polysiloxane which is useful in forming a release coating. Examples of useful polysiloxanes include, but are not limited to, vinyl terminated, hydroxy terminated and epoxy terminated polysiloxanes. In some embodiments, the polysiloxane is a functional polydialkyl siloxane, wherein the alkyl group contains from about 1 to about 6 carbon atoms. The alkyl groups independently include, but are not limited to, methyl,ethyl, propyl, butyl, pentyl, hexyl groups or mixtures thereof. In some embodiments, the alkyl or alkenyl group contains from 1 to about 12, or from 1 to about 6 carbon atoms. The polysiloxane typically has a viscosity average molecular weight of greater than 300,000 centipoise (cps). In some embodiments, the polysiloxane has a viscosity molecular weight from about 300,000 to about 1,000,000 or more. The polysiloxane may be represented by the formula (I):RO((Si(R)2O)x)-Si)-R (I) wherein each R is independently as defined above and x is an integer.

[0072] In some embodiments, the release coating is prepared with a cross linking agent. In some embodiments, the cross linking agent is a reactive polysiloxane, such as a polydialkyl or polyhydroalkyl siloxane. The alkyl groups are the same as those described above.

[0073] The release coating may be applied in a solvent, solvent-less or emulsion form. The release coating may be cured by any known curing process, e.g. thermal, radiation, etc., to form the release coating. The curing may be catalyzed by silicone soluble complexed compounds of Group VIII transition metals, such as platinum.

[0074] Commercially available release agents include, but are not limited to, GE SS-4335, a silicone release agent in unreactive solvent. Commercially available polysiloxanes include, but are not limited to, GE SS-4331, a vinyl terminated polydimethyl siloxane. Commercially available linking agents include, but are not limited to, GE SS-4300C, a polymethyvinyl siloxane. Exemplary catalysts include, but are not limited to, SS-8010 catalyst in toluene. These materials are available commercially from General Electric Company's Silicone Products Division. Similar silicone products are available under the tradename Syl-off from Dow Corning Corporation.

[0075] It will be understood that the present subject matter is not limited to any of the noted release coatings or agents, and instead includes nearly any release coating or agent suitable for the intended end use application. Furthermore, although the present subject matter has been described in association with release liners, it will be appreciated that appropriately configured carrier films and other members could be used instead of release liners.Face Films

[0076] In some embodiments the construction, laminate, or multilayer can include a face film. Suitable face films include, but are not limited to, synthetic papers such as polyolefin type and polystyrene type; various plastic films or sheets such as polyolefin, polyvinyl chloride, polyethylene terephthalate,polystyrene, polyurethane, polymethacrylate and polycarbonate. Additional examples of suitable face films include paper and cardboard. The face film may be, or may include, a multilayer polymeric sheet. The multi-layers may be coextruded, or the multi-layers may be laminated together. In some embodiments, the face film includes both co-extruded multi-layers and laminated multi-layers. In addition, a white opaque film may be formed by adding a white pigment to one or more of the aforementioned synthetic resins and used as the face film. In some embodiments, a foamed film is used as the face film. The foamed film may be formed by a conventional foaming operation. In other embodiments, the face film may be a laminated body formed by combining a plurality of single layered sheets composed of the above listed materials. Examples of such a laminated body may include the combination of cellulose fiber paper with synthetic paper, and a laminated body of combined cellulose fiber paper with a plastic film or sheet. In other suitable embodiments, the face film includes coated and uncoated papers, metalized papers, aluminum foil, laminated paper and paper with a polymeric material extruded onto the surface of the paper. In certain versions, the face film can be coated with a liquid absorbent material. The selected face film may be porous or semi-porous. The face film may exhibit certain visibility characteristics such as opaqueness, color, and / or brightness. The face film may include water or other liquid absorbency properties. The face film may be electrically conductive and / or include electrically conductive coatings or regions. A wide array of commercially available face films can be used such as for example those available under the designation TESLIN sold by PPG.

[0077] The thickness of the face film is optionally determined with reference to application specific criteria. Such criteria may include the desired end use. In some embodiments, the sheet thickness is in a range of from about 10 pm to about 300 pm. In other embodiments, the sheet thickness is in a range of from about 20 pm to about 200 pm. In still other embodiments, the sheet thickness is in a range of from about 30 pm to about 150 pm. Optionally, a primer treatment or a corona discharging treatment or a plasma treatment may be used on the face film to increase a bonding strength between the face film and a dried topcoat composition to be formed on a surface of the face film.

[0078] In certain embodiments described herein, the face film exhibits one or more functions or functional characteristics. For example, the face film may be selected to enable or promote an indication such as a visual indication of a liquid, outgassing such as directing or allowing flow of air or gas across a thickness of the face film, water or liquid retention within the face film, electrical discharge or conductivity of the face film, chemical delivery across a thickness of the face film, passage of sound across a thickness of the face film, and / or combinations of these functions or characteristics.Optional Layers

[0079] The adhesive coated face film and / or laminates described herein can include one or more additional layers or components. Non-limiting examples of such layers include protective layers, tie coat layers, clear layers, color layers, white layers, reflective layers, fluid transfer layers, strength promoting layers, topcoats, print receptive layers, print containing layers, indicia layers, functional layers, and the like.Laminate Properties

[0080] The laminates described herein may have specific and useful properties or functionalities. In some embodiments, the techniques described herein enable formation of laminates in which transfer, propagation, and / or migration of liquid, gas, sound waves, electrical current, and / or other agents or elements can occur and is controlled across or through the laminate in a Z-direction. The reference to "Z- direction" as made herein refers to a direction across a thickness dimension of a laminate or portion thereof, and thus references to "X-direction" and / or "Y-direction" refer to directions perpendicular to the Z-direction and correspond to width and length dimensions of the laminate.

[0081] Non-limiting representative examples of laminates having certain functionalities which are provided by the present subject matter include liquid indicator laminates, outgassing laminates, water absorbent laminates, sound channeling laminates, electrically conductive laminates, and laminates having combinations of these functionalities and / or laminates having combinations of one or more of these functionalities and additional functionalities.

[0082] For example, a liquid indicator laminate can be produced such that the speed of the indicator color change is linked to the facestock selection and porous adhesive properties. A discontinuous structure, such as resulting from pores in the adhesive layer or region(s), can allow, for example, liquid to channel through the discontinuous adhesive from one side of the adhesive to the other side and create a permanent discoloration when a dye or other agent in a functional coating in the laminate is dissolved.

[0083] In some embodiments, a liquid indicator laminate is provided. The speed or rate of the indicator color change is linked to the facestock properties such as for example absorbency of liquid, and porosity of the pattern adhesive in the Z-direction. The indication typically is irreversible and can be measured by color change or by a simple visual comparison.

[0084] The discoloration of a face or region of the laminate can be measured and quantified by optical change, such as by CIE Lab or by a simple visual comparison. The discoloration can be permanentor nonpermanent. The discoloration can also be temporary and revert to an initial state after passage of a period of time. In some embodiments, the period of time is predetermined.

[0085] This phenomenon of transport through discontinuities in an adhesive in the Z-direction can be implemented in other label applications and particularly pressure sensitive adhesive labels, such as for example, labels for outgassing substrates such as by air channeling in the Z-direction, moist substrate labeling such as by liquid channeling in the Z-direction, electrical discharge in the Z-direction, chemical delivery from one layer to another in the Z-direction, and / or sound channeling in the Z-direction. This phenomenon enables passage, transfer, and / or migration of a medium or agent from one side of an adhesive region of a laminate, to another side of the adhesive region. Although medium penetration or transport is noted as being in the Z-direction, it will be understood that the present subject matter is not limited to such and may also include penetration / transport in the X-direction and / or Y-direction.

[0086] In some embodiments, the laminates described herein include a layer or region of a secondary adhesive. The secondary adhesive is typically utilized to adhere the laminate to a substrate of interest. The secondary adhesive may contain one or more adhesives which are the same or different than the adhesive of the patterned or porous adhesive. Description of representative examples of secondary adhesives are provided herein. In such an adhesive configuration, the primary adhesive may be coated onto the facestock, the secondary adhesive may be coated onto the release liner, and the coated adhesive and release liner may be laminated together such that the primary and secondary adhesives are in direct contact with each other. Alternatively, or additionally, both the primary and secondary adhesive may be coated on the facestock or the release liner, then laminated together. It is contemplated that the layering of the primary and secondary adhesive relative to the facestock and the release liner may be either facestock, primary adhesive, secondary adhesive, and release liner or facestock, secondary adhesive, primary adhesive, release liner. Regardless of the order of primary and secondary adhesive, it is contemplated that at least one of the primary and secondary adhesive is patterned, taking into consideration that the other adhesive may be continuous.

[0087] In some embodiments, an array of different arrangements of layers and components may be utilized. In some embodiments using the patterned adhesive, e.g., the layer of discontinuous adhesive, that layer is disposed between a functional facestock and a liner or functional layer. And in the liquid indicator laminates, the patterned adhesive may be disposed between the functional facestock and the layer or region of functional agent that is sensitive to liquid passing through the laminate. And, in the liquid indicator laminates, the layer or region of the functional agent may be disposed between the patterned adhesive and the carrier layer.

[0088] Utilization of the techniques and features described herein enable production of adhesive laminates and / or adhesive coated face films with fluid / air management characteristics, controlled removability, and / or unique thermal and / or electrical conductivity. In addition, use of these techniques and features enable reductions in materials, e.g., adhesives, and thus enable cost savings. However, it will be understood that the present subject matter includes the adhesive coated face films and laminates described herein which are formed by other methods than the methods described herein.Top Coat Formulation and Application

[0089] In exemplary embodiments discussed herein may further include a top coating. The top coating is deposited on the construction, substrate, or laminate by any suitable method. In embodiments, the suitable method includes any suitable coating technology. Embodiments include depositing the coating on the substrate by any suitable liquid deposition method. Without limitation, examples of suitable methods include bath coating, spray coating, slot coating, spin coating, curtain coating, gravure coating, reverse gravure print coating, reverse roll coating, knife over roll (i.e., gap) coating, metering (Meyer) rod coating, air knife coating, or any combinations thereof. Bath coating includes immersion or dip in the aqueous solution. In an embodiment, the coating is deposited by bath in the aqueous solution. In other embodiments, the coating is deposited by spray of the aqueous solution.Exemplary Constructions

[0090] The adhesive discussed herein can be coated onto any surface or substrate to create a construction. When this occurs, the construction involving a layer of the adhesive composition discussed herein and the substrate together has a total thickness between about 5 and 200pm. In some embodiments the thickness is between about 10 and 150pm. In further embodiments the thickness is between about 20 and 100pm. In some embodiments the layer of the adhesive composition has a first thickness and the substrate has a second thickness and a ratio of the first thickness to second thickness is between about 0.1:1 and 1:0.1. In some other embodiments the ratio of first thickness to second thickness is about 1:1. In some embodiments when the substrate is coated onto a face film the face film has a first side and a second side opposite the first side.

