Methods of reversible-addition fragmentation chain transfer metathesis and block copolymers therefrom

Abstract

The subject matter described herein is directed to RAFT polymerization methods for preparing block copolymers and the block copolymers prepared therefrom.

Description

[0001] METHODS OF REVERSIBLE-ADDITION FRAGMENTATION CHAIN TRANSFER METATHESIS AND BLOCK COPOLYMERS THEREFROM

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] [1] This application claims the benefit of priority to United States Provisional Patent Application No. 63 / 694,529, filed on September 13, 2024; and United States Provisional Patent Application No. 63 / 666,855, filed on July 2, 2024, the content of each of which is incorporated by reference herein in its entirety for all purposes.

[0004] FIELD

[0005] [2] The subject matter described herein is directed to RAFT polymerization methods for preparing block copolymers and the block copolymers prepared therefrom.

[0006] BACKGROUND

[0007] [3] Reversible-Addition Fragmentation chain Transfer (RAFT) polymerization, is a polymerization technique that exhibits characteristics associated with living polymerization. Living polymerization is generally considered in the art to be a form of chain polymerization in which irreversible chain termination is substantially absent. An important feature of living polymerization is that polymer chains will continue to grow while monomer is provided and the reaction conditions to support polymerization are favorable. Polymers prepared by RAFT polymerisation can advantageously exhibit a well-defined molecular architecture, a predetermined molecular weight and a narrow molecular weight distribution or low polydispersity.

[0008] [4] RAFT controlled radical polymerization is one of the most widely exploited platforms for controlled chain-growth polymerization of various free radical monomers, featured by its versatility and practical ease in implementation (J. Chiefari etal., Living Free-Radical Polymerization by Reversible Addition-Fragmentation Chain Transfer: The RAFT Process. Macromolecules 31, 5559-5562 (1998); S. Perrier, 50th Anniversary Perspective: RAFT Polymerization — A User Guide. Macromolecules 50, 7433-7447 (2017). The RAFT process is mediated by Chain Transfer Agents (CTA, or RAFT agents) which seed the polymerization and govern the chain transfer exchange via an intermediate (J. Chiefari et al., Thiocarbonylthio Compounds (SC(Z)S-R) in Free Radical Polymerization with Reversible Addition-Fragmentation Chain Transfer (RAFT Polymerization). Effect of the Activating Group Z. Macromolecules 36, 2273-2283 (2003); Y. K. Chong etal., Thiocarbonylthio Compounds [SC(Ph)S-R] in Free Radical Polymerization with Reversible Addition-Fragmentation Chain Transfer (RAFT Polymerization). Role of the Free-Radical Leaving Group (R). Macromolecules 36, 2256- 2272 (2003)). In the RAFT process, it is the fragmentation of the R-group present in these CTAs that is the main initiating source to seed new chains for chain-growth. This chain transfer process is mediated by a thiocarbonyl thio group (S=C-S) that carries an auxiliary Z-group, thereby modifying the reactivity.

[0009] [5] More activating Z-groups like dithiobenzoate or trithiocarb onate are required to make the C=S bond reactive enough to control more activated monomers (MAMs) that polymerize with stable radical centers. However, these Z-groups lead to stabilized chaintransfer intermediate adducts, resulting in retardation during polymerization, especially for less activated monomers (LAMs) that polymerize with highly reactive centers. To mitigate this issue, less activating Z-groups such as xanthates and dithiocarbamates are selected for LAMs to prevent retardation. This dichotomy limits the construction of well- defined block copolymers of different classes.

[0010] [6] Therefore, while RAFT controlled radical polymerization has been explored since its discovery, applications are generally limited by the lack of tunability of the polymer backbone, which is inherent to its chain-growth mechanism. What is therefore needed and not addressed in the art are methodologies that can be widely exploited to address these challenges, and usher in a new generation of materials that were previously unattainable. The present disclosure addresses these shortcomings in the art.

[0011] BRIEF SUMMARY

[0012] [7] In certain embodiments, the subject matter described herein is directed to a RAFT polymerization process, comprising: forming a first polymer by allowing a plurality of first monomers (Ml) to react with a first CTA comprising a R1 group and a Z1 group to form the first polymer comprising residues of Ml and the R1 and Z1 groups; forming a second polymer by allowing the first polymer to react with a second CTA comprising a R2 group and a Z2 group to form the second polymer comprising the residues of Ml and the R1 and Z2 groups; forming a block copolymer by allowing a plurality of second monomers (M2) to react with the second polymer to form the block copolymer, wherein the block copolymer comprises M1-M2 blocks and R1 and Z2.