[0091] In certain embodiments when the construction is adhered to an article the resultant construction exhibits a peel adhesion, when the layer of the composition is coated onto the face film, of greater than about 0.5 N / cm when tested in accordance with PSTC:101 at a rate of 305mm / min when the construction is applied to stainless steel. Additionally, in other embodiments the construction exhibits apeel adhesion, when the layer of the composition is coated onto the face film, of greater than 2.2 N / cm when tested in accordance with PSTC:101 at a rate of 305mm / min when the construction is applied to stainless steel. In this or another embodiment, the construction exhibits a loop tack adhesion, when the layer of the composition is coated onto the face film, of greater than 0.18 N / cm when tested in accordance with ASTM:D1695 at a rate of 305mm / min when the construction is applied to stainless steel. In some embodiments the construction exhibits a loop tack adhesion, when the layer of the composition is coated onto the face film, of greater than 1.1 N / cm when tested in accordance with ASTM:D1695 at a rate of 305mm / min when the construction is applied to stainless steel. In this or another embodiment, the construction exhibits a shear strength when the layer of the composition is coated onto the face film, of greater than 240 hours when tested in accordance with to PSTC:107 when the construction is applied to stainless steel. In some embodiments the face film is selected from the group consisting of: polyolefins, polyvinyl chloride, polyethylene terephthalate, polystyrene, polyurethane, polymethacrylate, polycarbonate, paper, cardboard, and combinations thereof. In some embodiments the construction can further comprise a liner, wherein the substrate has a first side and a second side opposite the first side, and the liner has a first face and a second face opposite the first face, and the composition is located between the second side of the substrate and the first face of the liner. In some embodiments the liner is selected from the group consisting of: paper, treated paper, polymer film, and treated polymer film. In some embodiments there is a release liner located longitudinally below the composition and longitudinally above the first face of the liner.Methods

[0092] Having discussed various components of the composition and construction, exemplary methods and methodologies of operation will be discussed.

[0093] Specifically, there can be a method comprising, providing a composition comprising a triblock copolymer comprising: poly(L-lactide)-block-poly(y-Methyl-e-caprolactone))-blockpoly(L-lactide) (LML) and a tackifier; coating the composition onto a substrate resulting in a construction; and adhering the substrate to an article. This method can then be modified by dissolving the composition into a solvent prior to coating onto the substrate; removing the solvent after coating onto the substrate resulting in a dried construction; annealing the dried construction at a temperature of 170°C for at least one hour; and quenching the dried construction in less than 5 minutes to a temperature below 25°C. Further, additional steps may occur including annealing a second time the dried construction after the quenching step, at atemperature of 100°C for at least five minutes; and quenching the dried construction a second time, in less than 3 minutes to a temperature below 25°C.

[0094] Additionally, when the construction and the substrate is at the its end of use and is desired to be recycled, the composition adhering the construction to the article will be subject to forces capable of degrading the construction, hydrolytically by exposing the composition to a pH above 10 in an aqueous solution at or above about 45°C. This can be followed by, or occur substantially simultaneously to composting the construction and allowing the easy recyclability of the adhesive and subsequent construction and article in which it is applied.ExamplesSynthesis of poly(L-lactide)-block-poly(y-methyl-E-caprolactone)-block-poly(L-lactide) (LML) and poly(D,L-lactide)-block-poly(y-methyl-E-caprolactone)-block-poly(D, L-lactide) (a LML) triblock copolymers.

[0095] 1,4-benzenedimethanol (BDM) was purchased from Sigma-Aldrich, recrystallized in toluene, and sublimed overnight at 100°C under reduced pressure before storing under nitrogen in the glovebox. y-Methyl-e-caprolactone (yMCL) was purchased from Renewable Solutions, LLC and purified through fractional distillation at 70-100°C under dynamic vacuum around 100 mTorr. L-lactide was provided by NatureWorks, LLC and recrystallized from anhydrous ethyl acetate (3 times) and anhydrous toluene (3 times) under an argon atmosphere and filtered in open air. After recrystallization, the L-lactide was dried for 24 hours at 80°C under vacuum and was stored under a dry nitrogen atmosphere in a glovebox. D,L- lactide was purchased from Sigma-Aldrich and recrystallized from anhydrous ethyl acetate (3 times) and anhydrous toluene (3 times), and filtered in open air. After recrystallization, the D, L-lactide was dried for 72 hours under vacuum at room temperature, and stored under nitrogen atmosphere in a glovebox. Tin (II) 2-ethylhexanoate (Sn(Oct)2) was purchased from Sigma-Aldrich and purified through three fractional distillations under dynamic vacuum, 145-170°C with fractions cooled in a suspension of dry ice and isopropyl alcohol. The products were dried overnight under vacuum, purged with argon, and stored under nitrogen in the glovebox. Deuterium-chloroform (CDCI3) was purchased from Cambridge Isotope Laboratories. Anhydrous toluene was obtained from a JC Meyer solvent drying system and stored over 4A molecular sieves under argon before using. The rosin ester tackifier (Sylvalite 2E 80HP) was provided by Kraton Chemical. All other chemicals were purchased from Sigma-Aldrich and used without further purification unless noted.

[0096] Synthesis was carried out though a PyMCL macroinitiator, ylX / ICL (10 g, 78 mmol), BDM (21.5 mg, 0.155 mmol) and Sn(Oct)2(32 mg, 0.078 mmol) were added into a pressure vessel equipped with a Teflon-coated magnetic stir bar under nitrogen atmosphere in the glove box. The vessel was sealed, taken out of the glove box, and placed in an oil bath preheated to 130°C. After 90 minutes, the vessel was cooled in an ice bath to stop the reaction and dilute with chloroform. The solution was then precipitated into cold methanol (3 times) and hexanes (3 times) before drying in vacuum oven at room temperature for 48 hours.

[0097] Synthesis was carried out though of the LML triblock copolymers, PyMCL (9g, 0.135 mmol) was dissolved in anhydrous toluene (41.6 ml) in the glove box under nitrogen atmosphere for 48 hours to achieve homogenous solution. L-lactide (3 g, 20.8 mmol) and Sn(Oct)2(9.4 mg, 0.0208 mmol) were then added into the solution in a pressure vessel equipped with a Teflon-coated magnetic stir bar. The vessel was sealed, taken out of the glove box, and placed in an oil bath preheated to 130°C. After 90 minutes, the vessel was cooled in an ice bath to stop the reaction and dilute with chloroform. The solution was then precipitated into cold methanol (3 times) and hexanes (3 times) before drying in vacuum oven at room temperature for 48 hours. To synthesize aLML triblock copolymers, similar process was used except replacing L-lactide monomer with D, L-lactide monomer.

[0098] Then, in order to characterize the material as best as possible and determine proper formation of ABA architecture in the LML triblock polymer,1H-NMR and13C-NMR spectra were obtained through using 400 MHz Bruker Avance III HD with SampleXpress. Figure 1 shows the1H-NMR spectra of PyMCL, in CDCI3, with 64 scans. Figure 2 shows the1H-NMR spectra of LML (76.6, 0.27) in CDCI3, 64 scans. As can be seen in this figure, the successful preparation of the LML triblock was also corroborated by the disappearance of signal of the a-hydroxy methylene protons at the ends of PyMCL (6 = 3.7 ppm) and the presence of a new signal of the terminal methine protons at the ends of PLLA blocks (6 = 4.35 ppm). Figure 3 shows the13C-NMR spectra of PyMCL(62.2) (top) and LML(76.6, 0.27) (bottom) with magnified carbonyl region. The sample was run in CDCI3, 512 scans. The absence of transesterification between PyMCL and PLLA blocks was revealed by the presence of two distinctive singlet peaks in the carbonyl region of the LML's spectrum (bottom), indicating the formation of ideal ABA architecture in the LML triblock copolymer. The synthesis produced a triblock copolymer LML (76.6, 0.27) (where 76.6 is the total molar mass of LML, and 0.27 is the PLLA volume fraction ( / PLLA)) with semicrystalline PLLA end-blocks and a small / PLLA as 0.27 which is similar to that of polystyrene in styrenic triblock copolymers for PSA applications.

[0099] Size exclusion chromatography (SEC) was performed with tetrahydrofuran (THF) as mobile phase (25°C, 1 mL / min) on an Agilent Infinity 1260 HPLC system equipped with Waters Styragel HRcolumns, a Wyatt HELEOS-I I multiangle laser light scattering (MALS) detector, and a Wyatt Optilab T-rEX S7 differential refractive index detector. Figure 4 shows the SEC trace of the LML triblock. The tetrahydrofuran (THF) SEC traces as seen in Figure 4 of PyMCL (62.2), PyMCL (67.3), LML (76.6,0.27), and aLML (78.5, 0.22) showed a shift of peak position to shorter elution time compared to that of the PyMCL difunctional macroinitiator while maintaining a monomodal size distribution without a low molar mass shoulder. To resolve the effects of end-block crystallinity on the adhesion properties, the synthesis was repeated using racemic lactide for PyMCL chain extension, producing a poly(D,L-lactide)-block-poly(y- methyl-e-caprolactone)-blockpoly(D,L-lactide) (aLML (78.5, 0.22)) triblock with similar molar mass and composition, but atactic amorphous end blocks. Table 1 below summarizes the molecular characteristics of the as-prepared LML and aLML triblock copolymers. The Mn, PVMCL, Mn, PLA, and Mn, total values were determined using proton nuclear magnetic resonance spectroscopy end-group analysis with CDCI3as solvent. While the / WW,SEC, MALLS was determined using THF-SEC with a multi-angle laser light scattering (MALLS) detector. The Dispersity (D) was determined using THF-SEC with a differential refractive index (Rl) detector, and the / pLLA, or the total PLLA volume fraction, was calculated from block Mnvalues using PyMCL = 1.037 g / cm3and pPLLA =1.25 g / cm3.Table 1Synthesis of alkyne-terminated poly(y-methyl-E-caprolactone) (Alkyne-PyMCL), alkyne-terminated poly(L-lactide)-block-poly(y-methyl-E-caprolactone) (Alkyne-ML), and linked poly(L-lactide)-block- poly(y-methyl-E-caprolactone) (Linked-ML)

[0100] To synthesize alkyne-PyMCL macroinitiator, yMCL (10 g, 78 mmol), 3-butyn-l-ol (21.8 mg, 0.312 mmol) and Sn(Oct)2(32 mg, 0.078 mmol) were added into a pressure vessel equipped with a Teflon- coated magnetic stir bar under nitrogen atmosphere in the glove box. The vessel was sealed, taken out of the glove box, and placed in an oil bath preheated to 130 °C. After 90 minutes, the vessel was cooled in an ice bath to stop the reaction and dilute with chloroform. The solution was then precipitated into coldmethanol (3 times) and hexanes (3 times) before drying in vacuum oven at room temperature for 48 hours.

[0101] To synthesize alkyne-ML triblock copolymers, alkyne-PyMCL (9g, 0.271 mmol) was dissolved in anhydrous toluene (41.6 ml) in the glove box under nitrogen atmosphere for 48 hours to achieve homogenous solution. L-lactide (3 g, 20.8 mmol) and Sn(Oct)2(9.4 mg, 0.0208 mmol) were then added into the solution in a pressure vessel equipped with a Teflon-coated magnetic stir bar. The vessel was sealed, taken out of the glove box, and placed in an oil bath preheated to 130 °C. After 90 minutes, the vessel was cooled in an ice bath to stop the reaction and dilute with chloroform. The solution was then precipitated into cold methanol (3 times) and hexanes (3 times) before drying in vacuum oven at room temperature for 48 hours.

[0102] The successful synthesis produced linked-ML or LML triblock architecture with identical arm length and fPLLA as ML diblock copolymers, which was characterized by1H NMR (Figure 5) and SEC (Figure 6). All1H NMR traces show significantly reduced intensity of alkyne end group signal (1.95 ppm) and emergence of new peaks that correlated to methylene groups of p-xylene at 5.5 ppm and that connected to alkene of triazole rings at 2.8 ppm. The similar peak integration areas of these two distinctive methylene resonances indicate azido ends on the linker both reacted with alkyne groups on ML(38.8, 0.26), suggesting the successful formation linked-ML. It is important to note that the LML wt% in the as-formed blends can be readily tuned by the stoichiometric ratio between alkyne group on ML(38.8, 0.26) and azido group on the bifunctional linker. The LML wt% in the blends were calculated by the reaction conversion from the comparison of peak integration areas between hydroxyl termination resonance (2.65 ppm) and methylene resonance of p-xylene (5.5 ppm), while a full conversion of ML to LML would lead to a ratio of 1 to 2 and a 100 wt% LML in the blend. For instance, a 50% conversion of the cycloaddition reaction would yield a 1 to 1 ratio of these two peaks (third trace from the bottom in Figure 5). Since the as-formed LMLs would have roughly twice of the molar mass of pristine alkyne-ML(38.8, 0.26), the 50% conversion of alkyne-ML(38.8, 0.26) would produce a LML / ML blend with 50 wt% LML. Three LML / ML blends were prepared with 25 wt% (second trace from the bottom in Figure 5, denoted 25 wt% LML), 50 wt% (third trace from the bottom in Figure 5, denoted 50 wt% LML), and 75 wt% (top trace in Figure 5, denoted 75 wt% LML) LML, respectively. However, previous studies showed that the second ROTEP of L-lactide would also produce PLLA homopolymer together with the formation of block copolymers,30, 37which may inevitably create errors in accurately determining, and very likely, underestimating the reaction conversion and LML mass fraction in the blends byXH NMR.

[0103] Table 2 below shows the molecular characteristics of the as-prepared alkyne-ML block copolymer, calculated in a manner consistent with Table 1.Table 2Synthesis of a,a'-diazido-p-xylene bifunctional linker

[0104] The compound a,a'-dibromo-p-xylene (2.64 g, 10 mmol) was dissolved in 20 ml of dimethylformamide (DMF) before the addition of sodium azide (1.3 g, 20 mmol). The solution was stirred for 24 hours at room temperature. The product was extracted by diethyl ether, washed with brine (2 times), and dried with sodium sulfate. The solvent was then evaporated by rotary evaporation, leaving yellowish solid product. The product was dried in vacuum oven at room for 12 hours before storing in fridge. The purified a,a'-diazido-p-xylene, light yellowish powder, was characterized via1H NMR (Figure 7) and stored in fridge before further use.Synthesis of LML / ML blends with different LML mass fractions by copper-catalyzed alkyne-azido cycloaddition reaction

[0105] To exclude the potential interferences from distinct compositions and variation of arm length of LML and ML in the blends, we proposed a convenient strategy to prepare end group functionalized ML via two-step ROTEPs, followed by a copper-catalyzed alkyne-azido cycloaddition reaction to link ML, and form LML / ML blends with a bifunctional linker. Afterwards, the alkyne-terminated PyMCL with hydroxyl end was used as macroinitiator for the second Sn(Oct)2-catalyzed ROTEP of L-lactide at 130 °C for 90 mins in toluene. The as-prepared alkyne-ML diblock copolymers were purified and characterized by1H nuclear magnetic resonance (NMR) spectroscopy (Figures 8 and 9, respectively) and size exclusion chromatography (SEC) (Figure 10). The SEC trace of alkyne-ML shows a clear shift in the elution time compared to that of its parent PyMCL, while the1H NMR spectra also indicates a shift of methane terminal resonance from 3.7 ppm of PyMCL to 4.4 ppm of PLLA, suggesting the successful preparation of ML diblock copolymers. The alkyne termination of ML diblock copolymers is also validated by the presence of a peak around 1.95 ppm in the1H NMR spectra. The alkyne-terminated ML diblock copolymer, denoted alkyne-ML(38.8, 0.26), has a total molar mass of 38.8 kg / mol and a small PLLA volume fraction (fpi_i_A) as 0.26 which is similar to that of PLLA or PS hard blocks in block copolymers for PSA applications.

[0106] Alkyne-ML diblock copolymers were dissolved in THF with a concentration of 0.1 g / ml under stirring. a,a'-diazido-p-xylene, copper (I) bromide (CuBr) and N,N,N,N,N-pentamethyldiethylenetriamine (PMDETA) were then added into the THF solution in a round-bottom flask. The round-bottom flask were then purged with argon and covered with alumina foil to avoid light exposure.

[0107] The molar ratio of alkyne termination on alkyne-ML diblock copolymer to azido group on a,a'- diazido-p-xylene, CuBr, and PMDETA is 1: 0.4 :5 : 10 for LML / ML blends with 25 wt% of LML, 1: 0.75: 5: 10 for LML / ML blends with 50 wt% of LML, and 1: 1.1: 5: 10 for LML / ML blends with 75 wt% of LML.

[0108] After continuous stirring for 24 hours, the solution was concentrated to half volume by rotary evaporation, followed by precipitation in cold methanol. The solid product was dissolved in chloroform before passing through a neutral alumina column to remove CuBr and PMDATE. The solution was then precipitated into cold methanol again to obtain white, solid product of LML / ML blends.

[0109] In addition, the successful preparation of a series of LML / ML blends was also reflected by the continuous shift of peak elution time in the SEC measurement (Figure 6) and change of molar mass detected (Table 3, below). The high dispersity of starting alkyne-ML(38.8, 0.26) and as-formed blends lead to the observation of monomodal shape on respective trace of the blend. While the molar masses of 25 wt% LML and 50 wt% LML blends follow the expectations, the 75 wt% LML blend seems to yield a molar mass (81.6 kg / mol) even slightly higher than the theoretical molar mass of LML from fully converted alkyne-ML(i.e., 77.6 kg / mol). In literature, the azido functionalized polyacrylates would cross-link to form a network via nitrene insertion into C-H backbone under UV light irradiation. To explore the potential effect of this nitrene insertion side reaction, a control sample of ML(37.5, 0.22) (Table 4, below, where 37.5 is the total molar mass of ML and 0.22 is RLLA) with similar molar mass and composition was prepared via two-step ROTEPs without alkyne-functionalized initiator, but benzyl alcohol as initiator, followed by the copper-catalyzed alkyne-azido cycloaddition reaction with a, a -diazido-p-xylene linker under same conditions. As shown in Figure 11, the SEC traces of the ML(37.5, 0.22) shows almost identical peak shapes and elution time, indicating the nitrene insertion reaction is very unlikely happened under these conditions. The slightly higher molar mass of 75 wt% LML blend may be a combined result from underestimated amount of LML, errors in SEC measurement, and high dispersity of starting alkyne- ML(38.8, 0.26). Note that the / WW,SEC, MALLS was determined via THG-SEC using a multi-angle laser light scattering (MALLS) detector, while the D was measured using THF-SEC with differential refractive index (Rl) detector. While the values in Table 4 were measured consistent with those in Tables 1 and 2, above.Table 3Table 4

[0110] On the other hand, in the1H NMR trace of 25 wt% LML blend, the peak intensity of alkyne termination of residue ML seems to be much lower than the expectations from end-group analysis as mentioned above. To verify if alkyne-ML(38.8, 0.26) with active alkyne terminations remains in the blend, a small portion of 25 wt% LML blend was reacted with excess ct,a!'-diazido-p-xylene bifunctional linker (molar ratio of azido to residual alkyne = 2:1) again under same conditions of first copper-catalyzed alkyneazido cycloaddition reaction. Intrigui ngly, the THF SEC results (Figure 12 and Table 5) showed the molar mass of the 25 wt% LML blend can be further increased to 77.8 kg / mol, which is close to the theoretical maximum value of pure LML blend (77.6 kg / mol). As a consequence, this results suggested the alkyne terminations remained active in the blends with high ML residue and the excess azido linker would not lead to unfavorable nitrene insertion side reaction. Table 5 was measured in an identical manner to Table 3 above.Table 5Synthesis of LML / ML blends with 50 wt% of LML via sequential ring-opening transesterification polymerizations with the presence of both benzyl alcohol and BDM

[0111] PyMCL macroinitiator, ylX / ICL (10 g, 78 mmol), benzyl alcohol (14.5 mg, 0.208 mmol), BDM (14.4 mg, 0.104 mmol) and Sn(Oct)2(32 mg, 0.078 mmol) were added into a pressure vessel equipped with a Teflon-coated magnetic stir bar under nitrogen atmosphere in the glove box. The vessel was sealed, taken out of the glove box, and placed in an oil bath preheated to 130 °C. After 90 minutes, the vessel was cooled in an ice bath to stop the reaction and dilute with chloroform. The solution was then precipitated into cold methanol (3 times) and hexanes (3 times) before drying in vacuum oven at room temperature for 48 hours.

[0112] To make the LML / ML blends, PyMCL (9g) was dissolved in anhydrous toluene (41.6 ml) in the glove box under nitrogen atmosphere for 48 hours to achieve homogenous solution. L-lactide (3 g, 20.8 mmol) and Sn(Oct)2(9.4 mg, 0.0208 mmol) were then added into the solution in a pressure vessel equipped with a Teflon-coated magnetic stir bar. The vessel was sealed, taken out of the glove box, and placed in an oil bath preheated to 130 °C. After 90 minutes, the vessel was cooled in an ice bath to stop the reaction and dilute with chloroform. The solution was then precipitated into cold methanol (3 times) and hexanes (3 times) before drying in vacuum oven at room temperature for 48 hours. To exclude the potential interferences from distinct compositions and variation of arm length of LML and ML in the blends, end group functionalized ML via two-step ROTEPs were prepared, followed by a copper-catalyzed alkyne-azido cycloaddition reaction to link MLPSA Preparations

[0113] PSAs were prepared by blending LMLs with a renewable rosin ester tackifier (Sylvalite RE 80HP) in chloroform for convenience. The mass fractions of tackifier in the blends were varied from 20 wt% (~20 parts per hundred, PHR, of adhesive) to 33 wt% (33 PHR) and 43 wt% (43 PHR) to tailor the properties of the as-prepared PSAs. Afterwards, the PSAs were prepared by solvent casting via a wire wound rod on polyethylene terephthalate) (PET) film (40pm, Chemlnstruments), followed by drying under nitrogen flow for 48h at room temperature, resulting in PSA film thicknesses around 80pm. The PSA formulations were first annealed on the PET backing at 170°C for 60 min under nitrogen atmosphere,rapidly quenched (approximately 35°C / min) to room temperature, and then annealed at 100°C for 5 min under a nitrogen atmosphere before a final quench to room temperature at a rate of approximately 35°C / min. As seen in Figures 13 and 14, there was no change in the1H-NMR spectrum or the SEC trace of LML (76.6, 0.27) after 170°C and 100°C annealing, indicating no significant degradation took place during annealing. Specifically Figure 13 shows a series of1H-NMR spectra of LML (76.6, 0.27) after solvent casting (top), solvent casting and first annealing at 170°C (middle), and solvent casting, first annealing at 170°C as well as second annealing 100°C (bottom), suggesting no change in molecular characteristic after distinctive processing history using CDCI3, 400 MHz, 64 scans. While Figure 14 shows the THF SEC traces of LML(76.6, 0.27) after solvent casting (bottom); solvent casting, first annealing at 170°C for 60 minutes and then rapid cooling to room temperature (middle); solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes and rapid cooling to room temperature (top). (Vertically shifted for clarity).