[0013] [8] In certain embodiments, the M1-M2 blocks are MAM-LAM blocks.

[0014] [9] In certain embodiments, the subject matter described herein is directed to block copolymers comprising Ml -M2 blocks.

[0015]

[0010] In certain embodiments, the subject matter described herein is directed to block copolymers comprising MAM-LAM blocks.

[0016]

[0011] In certain embodiments, the subject matter described herein is directed to block copolymers having a structure of Formula P-1 : wherein, Rl, Ml, n, M2 and Z2 are as described herein.

[0017]

[0012] Other embodiments are also described.

[0018] BRIEF DESCRIPTION OF THE FIGURES

[0019]

[0013] Figure 1 depicts block copolymers via RAFT metathesis.

[0020]

[0014] Figure 2 depicts a mechanism of RAFT polymerization.

[0021]

[0015] Figure 3 is an overview of Z-group functionality.

[0022]

[0016] Figure 4 describes selection of Z-group.

[0023]

[0017] Figure 5 depicts an erstwhile limitation of MAM / LAM RAFT copolymerization.

[0024]

[0018] Figure 6 depicts RAFT metathesis, which is a platform where R / Z groups are exchanged between two or more CTAs.

[0025]

[0019] Figure 7A-B depict A: end group functionalization (ACS Macro Lett. 2023, 12, 1306-1310), and B: Depolymerization (Chem. Sci. 2024, 15, 4910-4919).

[0026]

[0020] Figure 8 depicts utilizing RAFT metathesis for the preparation of MAM / LAM copolymers.

[0027]

[0021] Figure 9 depicts the effect of R / Z-group with RAFT metathesis equilibrium.

[0028]

[0022] Figure 10A-B describe the end-group functionalization predictability using equilibrium driven RAFT metathesis and its effect on stoichiometry; A: Theoretical yield equation; and B: plot of theoretical yield of a metathesis reaction as a function of initial stoichiometry and equilibrium constant.

[0029]

[0023] Figure 11 shows application of RAFT metathesis for Z-group exchange.

[0030]

[0024] Figure 12 depicts the relationship between equilibrium RAFT metathesis and several exemplary R groups.

[0025] Figure 13 depicts the relationship between equilibrium RAFT metathesis and several exemplary R groups.

[0031]

[0026] Figure 14 depicts exemplary blocks for block copolymer synthesis using RAFT metathesis as described herein.

[0032]

[0027] Figure 15A-F depict data on the investigation of the Equilbirum of RAFT metathesis with library of CTAs with different R / Z groups. Each study (A-F) was carried out in pairs from both sides of the equilibrium as the initial reactants. Partial molar fraction of trithiocarb onate species of the right-hand side of the equilibrium is plotted respect to all trithiocarb onate species

[0033]

[0028] Figure 16 depicts SEC analysis of block copolymerization of PPEGA-PVB.

[0034] DETAILED DESCRIPTION

[0035]

[0029] Disclosed herein are unique approaches to RAFT (Reversible Addition Fragmentation chain Transfer) polymerization that provide the ability to design block copolymers with unique backbone properties that were previously synthetically challenging. RAFT polymerization 1 is a widely recognized platform in polymer chemistry due to its user-friendly nature, versatility, and robustness, which is attributed to its modular nature and high tolerance towards various functionalities (G. Moad, E. Rizzardo and S. H. Thang, Aust. J. Chem., 2012, 65, 985-1076; S. Perrier, Macromolecules, 2017, 50, 7433-7447; N. Corrigan, K. Jung, G. Moad, C. J. Hawker, K. Matyjaszewski and C. Boy er, Prog. Polym. Sci., 2020, 111, 101311). Certain RAFT method and polymers therefrom are disclosed in WO2023 / 034335, which is hereby incorporated by reference in its entirety. The RAFT process is facilitated by Chain Transfer Agents (CTA), characterized by the fragmentation of the R-group present in these CTAs, which acts as the main initiating source to seed new chains for chain-growth (Y. K. Chong, J. Krstina, T. P. T. Le, G. Moad, A. Postma, E. Rizzardo and S. H. Thang, Macromolecules, 2003, 36, 2256-2272). This chain transfer process is mediated by a thiocarbonyl thio group (S=C-S) that carries an auxiliary Z-group, thereby modifying the reactivity (J. Chiefari, R. T. A. Mayadunne, C. L. Moad, G. Moad, E. Rizzardo, A. Postma and S. H. Thang, Macromolecules, 2003, 36, 2273-2283).