[0114] LML / ML blends with 20 wt% tackifier were dissolved in chloroform overnight to yield a 20 wt% homogeneous solution, followed by casting onto a poly(ethylene terephthalate) (PET) substrate (40 pm, Chemlnstruments) using a wire wound rod. The PSAs were then dried under continuous nitrogen flow at room temperature for 48 hours. The thickness of the dried film was roughly 80 pm.

[0115] For the two-step annealing, the PSAs were first put into an oven preheated to 170 °C for 1 hour under nitrogen atmosphere, followed by rapid quenching (approximately 35 °C / min) to room temperature on a cold metal substrate. Subsequently, the PSAs were put into an oven preheated to 100 °C for 5 minutes under nitrogen atmosphere, followed by rapid quenching (approximately 35 °C / min) to room temperature on a cold metal substrate.

[0116] Small-angle X-ray scattering (SAXS) was acquired from 15-minute exposures in the Characterization Facility, University of Minnesota, using a Xenocs instrument (Ganesha). Thin film samples were prepared from specific processing history before mounting up on Kapton tape and exposure at room temperature. As shown in the small angle X-ray scattering (SAXS) patterns in Figure 15, the pristine LML (76.6, 0.27) and blends of LML (76.6, 0.27) with tackifier showed broad principal correlation peaks and no higher-order peaks after solvent casting, indicating a microphase-separated morphology but without long- range order. The rapid evaporation of chloroform during the solvent casting and drying process of PSAs likely trapped the LML and blends in this likely non-equilibrium state. The principle domain spacing D = 2n / q* is 39.8 nm for LML (76.6, 0.27) at room temperature, where the q* is the scattering vector at the primary peak, the addition of tackifier slightly shifted the q* to lower values and increased domain spacing of the blends to 45.5 nm (20 wt% tackifier), 48.0 nm (33 wt% tackifier), and 48.7 nm (43 wt% tackifier).Given the absence of additional peaks in the blends, these results suggested the tackifier is compatible with LML (76.6, 0.27) and likely swells the rubbery matrix.

[0117] The processing effects on the microstructure of the blend of LML (76.6, 0.27) with 33 wt% tackifier were then probed by SAXS, which can be seen in Figure 16. In this figure, the SAXS patterns of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting can be seen on the bottom; solvent casting, then first annealing at 170°C for 60 minutes and then rapid cooling to room temperature is in the middle; while solvent casting, then first annealing at 170°C for 60 minutes followed by a second annealing at 100°C for 5 minutes and rapid cooling to room temperature can be seen at the top (vertically shifted for clarity).

[0118] Similar to above, SAXS patterns (Figure 17) of pristine alkyne-ML(38.8, 0.26) and three LML / ML blends showed broad principal correlation peaks and no higher-order peaks after solvent casting with chloroform. The rapid chloroform evaporation during the solvent casting and drying process likely trapped the blends in this likely non-equilibrium state resulting in microphased-separated morphology without long-range order. The similar microstructures observed in the alkyne-ML(38.8, 0.26) and three LML / ML blends highlighted that the introduction of molecular linkage and bridging PyMCL chains did not affect the microstructure during solvent casting, which is similar to the case of poly(cyclohexylethylene)- block-poly(ethylene) multi-block polymer blends. The principle domain spacing D = 2n / q* is 22.8 nm for alkyne-ML(38.8, 0.26) at room temperature, where the q* is the scattering vector at the primary peak. Intriguingly, under same processing conditions, the q* shifted to lower values and domain spacing increased to 26.7 nm of 25 wt% LML blends, 31.9 nm of 50 wt% LML blends, and 38.8 nm of 75 wt% LML blends. These results also corroborate the linking of alkyne-terminated ML diblock copolymers produced LML triblock architecture in the blends with higher molar mass and longer chain length, potentially contributed to more bridging PyMCL chains that connect to two PLLA hard domains in the rubber PyMCL matrix.

[0119] The thermal properties of the blends were investigated by differential scanning calorimetry (DSC) measurements were determined operating the instrument at a heating of 10°C / min. Thermogravimetric analysis (TGA) was performed on a TA Instruments Q500 under nitrogen atmosphere. Thermal properties were investigated via differential scanning calorimetry measurements under nitrogen flow with a TA Instruments Discovery Series differential scanning calorimeter and a refrigerated cooling system.

[0120] As shown in Figure 18 and summarized in Table 6 below, the first annealing of the blend at 170°C melted the PLLA crystals (Tm,PLLA (melting temperature of semicrystalline PLLA)) centered around162°C (and provided more mobility to the system. Figure 18 shows DSC traces of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting (first heating, 10°C / min; vertically shifted for clarity). As a consequence, enhanced primary peak intensity and reduced domain spacing from 48.0 nm to 40.7 nm as indicated by the primary peak position q* were observed (Figure 16, middle trace). In addition, a shoulder at roughly V3 q* and a broad secondary peak around V7 q* developed (Figure 16, middle trace), suggesting more complete microphase separation with moderately long-range domain ordering. However, due to the broadness of higher-order peaks (which resemble spherical form factor scattering), it is difficult to definitively assign an order morphology. These results are corroborated by previous reports in which LMLs with similar volume fraction of PLLA exhibited similar patterns after melt processing at 180°C and were concluded to adopt spherical or cylindrical PLLA domains with poor long- range order in a PyMCL matrix. The second annealing at 100°C, which induced cold crystallization in PLLA domains (Discussed later with respect to Figure 24 and Table 10), did not distinctively affect (e.g., breakout crystallization) the morphology (top trace in Figure 8), possibly owing to the short annealing time.

[0121] Table 6 summaries the thermal properties of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting. Figure 9 shows the first heating trace of LML (76.6, 0.27) (bottom trace) after solvent casting showed a Tg,pvMcL at -61°C, a Tg, PLLA at 54°C, a cold crystallization temperature of semicrystalline PLLA at 98°C, and a Tm,PLLA (melting temperature of semicrystalline PLLA) centered around 162°C.Table 6

[0122] Both the Tg, PVMCL and Tg, PLLA were determined during the DSC measurement while the Tm,PLLA was determined as the peak of melting endotherm during DSC measurement. The Degree of Crystallinity was determined using Equation (I) below:where Hmis the enthalpy of melting taken as the area under the melting endotherm during the first heat at 10°C / min,= 93 J / g, and wPLLAis the weight fraction of the PLLA. The clear presence of Tg'sfor both blocks, combined with the aforementioned SAXS measurements, confirm phase separation between PyMCL and PLLA, similar to previous reports on LML triblocks. As mentioned above, the rapid evaporation of chloroform may trap the PSA in a non-equilibrium state, which can also contribute to low crystallinity (i.e., 0.1 for LML (76.6, 0.27) in Table 6) in the PLLA domains.

[0123] On the other hand, neat tackifier has a Tgat 34°C. In the blends, Tg,PLA only slightly changed from 54°C to 47°C (20 wt% tackifier) and 51°C (33 wt% tackifier), and Tg,p LAwas not detectable in the blend of 43 wt% tackifier (likely owing to the low volume fraction of PLLA in the blend), indicating no or limited miscibility of tackifier with PLLA, which is consistent with the literature. The addition of increasing tackifier weight fraction monotonically increased the Tg,PvMcL from -61°C to -54°C (20 wt% tackifier), -46°C (33 wt% tackifier), -41°C (43 wt% tackifier), suggesting tackifier is preferentially localized in the PyMCL rubbery matrix.

[0124] However, in order to calculate the glass transition temperature of the mixed domain, the Flory-Fox equation must be used. This is shown below in Equation II below:where Tg, mixed domain is the glass transition temperature of the mixed domain, Tgiiis the glass temperature of component , andwiis the weight fraction of component i. Given immiscible PyMCL and PLA domains, the expected Tg,miXed domain is calculated assuming all tackifier preferentially mixes with PyMCL domain, and by Tg, pVMCLand Tg, tackifier with different weight fraction.

[0125] Using this equation, the calculated Tg,PVMCL of the blends (i.e., -49°C (20 wt% tackifier), -38°C (33 wt% tackifier), -30°C (43 wt% tackifier)) are higher than the observed values, indicating potentially imperfect mixing among tackifier and PyMCL particularly at high tackifier loading. On the other hand, it is important to note that a small Tgaround 35°C presented in the trace of blend with 43 wt% tackifier, which is close to the Tgof neat tackifier, indicating that the tackifier may be starting to separate from the rubbery matrix at such high loading. However, the as-prepared PSA from the blend with 43 wt% tackifier remained transparent without observable macroscopic phase separation, possibly owing to the trace amount of precipitated tackifier as reflected by the small amplitude of heat capacity increase at this apparent glass transition in the blend.

[0126] The thermal properties were investigated by DSC (Figure 19) and concluded in Table 7. After solvent casting, the first heating traces of alkyne-ML(38.8, 0.26) and LML / ML blends all showed a Tg,PyMCL around -60 °C, a Tg, PLLA around 54-59 °C, a Tm,PLLA (melting temperature of semicrystalline PLLA) centered around 160 °C, indicating the alkyne-ML(38.8, 0.26) and LML / ML blends share similar thermal properties. Together with the aforementioned SAXS measurements, the clear presence of Tg's for both blocks confirm the phase separation between PyMCL and PLLA, which is also observed in previous publications on LML triblocks.27, 30-31 The crystallinities of PLLA remained low (i.e., around 0.1 in Table 7) and similar in all blends without clear trend, which may be a result of rapid evaporation of chloroform and formation of non-equilibrium microstructure after processing. The appearance of additional shoulder in the melting endotherms of alkyne-ML(38.8, 0.26) and 25 wt% LML traces may be attributed to the formation of smaller PLLA crystals or less-perfect a' -form of PLLA crystals, which normally have a lower melting temperature than the more stable a-form PLLA crystals.41 On the other hand, the alkyne- ML(38.8, 0.26) and 25 wt% LML blend could cold crystallize around 95 °C (peak temperature of cold crystallization exothermal). Differently, the 50 wt% LML blend shows a similar peak temperature of cold crystallization exothermal at 94 °C, but a broad cold crystallization peak, while 75 wt% LML blends only cold crystalized at 110 °C with a broad peak shape and smaller amplitude. In the case of poly(ethylene glycol)-block-poly(L-lactide) block copolymers (PEG-b-PLLA) with distinctive architectures, the increased arm number of PEG-b-PLLA with same molar masses of PLLA and PEG would yield reduced PLLA crystallinities, which is attributed to the reduced mobility of the block copolymers of more complex architecture.42 The reduced cold crystallization kinetics have also been reported in poly(L-lactide)-block- poly(ethylene-co-ethylethylene) polymers with multi-block architecture and restricted chain mobility of bridges and loops.43 In this context, the increase of cold crystallization temperature and broadening of cold crystallization peaks may also reflect the presence of more LML triblocks with reduced mobility in the 50 wt% LML and 75 wt% LML blends.Table 7

[0127] Atomic force microscopy (AFM) was conducted on thin film samples on a Bruker Nanoscope V Multimode 8 open-loop system in peak force mode. Water contact angle measurements were made by mounting samples on a glass slide and analyzing them with a microscopic contact angle meter (Kyowa Interface Science Co). The images were captured by a horizontal camera with a high magnification lens and processed using FAMAS image processing software. Enhanced microphase separation and absence of long-range order were also observed by AFM in Figure 20 under adhesion contrast in the peak force mode. The dark spheres situated in a lighter background suggested the presence of a rubbery matrix (i.e., PyMCL mixed with tackifier) with stronger tip adhesion and isolated hard domains (i.e., semicrystalline PLLA) with weaker tip adhesion. Figure 20 shows AFM (adhesion contrast) and water contact angle measurement of blend of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting ((a) and (c)), and solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature ((b) and (d )). Compared to that of the solvent-casted PSA, the PSA after two-step annealing exhibited more spherical domains randomly distributed in the matrix, corroborating the results discussed above from SAXS measurements. Even though the annealing process enhanced the microphase separation, it is important to note that the PSA showed similar water contact angles (See Figure 20 at (c) and (d) ) reflecting similar surface energies.

[0128] After two-step annealing, the microstructures of PSAs with different weight ratios of tackifier were revealed by SAXS and shown in Figure 21. These SAXS patterns of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature (vertically shifted for clarity). Compared to solvent casting (Figure 13), the two-step annealing produced enhanced microphase separation as expected, which is reflected by the increased primary peak intensities and presence of broad higher-order peaks. Similar to Figure 13, adding more tackifier swelled the rubbery matrix and increased the domain spacing from 31.9 nm of pristine LML (76.6, 0.27) to 33.0 nm (20 wt% tackifier), 40.7 nm (33 wt% tackifier), and 42.2 nm (43 wt% tackifier). Moreover, the intensities of high-order peaks are proportional to the weight fraction of tackifier. The addition of more tackifier may enhance the mobility of LML in the blends, allowing the blends to reach more strongly segregated microstructure during annealing. Moreover, the presence of tackifier may change the interaction parameter for the tackifier swollen matrix with the minority PLLA domains, which may refine the domain structure by modulating the effective segregation strength.

[0129] The thermal properties of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting and first annealing at 170°C for 60 minutes are shown in Table 8 below.Table 8

[0130] Similar to Table 6 above, Both the T&PVMCL and T&PLLA were determined during the DSC measurement while the Tm,PLiA was determined as the peak of melting endotherm during DSC measurement. The Degree of Crystallinity was determined using equation (I) where Hmis the enthalpy of melting taken as the area under the melting endotherm during the first heat at 10°C / min,= 93J / g, and wPLLAis the weight fraction of the PLLA.

[0131] After first annealing at 170°C under nitrogen atmosphere and rapid quenching to room temperature, the first heating DSC traces of LML (76.6, 0.27) and blends with 20 wt% and 33 wt% tackifier showed no PLLA melting peak in Figure 22, signifying amorphous PLLA domains as would be expected from annealing above Tm. On the other hand, after 170°C annealing, the Tg's of the respective polyester blocks were unchanged relative to that of the solvent-casted films. From these results, we conclude that the 170°C annealing did not promote tackifier mixing with the other components in the blends, but led to enhanced microphase separation and mostly amorphous PLLA domains.

[0132] Figure 22 shows the DSC traces of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature, (first heating, 10°C / min) (Vertically shifted for clarity). A small melting peak was observed at 158°C in the blend with 43 wt% tackifier and a small Tgaround 35°C of precipitated tackifier still remained in the trace, indicating the high-temperature annealing did not further promote the mixing of high-loading tackifier with the rubbery PyMCL matrix. Therefore, the incompatible and precipitated tackifier may be serving serve as nucleating agent to induce rapid PLLA crystallization even after prolonged annealing at 170°C and rapid quenching to room temperature.

[0133] Annealing semicrystalline PLLA around 100°C triggers the crystallization of PLLA, which in PSAs strengthens the physical crosslinks in the PLLA domains better anchoring the rubbery matrix providing enhanced creep resistance. Therefore, a second annealing at 100°C was conducted under nitrogen atmosphere for 5 min, followed by rapid quenching to room temperature. The DSC traces are shown in Figure 23. These traces are of LML (76.6, 0.27) (bottom), tackifier (top, denoted Sylvalite 2E 80HP), and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature (first heating, 10°C / min; all traces are vertically shifted for clarity). Results are summarized in Table 9 below.Table 9

[0134] Similar to Table 8 and 9 above, Both the Tg,PvMcL and Tg,p LAwere determined during the DSC measurement while the Tm,PLi was determined as the peak of melting endotherm during DSC measurement. The Degree of Crystallinity was determined using equation (I) where Hmis the enthalpy of melting taken as the area under the melting endotherm during the first heat at 10°C / min,= 93J / g, and wPLLAis the weight fraction of the PLLA.

[0135] As shown in Figure 23, the second annealing did not significantly change the Tg,PVMCL and Tg, PLLA in LML(76.6, 0.27) and the blends (Table 8 compared to Table 9). Small melting endotherms centering at 110°C were observed in the traces of neat LML(76.6, 0.27) and the blend with 20 wt% tackifier, which may be attributed to the formation of less-perfect a' -form of PLLA crystals, which normally have a lower melting temperature than the more stable a-form, formed during 100°C annealing. The crystallinities of PLLA in the blends remained low (i.e., around 0.1) after annealing at 100°C for 5 minutes (Table 9).

[0136] With an example of the blend with 33 wt% tackifier shown in Figure 24 and Table 10 below, the crystallinity of PLLA was found to be proportional to the annealing time at 100°C due to the crystallization process. DSC traces of a blend of LML(76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 0-30 minutes, and rapid cooling to room temperature (first heating, 10°C / min, vertically shifted for clarity) is specifically shown in Figure 24.Table 10

[0137] Similarly with the above tables, the Degree of Crystallinity was determined using equation (I) where Hmis the enthalpy of melting taken as the area under the melting endotherm during the first heat at 10°C / min,= 93 J / g, and wPLLAis the weight fraction of the PLLA.Linear Viscoelastic Properties

[0138] Linear viscoelastic properties were probed via small amplitude oscillatory shear (SAGS) experiments with a TA ARES G2 rheometer and 8 mm parallel-plate fixture. Samples were processed after specific history before molding on the rheometer at 80°C. All experiments were carried out in the linear viscoelastic region determined by dynamic strain sweep at -20°C and a frequency of 1 rad / s. Frequency sweeps were performed at 1 % strain and temperatures from -20 to 80°C.

[0139] For an effective PSA, the Dahlquist criterion was developed to highlight that the storage modulus (G') should be lowerthan 0.3 MPa at a frequency of 1 rad / s to endow effective substrate wetting, while tan(6) (i.e., G" / G', where G" is the loss modulus) should be 0.1-1 to allow for energy dissipation during debonding while maintaining sufficient cohesive strength. These can be seen in Figures 25-27. The results were shifted to generate a master curve with a reference temperature at 20°C. The blends with 43 wt% tackifier failed to generate reproducible data possibly due to some macrophase separation.

[0140] Specifically Figure 25, at (a) shows Master curves for the storage modulus (G') and loss modulus (G") of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at170°C. While Figure 26 shows Master curves for the storage modulus (G') and loss modulus (G") of (a) LML(76.6, 0.27) and (b) blend of LML(76.6, 0.27) with 20 wt% tackifer after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature. The Dahlquist criterion (G' = 0.3 MPa at 1Hz) is marked by dashed lines. Figure 27 are the master curves for the storage modulus (G') and loss modulus (G") of (a) LML (76.6, 0.27) and blends of LML (76.6, 0.27) with (b) 20 wt%, and (c) 33 wt% tackifier after solvent casting. The Dahlquist criterion (G' < 0.3 MPa at 1 rad / s) is marked by dashed lines.

[0141] PyMCL has a reported entanglement molar mass (Me) of 2.9 kg / mol and thus LML (76.6, 0.27) should possess a well-entangled rubbery matrix. Following methods from previous reports, the Meof LML (76.6, 0.27) was calculated to be 2.7 kg / mol after solvent casting and 3.1 kg / mol after two-step high temperature annealing (See Figure 26 at (a) and Figure 27 at (a)). However, the G' at 1 rad / s of PSAs from both processing histories are much higher (i.e., 1.76 MPa after solvent casting and 1.51 MPa after two- step annealing) than the 0.3 MPa Dahlquist criterion, thereby leading to more elastomeric behavior and poor adhesion properties due to ineffective substrate wetting.

[0142] Increasing the weight fraction of tackifier in the blends significantly reduced the G' at 1 rad / s (i.e., to 0.53 MPa in the blend with 20 wt% tackifier and 0.21 MPa in the blend with 33 wt% tackifier post two-step annealing), indicating effective dilution of chain entanglements in the rubbery PyMCL. Moreover, a drop of modulus present at high frequencies in the blends, likely due to the increased Tgof rubbery matrix, followed by another drop of modulus at low frequencies at a similar frequency to that of pristine LML (76.6, 0.27). Compared to solvent casting samples (Figure 27), the two-step annealing process leads to similar shapes of master curves (Figure 25 at (a) and Figure 26) of both LML (76.6, 0.27) and the blends, but a slightly lower plateau modulus and higher tan(6), possibly owing to more pronounced microphase separation as revealed by the SAXS. For instance, at 1 rad / s, the blend of 33 wt% tackifier resulted in a drop of G' from 0.47 MPa to 0.21 MPa and an increased tan(6) from 0.13 to 0.32.

[0143] Viscoelastic windows analysis was previously developed to guide the design of PSAs based on its G' and G" at the frequencies of bonding (0.01 rad / s) and debonding (100 rad / s). By plotting the resulting four coordinates on a cross-plot of G' as the ordinate and G" as the abscissa in a range of 103- 106 Pa (Figure 25 at (b)), the potential application of a particular PSA can be identified based on its property-determined quadrant. As shown in the Figure 25 at (b), after two-step annealing, the PSA from pristine LML (76.6, 0.27) partially lies in the Quadrant 2 of high G' and G", indicating potential application as a high shear strength PSA. Increasing tackifier loading in the blends decreases both G' and G" of the corresponding PSAs in Quadrant 2, suggesting their potential application as high shear strength PSA withimproved substrate wetting abilities. Without the two-step annealing process, the solvent casting PSAs exhibited high G' that partially displaced them from Quadrant 2 even with the addition of tackifier (Figure 28), highlighting the importance of imposing desired processing history to create microstructures with optimized mechanical and adhesion properties rather than solely solvent casting.

[0144] The linear viscoelastic properties of the Alkyne-ML and 75 wt% blend LML were investigated using SAGS with frequency sweeps between -20 to 80 °C (Figure 29 and Figure 30). Master curves were generated by horizontally shifted the results with a reference temperature at 20 °C. As noted above, effective PSAs should readily wet the adherend as viscous liquid during a one-second bonding time, which requires the storage modulus (G') to be less than 0.3 MPa at 1 rad / s, the well-known Dahlquist criteria. Moreover, the tan(6) (i.e., G" / G', where G" is the loss modulus) should within the range between 0.1 and 1.0 for sufficient cohesive strength to hold together under stress and effective energy dissipation during debonding.

[0145] The alkyne-ML(38.8, 0.26) and LML / ML blends show similar plateau G' at high frequency range (i.e., 2.1 MPa of alkyne-ML(38.8, 0.26), 1.5 MPa of 25 wt% LML blend, 2.3 MPa of 50 wt% LML blend and 3.1 MPa of 75 wt% LML blend at 100 rad / s, respectively). The value of plateau modulus is highly depending on the entanglements in the rubbery matrix, and PyMCL has a reported entanglement molar mass (Me) of 2.9 kg / mol. Therefore, alkyne-ML(38.8, 0.26) with a PyMCL midblock of 33.1 kg / mol should possess well-entangled rubbery matrix and the formation of LML triblock architecture would not increase the entanglement density in the blends, leading to similar plateau G' observed at high frequency range in alkyne-ML(38.8, 0.26) and LML / ML blends, akin to what was reported for SIS / SI blends.