[0036]

[0030] Typically, more activating Z-groups like dithiobenzoate or trithiocarb onate are required to make the C=S bond reactive enough to control more activated monomers (MAMs) that polymerize with stable radical centers. However, these Z-groups lead to stabilized chain-transfer intermediate adducts, resulting in retardation during polymerization, especially for less activated monomers (LAMs) that polymerize with highly reactive centers. To mitigate this issue, less activating Z-groups such as xanthates and dithiocarbamates are selected for LAMs to prevent retardation (K. G. E. Bradford, L. M. Petit, R. Whitfield, A. Anastasaki, C. Bamer-Kowollik and D. Konkolewicz, J. Am. Chem. Soc., 2021, 143, 17769-17777). This dichotomy limits the construction of well- defined block copolymers of different classes.

[0037]

[0031] Fundamentally, the RAFT process involves the dynamic exchange between two reactive radical species. This allows the exchange between fragmentating R-group and thiocarbonyl thio bearing Z-groups in the presence of two (or more) (macro)CTAs. A procees for end-group functionalization has been termed ‘RAFT interchange’ (O. R. Courtney, S. M. Clouthier, S. Perrier, J. Tanaka and W. You, ACS Macro Letters, 2023, 12, 1306-1310). However, the process described herein is directed to preparation of block copolymers and can be better described as RAFT metathesis. The process of 'RAFT metathesis' presents a unique and promising avenue that remains largely under-studied. The practical utility of RAFT metathesis was first demonstrated by Perrier et al. (S. Hakkinen, B. Dyer, A. Kerr and S. Perrier, Polym. Chem,, 2022, 13, 479-484), who prepared a graft copolymer through a RAFT metathesis between a macro-CTA and a linear polymer backbone with CTA side chains tethered via the Z-group. They also demonstrated the interchange of two different graft copolymers with different graft lengths, resulting in a convergence to a single species. More recently, the present Applicant demonstrated end-group functionalization of RAFT polymers through RAFT metathesis by employing Z-groups with tethered functionality (Courtney, et al.) Further advancements include successful partial depolymerization though RAFT metathesis of RAFT step-growth polymers via Z-group approach (J. Li, J. Tanaka, Q. Li, C. J. Jing Wang, S. Sheiko, S. M. Clouthier, J. Zhu and W. You, Chemical Science, 2024, 15, 4910- 4919).

[0038]

[0032] One pivotal question in the study of RAFT metathesis revolves around the significance of the equilibrium constant of the process, coined as the interchange equilibrium constant (XIE). Previous studies suggest an interchange equilibrium constant of “1” (XIE = 1), implying no discernible difference in free energy between reactants and products (AG = 0). However, the universal validity of this assessment remains uncertain. Thus, described herein is a mathematical theorem and conditions when this initial evaluation of the interchange equilibrium constant holds true and when it does not.

[0039]

[0033] Moreover, when the equilibrium constant deviates from “1,” it indicates a thermodynamic preference for the reaction to proceed in one direction. We envisioned by elucidating this fundamental process, we can harness equilibrium driven RAFT metathesis for optimal block copolymerization.

[0040]

[0034] Demystifying expected outcomes of RAFT metathesis with equivalent R or Z groups: When only considering the radical chain transfer (via RAFT process), the interchange-equilibrium constant can be treated as the product of the individual chaintransfer equilibrium constants (Eq 1).

[0041] ^IE = KE I E 2

[0042]

[0035] In the case of equivalent Z-group reactivity (but different R-group reactivity), mathematically, the equilibrium constant of one chain-transfer can be treated as a reciprocal of the other (XEXI = Tx?'1). Then the product of the two equilibrium constants will therefore result in an overall value of 1 (KEXIKEX2 = 1). In theory, this means the differences in R-group fragmentation efficiencies alone will have no impact on the yield of the RAFT interchange process if equilibrium can be reached. This was evident in our previous work using an equivalent Z-group, where we observed that the RAFT metathesis followed the expected yield, assuming an equilibrium constant of 1. (Courtney et al.)

[0043]

[0036] Similarly, when the fragmenting R-groups can be treated as equivalent reactivities (but with different class of Z-groups), then the individual chain transfer equilibrium constants will be 1 (XEXI = KEX2 = 1) as the fragmentating S-C bond and R* species are identical from both sides of the exchange reaction. Consequently, RAFT interchange between two different Z-groups should not impact the yield at equilibrium if the R-groups are treated as chemically equivalent.