[0146] I ntriguingly, under same processing history, the alkyne-ML(38.8, 0.26) (Figure 29), 25 wt% LML (Figure 30a) and 50 wt% LML (Figure 30b) show a relaxation at low frequency range and are more dissipative as reflected by a high tan(6) detected (i.e., 0.47 of alkyne-ML(38.8, 0.26), 0.28 of 25 wt% LML blend, and 0.25 of 50 wt% LML blend at 1 rad / s, respectively). Differently, the 75 wt% LML blend didn't show such relaxation and a tan(6) as 0.09 at 1 rad / s, which is similar to the case of pure LML triblock copolymers as thermoplastic elastomer. The increase of LML mass fraction proportionally decreased the tan(6) values and enhanced the elasticity of the blends, while the dangling PyMCL ends of alkyne-ML(38.8, 0.26) could relax at long relaxation time that allow the drop of G' at low frequency range and a more liquid-like, viscoelastic behavior. By manipulating the LML mass fraction in the blends, the G' at 1 rad / s was tuned from 0.91 MPa of alkyne-ML(38.8, 0.26) to 0.94 MPa of 25 wt% LML blends, 1.35 MPa of 50 wt% LML blends, and 2.67 MPa of 75 wt% LML blends. Therefore, tuning the molecular architecture in polyester block copolymer blends affords a convenient but useful method to optimize their viscoelasticproperties. Unfortunately, the G' at 1 rad / s of pristine alkyne-ML(38.8, 0.26) and all LML / ML blends are higher than the aforementioned Dahlquist criteria (i.e., 0.3 MPa at 1 rad / s), highlighting the importance of adding tackifiers to enable more effective surface wetting for PSA applications.Adhesive testing

[0147] Standard test methods used for peel adhesion, loop tack adhesion, and shear strength were PSTC:101, ASTM:D1695, and PSTC:107, respectively. The polished stainless steel panel (PSTC 304 BRT, 18 Gauge), high density polyethylene (HDPE, Polymershapes) panels, and PET panels (Polymershapes) were used as the adherent for adhesion testing. The adhesion data of the sticky note (Postit®, 3M), office tape (Scotch® Magic™, 3M), duct tape and electrical tape (Scotch® 22, 3M) were used from previous reports. 180° peel test: a 1 cm wide strip of the PSA coated-PET film was adhered to a panel using a 2 kg rubber roller. The sample was tested by a Shimadzu ASG-X tensile tester at a peel rate of 305 mm / min. The peel force was recorded as the plateau force. The test was performed at least three times and averaged across the samples except for the occasional clear outlier samples. Loop tack test: a 1 cm wide strip of the PSA coated-PET film was made into a teardrop shaped loop and mounted to the upper grip of the tensile tester while a stainless steel panel was mounted on the lower grip. Then the loop was gently lowered forming a contact area of 1 cm xl.5-2 cm. The tack force was monitored while the upper grip was lifted at a rate of 305 mm / min. The tack force was recorded as the maximum measure force. The test was performed at least three times and averaged across the samples except for the occasional clear outlier samples. Shear resistance test: A PSA coated-PET film was adhered to a stainless steel panel forming a contact area of 2.54 cm x 2.54 cm, and pressed by a rubber roller. A 1000 g weight was applied to the sample, and the time to failure (weight drop) was recorded, and averaged across at three samples.

[0148] The adhesion properties of the PSAs were then investigated in terms of their peel force, loop tack force, and shear resistance time on stainless steel substrates, as seen in Figures 31, 33, 34 and Tables 11 and 13, below. As expected from viscoelastic window analysis above, the PSAs from neat LML(76.6, 0.27) exhibited low peel and loop tack forces regardless of processing history (i.e., no detectable force for samples tested after solvent casting, 0.83 ±0.17 N / cm of peel force and 0.60 ± 0.09 N / cm of loop tack force for samples after 170°C annealing, 0.18 ± 0.02 N / cm of peel force and 0.07 ± 0.02 N / cm of loop tack force after two-step annealing) (Table 11 and Table 13), which is attributed to its high G' and low tan(6) values. Moreover, owing to the poor adhesion to the substrate, these PSAs exhibited low shear resistance and typically failed adhesively in less than one hour, underscoring the need for tackifier.

[0149] Figure 31 specifically shows (a) 180° peel adhesion properties and (b) loop tack adhesion properties on stainless steel substrates of LML(76.6, 0.27) and blends of LML(76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature. Horizontal dotted lines indicate the adhesion properties of commercial adhesives. All of the peel and loop tack adhesion tests were performed at a rate of 305 mm / min.

[0150] The addition of tackifier significantly improved the peel and loop tack forces of PSAs. For instance, after two-step annealing, the peel forces increased to 0.64 ± 0.17 N / cm (20 wt% tackifier), 2.32 ± 0.10 N / cm (33 wt% tackifier), and 2.79 ± 0.28 N / cm (43 wt% tackifier) (Figure 31 and Table 11, below), which is comparable to commercial tapes.Table 11

[0151] Table 11 is a summary of adhesion properties of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooping to room temperature. In the instance of peel adhesion values, all adhesives failed via adhesive failure mode. With respect to shear, if no failure was detected after 240 hours, then the experiment was manually terminated.

[0152] The dilution of chain entanglements in the rubbery PyMCL matrix by the tackifier contributed to lower G' and more effective substrate wetting during bonding, while the microphase separated PLLA domains provided cohesive strength to allow fibril formation and extension, and desired adhesive failure mode during debonding. Moreover, these features also yielded excellent shear resistance and no failure was observed over 240 hours. Interestingly, increasing from 33 to 43 wt% tackifier produced only modest improvement in peel and loop tack forces than increasing from 20 to 33 wt%. The phase separation of tackifier in the 43 wt% blend may signify a saturation threshold for adhesion property improvement with tackifier loading.

[0153] In addition to linear viscoelastic properties, it is important to note that the debonding process of PSAs also involves substantial chain stretching and is highly affected by their mechanical properties atlarge strain. To understand the large-strain, nonlinear elastic behaviors of alkyne-ML(38.8, 0.26) and LML / ML blends in PSA debonding process, replicate samples for each formulation were subjected to tensile testing at the extension rate same as the following 180° peel test (i.e., 305 mm / min). Representative tensile curves and results were shown in Figure 32 and Table 12.Table 12

[0154] The pristine alkyne-ML(38.8, 0.26) without effective PyMCL bridgings is soft and of low ductility, with an average stress at break (SBreak) of 0.28±0.05 MPa and an average strain at break (eBreak) of 77.2%±2.8%. As a consequence, the lack of strong cohesive strength and ductility in the alkyne- ML(38.8, 0.26) may not allow effective formation and extension of adhesive fibril during PSA debonding process, suggesting low peel force and unfavorable cohesive failure (i.e., with adhesive residues left on adherend), and thus, excluding its application as PSAs. The incorporation of 25 wt% LML in the blend significantly increased the tensile strength and ductility, producing an average SBreak of 1.06±0.05 MPa and an average eBreak of 853.3% ± 71.1%. Moreover, in 25 wt% LML blend, strain softening was observed at intermediate strain, followed by strain hardening at high strain, which is similar to the SIS / SI blends with low SIS mass fraction. It is important to note that most SIS triblock copolymers form bridging PI midblocks without dangling ends, and the addition of SI diblocks of half the molar mass of the SIS triblocks linearly reduced the concentration of bridging PI chains in the SIS / SI blends.

[0155] Further increase of the LML mass fraction lead to a continuous enhanced tensile strengths, more profound strain hardening effects started at lower strain, and reduced eBreak of 649.3%±29.0% of 50 wt% LML blends and 457% ± 7.8% of 75 wt% LML blends, which also resembles to the widely investigated SIS / SI blends with high SIS triblock mass fractions or pure SIS triblock copolymers. By systematically tuning the LML mass fractions, the nonlinear mechanical properties of LML / ML blends could be readily varied to suit PSA applications.

[0156] The specific processing history of PSAs results in distinctive microstructures and mechanical properties without affecting their chemical characteristics and molar mass, which produces distinct adhesion properties. In this context, PSAs from the blend with 33 wt% tackifier will be used as an example to discuss and reveal the effects of processing history, while the results of other samples are included inboth Table 13 and Figure 33. Figure 33 shows a (a) 180° peel adhesion properties and (b) loop tack adhesion properties on stainless steel substrates of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, or solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature. The horizontal blue lines indicate the adhesion properties of commercial adhesives; and all peel and loop tack adhesion tests were performed at a rate of 305mm / min. Table 13

[0157] The LML (76.6, 0.27) had values that were not measurable due to a small adhesion (or tack) force. When the >240 value is shown it indicates that no failure after 240 hours, and then the experiment was manually terminated. Specifically, the solvent cast PSA showed the lowest peel and loop tack forces (i.e., 0.79 ± 0.16 N / cm and 0.90 ± 0.07 N / cm, respectively), attributed to incomplete microphase separation and high G' and low tan(6) values. The first annealing at 170°C for 60 min drastically improved the peel and loop tack forces of the PSA to 5.80 ± 0.57 N / cm and 3.29 ± 0.32 N / cm, respectively. With enhanced microphase separation, amorphous PLLA domains and potentially reduced G', the effective substrate wetting and energy dissipation during debonding likely contributed to the more than 7-fold enhancement in peel force. Annealing the PSAs at temperatures below 170°C for 60 min did not providesimilar enhancement in peel force and in fact led to lower peel force, as is seen in Figure 34. In Figure 34, the 180° peel adhesion properties on stainless steel substrates of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at different temperatures for 60 minutes, and rapid cooling to room temperature are shown. No annealing below 170°C for 60 min provided acceptable peel force values. All peel adhesion tests were performed at a rate of 305 mm / min. As depicted in Figure 23, the semicrystalline PLLA domains after solvent casting exhibited a melting temperature around 160°C, suggesting that the PLLA end-blocks should be fully melted during annealing to provide sufficient mobility to achieve more complete microphase separation. Cold crystallization of PLLAs occurring at those annealing temperatures (80-140°C) may have increased G' leading to less efficient substrate wetting, leading to reduced peel forces observed (Figure 34).

[0158] To elucidate whether enhanced microphase separation or reduced crystallinity is the major reason of enhanced adhesion properties of corresponding PSAs after 170°C annealing, a blend of 33 wt% tackifier with aLML (78.5, 0.22) containing atactic PLA domains was prepared under same conditions and procedures. Specifically, the solvent casting of a PSA containing aLML (78.5, 0.22) with 33 wt% tackifier showed a peel force of 1.08 ± 0.19 N / cm, which is slightly higher but similar to that of the blend of LML(76.6, 0.27) with 33 wt% tackifier, as seen in Figure 35. In Figure 35, 180° peel adhesion properties on stainless steel substrates of blends of aLML (78.5,0.22) with 20-43 wt% tackifier after solvent casting, or solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature. All peel adhesion tests were performed at a rate of 305 mm / min. After annealing at 170°C, the peel force increased to 2.90 ± 0.42 N / cm, indicating the enhanced microphase separation during high-temperature annealing as an important reason for the improvement in the adhesion properties of PSA (Figure 35). The small differences in peel forces from these two blends containing the same amount of tackifier may result from the different molar masses and compositions between aLML (78.5, 0.22) and LML (76.6, 0.27). Shear resistance was also measured and values can be seen in Figure 36. Specifically referring to Figure 36, shear resistance on stainless steel substrates of blends of LML (76.6, 0.27) and aLML (78.5, 0.22) with 20-43 wt% tackifier after solvent casting, or solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature. For certain samples, no failure after 240 hours, and then the experiment was manually terminated.

[0159] A renewable rosin ester tackifier (Sylvalite RE 80HP) was blended with alkyne-ML(38.8, 0.26) and LML / ML blends to dilute the entanglements in the PyMCL rubbery matrix and promote the interfacial adhesion on substrate. The mass fraction of tackifier was kept at 20 wt% of the PSAs to avoid potentially imperfect mixing between tackifier and PyMCL midblocks. For convenience, the PSAs were prepared byblending all compounds in chloroform, solvent casting via a wire wound rod on polyethylene terephthalate) (PET) film (40 pm, Chemlnstruments), and drying under nitrogen flow for 48h at room temperature, resulting in PSA film thicknesses around 80 pm. The adhesion properties of the PSAs were then characterized in terms of their peel force, failure mode in peel adhesion test and shear resistance time on stainless steel substrates (Figure 37 and Table 14).

[0160] The correlation of LML mass fractions with peel force shows a volcano-shape plot (Figure 37a). With 25 wt% or 50 wt% LML in the LML / ML blends, the tackified PSA showed obvious increase in peel force as 2.78±0.47 N / cm and 1.98±0.37 N / cm, while tackified PSA from 75 wt% LML in the LML / ML blends slightly reduce the peel force to 0.86±0.61 N / cm. Moreover, the peel adhesion failure mode was shifted from cohesive failure to favorable adhesive failure without adhesive residue left on the substrate after peeling. At low LML mass fractions, the LML / ML blends maintained the dissipative characteristic from pure ML diblocks and possessed low G' that promotes the interfacial adhesion on substrate during PSA bonding. On the other hand, as indicated by the high ductility in tensile test, the presence of LML triblocks drastically enhanced the cohesive strength of the PSA and so likely enabled the effective fibril extension during PSA debonding. Collectively, the more sufficient interfacial adhesion and enhanced cohesive strength contributed to improved peel adhesion force and a change from cohesive failure to adhesive failure. However, when LML triblocks dominated the composition (i.e., in the case of 75 wt% LML in LML / ML blends), the high G' and low tan(6) simultaneously reduced the interfacial adhesion via poor surface wetting, thereby leading to decreased peel force, which is similar to the case of solvent-cased PSA with pure LML triblocks and 20 wt% tackifier above (i.e., 0.35±0.02 N / cm). Therefore, by systematically manipulating the LML triblock mass fraction in the blends, the adhesion properties of tackified PSA can be tuned in a predictable manner.Table 14

[0161] Figure 38 is a graphical representation of aging of 180° peel adhesion properties on stainless steel substrates of blend of LML (76.6, 0.27) with 33 wt% tackifiers after solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature. All peel adhesion tests were performed at a rate of 305 mm / min. As can be seen in this figure, after first annealing at 170°C, the PSA of LML (76.6, 0.27) with 33 wt% tackifier exhibited aging behavior and significant drop of peel force to 2.99 ± 0.17 N / cm after storing under ambient conditions for 60 days. Amorphous PLA embrittles rapidly after processing due to the physical aging via structural relaxation and when in block copolymers with PyMCL this process could be retarded. After storing the PSAs under ambient conditions over 7 days, the DSC traces in Figure 25 suggested the amorphous PLLA started to crystalize and produced a melting endotherm around 160°C. Figure 39 is DSC traces on an aging of blend of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, and rapid cooling to room temperature (first heating, 10°C / min; vertically shifted for clarity). The enthalpy of the melting continued to grow with storage time. As a consequence, the formation of semicrystalline PLLA domains with potentially reduced failure by chain pullout from the PLLA domains in the PSAs during debounding process may vary their adhesion properties, which motivates further treatment of PSAs to eliminate this aging behavior while maintaining attractive adhesion properties.

[0162] The second annealing of the PSA at 100°C is a useful way to solve this dilemma by incorporating semicrystalline PLLA domains after achieving enhanced microphase separation during first annealing and accelerating PLLA aging. Even though the increased crystallinity of PLLA yielded a lower starting peel force compared to that of one-step 170°C annealing, the peel force remained stable after storing under ambient conditions over 60 days (i.e., 1.71 ± 0.21 N / cm) as seen in Figure 40. Figure 40 shows the aging of 180° peel adhesion properties on stainless steel substrates of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature. All peel adhesion tests were performed at a rate of 305 mm / min. Compared to solvent casting PSAs with similar crystallinities, the PSAs subjected to two-step annealing still exhibited a roughly 3-fold increase in peel force (i.e., 2.32 ± 0.10 N / cm versus 0.79 ± 0.16 N / cm), which can be ascribed to the enhanced microphase separation, lower G' and higher tan(6) values. After 170°C annealing, the PSAs of blends with over 33 wt% tackifier failed via cohesive failure during peel testing, highlighting the insufficient cohesive force in the PSAs provided by the largely amorphous PLLA domains. In contrast, after two-step annealing, all PSAs with semicrystalline PLLAs domains experienced adhesive failure during peel testing and left no residue on the substrate, serving as promising candidates to solve the "adhesive residue" problem described above. Figure 41 is a graphicalrepresentation of 180° peel adhesion properties on PET and HDPE substrates of blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature. All peel adhesion tests were performed at a rate of 305 mm / min. Furthermore, as is seen in Figure 41, peel tests of PSAs after twostep annealing on substrates with low surface energy (polyethylene terephthalate (PET) and high-density polyethylene (HDPE)) were also conducted to demonstrate that the as prepared PSAs can be used for different adherent surfaces.

[0163] To further improve the adhesion properties of the LML / ML blend, the tackified PSAs were subjected to a two-step annealing process (i.e., first above the melting temperature of PLLA at 170 °C for 60 minutes and second at 100°C to cold-crystallize the PLLA) following the above steps. The shear resistance of the PSAs didn't significantly change after such two-step annealing (Figure 42 and Table 15), possibly owing to the abundance of dangling PyMCL ends in the rubbery matrix. On the other hand, similar to our previous results, the enhanced microphase separation and semicrystalline PLLA domains contributed to the substantially enhanced peel forces after annealing (Figure 43 and Table 15). For instance, the peel forces of tackified PSAs were increased to 2.37±0.48 N / cm (alkyne-ML(38.8, 0.26)), 4.1110.16 N / cm (25 wt% LML in LML / ML blends), 3.6610.33 N / cm (50 wt% LML in LML / ML blends) and 1.5310.28 N / cm (75 wt% LML in LML / ML blends), which is comparable to many commercial products.

[0164] In addition, two different methods to prepare LML / ML blends with 50 wt% LML for PSA applications were demonstrated. First, LML(74.0, 0.25) and ML(37.5, 0.22) were synthesized by sequential ROTEPs with similar compositions and arm length by using 1,4-benzenedimethanol and benzyl alcohol as initiator, respectively. Molecular characteristics of LML(74.0, 0.25) and ML(37.5, 0.22) can be found in Table 5. The as-prepared LML(74.0, 0.25) and ML(37.5, 0.22) were then blended together in chloroform to form a LML / ML blend of 50 wt% LML. On the other hand, 1,4-benzenedimethanol and benzyl alcohol were added together with a 1 to 2 molar ratio to form LML / ML blends of 50 wt% LML via sequential ROTEPs. The similar chemical characteristic of these two initiators would like yield ML and LML with similar compositions and arm length. The molar mass of PyMCL was controlled by the molar ratio of monomer to hydroxyl group of the initiators (i.e., 250 to 1) and a conversion over 95%, producing roughly 30 kg / mol PyMCL, which is similar to the length of PyMCL per arm in the other two methods. The fPLLA was controlled by the amount of L-lactide monomer added and a high conversion of monomer in the second ROTEP. The molecular characteristic of LML / ML blends synthesized from the third method can be found in Table 16. Unfortunately, the precise LML mass fraction in the blend couldn't be determined due to the monomodal peak shape in SEC trace (Figure 44).

[0165] The solvent-casted PSAs of these two LML / ML blends were prepared with additional 20 wt% tackifier following same procedure noted above before 180° peel adhesion test, and named as route 2 and route 3 in Table 17. Intrigui ngly, under same processing conditions and with same amount of tackifier, the peel forces of PSAs from these two routes were similar to that of route 1 (i.e., 1.65±0.25 N / cm from route 2 and 1.21±0.52 N / cm from route 3), and all PSAs failed via adhesive failure. The small difference among different routes may come from the different compositions and molar masses, and errors in LML mass fractions. Therefore, regardless of preparation method, PSAs from LML / ML blends with optimized LML mass fractions should manifest similar, improved adhesion properties compared to that of pure LML triblock or ML diblock copolymers.Table 15Table 16Table 17Hydrolytic degradation test

[0166] PSA coated-PET film was cut into 1 cm x 1 cm square before dispersing in a vial of either ~20 ml 1 M NaOH aqueous solution. The vials were then put into an oven at 45 °C. 50 pL aliquots at varioustime points were taken out from the vials, diluted with 9950 pL deionized water before total organic carbon (TOC) measurement using a Shimadzu TOC-L analyzer. Controlled experiments of PET films were also conducted under same conditions. Note: Hydrolytic degradation tests were also conducted in ~20 mL IM HCI aqueous solution and ~20 mL artificial seawater (pH = 8.1) at 45 °C. Although the PSA films turned translucent (after 15 days in IM HCI aqueous solution and after 7 days in artificial seawater, respectively), no significant change in TOC measurement was observed in 90 days.

[0167] As mentioned above, the polyester block copolymers are found to be readily degradable under relatively mild conditions, enzymatic catalysis, or simulated industrial composting conditions, which may provide sustainable alternatives for nondegradable commercial PSAs. The degradation experiments were monitored by total organic carbon (TOC) analysis to quantify hydrolyzed products that leached out into the solution (Figure 45-47). Specifically referring to Figure 45, the hydrolytic degradation studies in 1 M NaOH aqueous solution at 45°C of LML (76.6, 0.27) and blends of LML (76.6, 0.27) with 20-43 wt% tackifier after solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°C for 5 minutes, and rapid cooling to room temperature are shown. The total organic carbon (TOC) content on the left y-axis is the ratio of measured organic carbon content (right y-axis) in the aqueous solutions to the theoretical carbon content of the LML (76.6, 0.27) and blends. The data points and error bars represent median and range for triplicate experiments, respectively.

[0168] Figure 46 is a graphical representation of hydrolytic degradation studies in 1 M NaOH aqueous solution at 45°C of (a) PET films and (b) Sylvalite tackifier powders. The total organic carbon (TOC) content is the ratio of measured organic carbon in the aqueous solutions to the theoretical carbon content of the PET films and Sylvalite tackifier powders. Similar to above, the data points and error bars represent median and range for triplicate experiments, respectively. The control experiments of PET films without PSA were conducted under same conditions and showed no significant degradation in 24 days (Figure 46(a)).

[0169] As depicted in Figure 45, the PSAs composed of neat LML (76.6, 0.27) showed almost 100% degradation in 15 days, affirming the excellent hydrolytic degradability of this all-aliphatic polyester block copolymer under basic conditions. The transparent PSAs turned opaque in 1 day and was almost completely gone from the substrate after 15 days. Processing history did not noticeably affect the hydrolytic degradation, as is seen in Figure 47. Figure 47 depicts the hydrolytic degradation studies in 1 M NaOH aqueous solution at 45°C of blends of LML (76.6, 0.27) with 33 wt% tackifier after solvent casting (square); solvent casting, first annealing at 170°C for 60 minutes and then rapid cooling to room temperature (circle); solvent casting, first annealing at 170°C for 60 minutes, second annealing at 100°Cfor 5 minutes and rapid cooling to room temperature (triangle). The total organic carbon (TOC) content is the ratio of measured organic carbon in the aqueous solutions to the theoretical carbon content of the blends. The data points and error bars represent median and range for triplicate experiments, respectively.