[0044]

[0037] RAFT metathesis with different R and Z-groups: In the case of both R and Z groups being chemically inequivalent, we investigated the RAFT metathesis process between two different CTAs bearing different R and Z groups. Specifically, we screened RAFT metathesis between xanthate and trithiocarb onate CTAs with different R groups. To be thorough, we investigated from either side of the equilibrium using stoichiometrically equivalent CTAs. In theory, it is expected for the resultant mixture to converge into an identical proportion of four species, with the equilibrium constant being reciprocal from the opposite side of the equilibrium.

[0045]

[0038] To assess the equilibrium, we tracked the partial mole fraction of CTAs pair (one from the reactant side and one from product side), for example, Z-group CH next to the trithiocarb onate present in the product and reactant. Initially, we studied the reaction between carboxyl-stabilized secondary and tertiary fragmentation with AIBN as a source of radicals. However, we found the reaction to be notably too slow. We hypothesized that the chain transfer from the less activated Z-group was rate-limiting. Moreover, when the less activating Z-group bore a less fragmentable R-group, the reaction kinetics were significantly halted. To mediate the slow fragmentation, we utilized UV irradiation to photofragment the xanthate CTA directly. Though still rather slow, we observed that the RAFT metathesis converged to one side of the equilibrium, favoring the formation of trithiocarb onate CTA bearing secondary fragmentation.

[0046]

[0039] We carried out further experiments with secondary benzyl fragmentation, which has intermediate stability between the first two R-groups studied. According to our study, it was clear that the equilibrium of RAFT metathesis is driven to the side where the more activated Z-group bears a less fragmentable R-group. We attribute this to the chain transfer equilibrium, with the more activated Z-group dominating the direction of the interchange equilibrium. Following this trend, we lastly explored CTAs with primary benzyl radical fragmentation. According to our theory, xanthate with this R-group would drive the interchange equilibrium to the product side with all the trithiocarb onate CTAs studied, while trithiocarb onate CTA with this fragmentation would result in equilibrium favoring the reactant side. Indeed, we found the equilibrium to follow this trend.

[0047]

[0040] It is worth noting that when starting from the side furthest from the equilibrium, the reaction took significantly longer in our experiments (over 100 hours). Additionally, in some cases, the xanthate CTA was found to degrade during the extended reaction time, which is practically disadvantageous. We reason that the more active Z-group retards the metathesis reaction through a relatively stable chain transfer intermediate adduct. To overcome this kinetic limitation, we hypothesized that using a higher equivalence of the less active Z-group would expedite the metathesis reaction. Indeed, we found the reaction to be completed within 16 hours using 10 equivalents of xanthate relative to trithiocarb onate

[0048]

[0041] Theoretical kinetic approximation of the RAFT interchange equilibrium constant: To better understand the nature of the RAFT interchange equilibrium constant, we initially carried out DFT (Density Functional Theory) calculations to determine the theoretical thermodynamic equilibrium constant (XTD) based on minimum energy landscape of the individual CTAs. Interestingly, we observed some differences in the Gibbs free energy between starting and product CTAs that appeared to lean towards the direction of the equilibrium found in most of our model experiments (Figure 16). However, we found large discrepancy between theoretical and experimental results in some instances. For example, calculations of primary and secondary benzyl fragmentation showed no significant difference when interchanging between xanthate and trithiocarb onate Z-groups and comparison of these pairs with the other CTAs, despite observing considerable differences experimentally. In one case the RAFT metathesis between Xanthate bearing secondary carboxylic acid and trithiocarbonate bearing secondary benzyl group, experimentally showed favorability for the product side (K > 1), however it was computed to have less thermodynamically favorable product (K < 1).

[0049]

[0042] As described herein, RAFT metathesis facilitated by such a radical chain transfer process represents a kinetic equilibrium (rather than a thermodynamic equilibrium), which may not necessarily reflect the intrinsic minimum energy state (i.e., XIE XTD). For the RAFT metathesis to proceed, chain transfer must occur from each CTA. However, due to inherent differences in thiocarbonyl thiol reactivity, the chain transfer process occurs significantly more frequently with the trithiocarb onate CTA than with the xanthate CTA. This suggests that we may approximate the equilibrium constant of the metathesis primarily based on minimum energy calculations of the chain-transfer equilibrium of the more activating Z-group (i.e., XIE ~ XEXI, where XEXI is the chain transfer equilibrium constant for the more activating Z-group), assuming negligible contributions from the less reactive Z-group and while neglecting the metathesis from photoactivation-deactivation pathway. Approximation may be most valid for CTAs with significantly different Z- group reactivities.