[0170] However, the addition of tackifier lead to slightly reduced degradation kinetics, possibly owing to the increased hydrophobicity of the blends with tackifier. Moreover, the hydrolysis of PSAs from the blends reached to plateaus below 100% degradation. The detected TOC plateau values are proportional to the weight fractions of LML (76.6, 0.27) in the blends, indicating that tackifier is likely non-degradable under these conditions, or the degraded products are insoluble in aqueous solution. Control experiment of Sylvalite tackifier powders were also performed under the same conditions (Figure 46(b)). In 24 days, TOC measurements suggested that less than 30% of tackifier was detected in aqueous solution with large variations, which is likely due to the heterogeneous dispersion of small tackifier powders in the aqueous solution and limited water solubility of tackifier and its degradation products. Even though rosin esters generally have low molar mass and allow in vivo biodegradation, their high hydrophobicity has been found to significantly slow their hydrolytic in vitro degradation in aqueous solution. Therefore, the hydrolytic degradation experiments may not exactly reflect the biodegradability of as prepared PSAs under composting conditions, but highlight the importance of selecting desired degradation conditions and engineering ready degradability in each component of a fully degradable PSA.

[0171] Pristine LML triblocks were found to be completely degradable via hydrolytic degradation under exactly same conditions, enzymatic catalysis, or biodegradation in simulated industrial composting conditions. Under basic conditions, all transparent PSAs turned opaque in 1 day and were detached from the PET substrate after 10 days, forming white particles suspended in the solution. As shown in Figure 48, the hydrolytic degradation of tackified PSAs from LML / ML blends of 50 wt% LML lead to a fast increase in TOC values during the first 7 days and reached to plateaus around 80% degradation after 15 days, affirming the excellent hydrolytic degradability of LML-based polyester block copolymer blends under basic conditions. Increasing the LML mass fraction didn't change the TOC plateau values (Figure 49), but slightly reduced the degradation kinetics, possibly owing to the longer time that LML needed to be degraded into water-soluble or dispersible products. In previous study, PSAs from tackified LML triblock copolymers also experienced incomplete degradation under this condition, likely attributing to the inaccurate reflect of biodegradability of rosin ester tackifier via hydrolytic degradation. Therefore, the LML / ML blends maintained the ready hydrolytic degradability of polyester-based polymers, while affords enticing tunability in molecular architecture for optimizing their adhesion properties as degradable PSA.

[0172] In summary, degradable PSAs were demonstrated from an all aliphatic LML triblock copolymer and its blends with a renewable tackifier. The effects of processing history and tackifier loading on the microstructures, crystallinities, thermal properties, mechanical properties, and adhesion properties of the PSAs were systematically investigated, providing a potentially useful roadmap for the future design of polyester based PSAs. After two-step annealing, PSAs of the blend of LML (76.6, 0.27) and 33 wt% tackifier exhibited a 2.32±0.10 N / cm peel force in 180° peel adhesion test, a 1.33±0.22 N / cm loop tack force, and no failure in shear resistance test after 240 hours. The readily degradability of LML triblock copolymers also contributed to accessible hydrolytic degradation behaviors of the PSAs in 1 M NaOH aqueous solution at 45°C. In this context, these results indicate that LMLs, and potentially many other polyester block copolymers, with excellent elastomeric properties and degradability can be carefully engineered to afford enticing combination of renewability, property competitiveness, and degradability in PSA applications.

[0173] Further, LML / ML all-aliphatic polyester block copolymers blends were successfully prepared from combining sequential ROTEPs and copper-catalyzed alkyne-azido cycloaddition. The LML mass fraction in the blends can be readily tailored from 25 wt% to 75 wt% via tuning the stoichiometric ratio of bifunctional linker to alkyne terminations on ML diblock copolymer. This provided a convenience and robust strategy to prepare LML / ML blends with same composition and arm length, but distinctive molecular architectures. The effects of LML mass fractions on the microstructures, crystallinities, thermal and mechanical properties of the blends were systematically investigated. By blending with additional 20 wt% of a renewable tackifier, the application of these LML / ML blends on hydrolytically degradable PSAs was demonstrated and showed widely tailorable adhesion properties that correlated to the LML mass fractions. With optimized 50 wt% of LML in the original LML / ML blends, the tackified PSAs exhibited simultaneously improved interfacial adhesion and cohesive strength owing to the balance of dangling and bridging PyMCL chains in the rubbery matrix, thereby producing a 1.98±0.37 N / cm peel force and desired adhesive failure mode in 180° peel adhesion test as well as a shear resistance of 518±163 minutes. After additional two-step annealing, the peel force of the same PSA can be further improved to 3.66±0.33 N / cm, which is comparable to many commercial products. The hydrolytic degradability of these LML / ML blends were accessed and evaluated in 1 M NaOH aqueous solution at 45 °C. In this context, our results indicate the optimization of molecular architecture in LML / ML blends, and potentially many other polyester block copolymer blends, allows for readily engineering of their properties for PSA applications with enticing renewability, degradability and competitive performance.

[0174] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and / or ordinary meanings of the defined terms.

[0175] The articles "a" and "an," as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean "at least one." The phrase "and / or," as used herein in the specification and in the claims (if at all), should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and / or" should be construed in the same fashion, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and / or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and / or B", when used in conjunction with open-ended language such as "comprising" can refer, in some embodiments, to A only (optionally including elements other than B); in other embodiments, to B only (optionally including elements other than A); in yet other embodiments, to both A and B (optionally including other elements); etc. As used herein in the specification and in the claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of" or "exactly one of," or, when used in the claims, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e. "one or the other but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0176] As used herein in the specification and in the claims, the phrase "at least one," in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least oneof A and / or B") can refer, in some embodiments, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in other embodiments, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet other embodiments, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

[0177] An embodiment is an implementation or example of the present disclosure. Reference in the specification to "an embodiment," "some embodiments," "some embodiments," "one particular embodiment," or "other embodiments," or the like, means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the invention. The various appearances "an embodiment," "some embodiments," "some embodiments," "one particular embodiment," or "other embodiments," or the like, are not necessarily all referring to the same embodiments.

[0178] If this specification states a component, feature, structure, or characteristic "may", "might", or "could" be included, that particular component, feature, structure, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, that does not mean there is only one of the element. If the specification or claims refer to "an additional" element, that does not preclude there being more than one of the additional element.

[0179] As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers may be read as if prefaced by the word "about" or "approximately," even if the term does not expressly appear. The phrase "about" or "approximately" may be used when describing magnitude and / or position to indicate that the value and / or position described is within a reasonable expected range of values and / or positions. For example, a numeric value may have a value that is + / -0. % of the stated value (or range of values), + / -!% of the stated value (or range of values), + / -2% of the stated value (or range of values), + / - % of the stated value (or range of values), + / - 10% of the stated value (or range of values), etc. Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

[0180] Additionally, any method of performing the present disclosure may occur in a sequence different than those described herein. Accordingly, no sequence of the method should be read as a limitation unless explicitly stated. It is recognizable that performing some of the steps of the method in a different order could achieve a similar result.

[0181] In the claims, as well as in the specification above, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "composed of," andthe like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of" and "consisting essentially of" shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures.

[0182] In the foregoing description, certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be implied therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed.

[0183] Moreover, the description and illustration of various embodiments of the disclosure are examples and the disclosure is not limited to the exact details shown or described.

Claims

CLAIMSWe claim:

1. A composition comprising: a triblock copolymer comprising: poly(L-lactide)-block-poly(y-Methyl-e-caprolactone)- blockpoly(L-lactide) (LIX / I L); and a tackifier.

2. The composition of claim 1, wherein the composition comprises between 15 and 45 wt% of the tackifier.

3. The composition of claim 1, wherein the composition comprises between 55 and 85 wt% of the triblock copolymer.

4. The composition of claim 1, wherein the triblock copolymer is the reaction product of Tin (II) 2- ethylhexanoate, L-lactide, and a macroinitiator containing y-Methyl-e-caprolactone.

5. A construction comprising: a layer of the composition of claim 1, and a substrate.

6. The construction of claim 5, wherein the layer of the composition and the substrate together have a total thickness of about 20-lOOpm.

7. The construction of claim 6, wherein the layer of the composition has a first thickness and the substrate has a second thickness and a ratio of the first thickness to second thickness is about 1:1.

8. The construction of claim 5, wherein the substrate has a first side and a second side opposite the first side and the substrate is a face film.

9. The construction of claim 8, wherein the construction exhibits a peel adhesion, when the layer of the composition is coated onto the face film, of greater than 0.5 N / cm when tested in accordance with PSTC:101 at a rate of 305mm / min when the article is applied to stainless steel.

10. The construction of claim 9, wherein the construction exhibits a peel adhesion, when the layer of the composition is coated onto the face film, of greater than 2.2 N / cm when tested in accordance with PSTC:101 at a rate of 305mm / min when the article is applied to stainless steel.

11. The construction of claim 8, wherein the construction exhibits a loop tack adhesion, when the layer of the composition is coated onto the face film, of greater than 0.18 N / cm when tested in accordance with ASTM:D1695 at a rate of 305mm / min when the article is applied to stainless steel.

12. The construction of claim 11, wherein the construction exhibits a loop tack adhesion, when the layer of the composition is coated onto the face film, of greater than 1.1 N / cm when tested in accordance with ASTM:D1695 at a rate of 305mm / min when the article is applied to stainless steel.

13. The construction of claim 8, wherein the construction exhibits a shear strength when the layer of the composition is coated onto the face film, of greater than 240 hours when tested in accordance with to PSTC:107 when the article is applied to stainless steel.

14. The construction of claim 8, wherein the face film is selected from the group consisting of: polyolefins, polyvinyl chloride, polyethylene terephthalate, polystyrene, polyurethane, polymethacrylate, polycarbonate, paper, cardboard, and combinations thereof.

15. The construction of claim 5, further comprising a liner, wherein the substrate has a first side and a second side opposite the first side, and the liner has a first face and a second face opposite the first face, and the composition is located between the second side of the substrate and the first face of the liner.

16. The liner of claim 15, wherein the liner is selected from the group consisting of: paper, treated paper, polymer film, and treated polymer film. J. The construction of claim 15, further comprising a release liner located longitudinally below the composition and longitudinally above the first face of the liner.

18. A method comprising: providing a composition comprising a triblock copolymer comprising: poly(L-lactide)-block- poly(y-Methyl-e-caprolactone))-blockpoly(L-lactide) (LIX / I L) and a tackifier; coating the composition onto a substrate resulting in a construction; and adhering the substrate to an article.

19. The method of claim 18, further comprising: dissolving the composition into a solvent prior to coating onto the substrate; removing the solvent after coating onto the substrate resulting in a dried construction; annealing the dried construction at a temperature between 150-200°C for at least one hour; and quenching the dried construction in less than 5 minutes to a temperature below 25°C.

20. The method of claim 19, further comprising: annealing a second time the dried construction after the quenching step, at a temperature between 90-160°C for at least five minutes; and quenching the dried construction a second time, in less than 3 minutes to a temperature below 25°C.

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