[0050]

[0043] Nonetheless, when comparing the yield of the metathesis experiments, we find that the experimental values align more closely with our predicted chain transfer equilibrium constant than with the overall thermodynamic equilibrium constant. However, in most cases, these predicted values are overestimated because they neglect the chain-transfer equilibrium constant from the less activating Z-group. Therefore, the predicted equilibrium yield from Txi can be considered as the minimum theoretical yield when Txi < 1 and the maximum theoretical yield when Txi > 1.

[0051]

[0044] Equilibrium theorem: yield as function of stoichiometry and equilibrium constant: Typically, when estimating yield from an equilibrium reaction involving reagents with different equivalence, approximations are made, such as assuming x is small for small K values.11However, to accurately predict the yield of the RAFT metathesis reaction, we found it necessary to advance the equilibrium theorem beyond these approximations. Therefore, we derived an equation that directly describes the partial mole fraction at equilibrium as a function of the initial stoichiometry of reagents and the equilibrium constant (see Supporting Information for derivation).

[0052]

[0045] In the derived equation, the partial mole fraction of the product on the left-hand side represents an arbitrary pair of CTAs from the product side (denoted as [C]) and the reactant side (denoted as [A]) of the equilibrium equation. The initial stoichiometric difference between the two starting CTAs ([A]o and [B]o) is accounted for by the term “r,” which represents the ratio (r = [B]o / [A]o), indicating the equivalence of B with respect to A.

[0053]

[0046] This general equation can be applied to compute the expected partial fraction of trithiocarb onate species in our model experiments, and more importantly, to predict the yield of CTA end group exchange in RAFT polymerization. Moreover, the utility of the equation can be illustrated by the semi-logarithmic plot of yield across ranges of stoichiometry and different equilibrium constants (Figure 17). This plot illustrates that a high conversion (99%) can be easily achieved with a moderate stoichiometric excess of 10 equivalents of exchanging CTA, even when the equilibrium constant is moderate (K = 10).

[0054]

[0047] In the case of matching R-group or Z-group reactivity, we would expect a K value of 1, as discussed above. Therefore, under these conditions, Eq 2 would simplify to Eq 3, leading to the same formulation as in our previous work (Courtney et al.)

[0055] [B]o_ r [B]o+ [A]or + 1

[0056]

[0048] CTA end-group exchange by RAFT metathesis:_We prepared various polymers with MAMs using trithiocarbonate-based CTAs. This Z-group allows excellent control over MAMs such as styrene, acrylates, and acrylamides, provides moderate control over methacrylates, and is known to cause severe retardation with LAMs like vinyl esters.

[0057]

[0049] We initially prepared polystyrene (PSty) in bulk with CTAl([Sty]o / [CTAo = 100) using V-40 as the initiator at 85 °C. To ensure minimum loss of end-group through termination, we targeted relatively high CTA to initiator ratio ([CTA]o / [I]o = 20) to ensure high degree of livingness (G. Gody, T. Maschmeyer, P. B. Zetterlund and S. Perrier, Macromolecules, 2014, 47, 639-649). After 16 hours, the moderate conversion was achieved (p = 34 %) with excellent molecular weight control (Mn= 3.5k, D = 1.13) that matches number-average molecular weight in agreement with expected value (A / n,th = 3.8k).

[0058]

[0050] We investigated RAFT metathesis with this polymer (PSty-TTC) with 10 equivalences of various xanthate-based CTAs: XAN2, XANB2 and XAN1. The reactions were mediated by UV light in dioxane as the solvent, targeting a total CTA concentration of 1 M. As anticipated, the yield trends followed the expected order, favoring xanthate CTAs with a lower fragmentable R-group compared to the polymer's end-group. Using XAN2, we observed a 10% yield in end-group exchange, which aligns with the predicted minimum yield of 3.5% based on the model XEXI value (XEXI'1= 7940). Notably, by rearranging Equation 2, we calculated the experimental equilibrium constant (XIE- 1= 891). Matching the R-group reactivity with XANB2 (XIE = 1), results in a yield of 88 %, matching closely to the expected yield of 90 % with Eq 3. Finally, using XAN1, which was predicted to have a theoretical maximum yield of 98% from a XEXI of 4.79, resulted in a quantitative yield.

[0059]

[0051] Next adopting a literature procedure for high chain end fidelity (A. Rasines Mazo, T. N. Tran, W. Zhang, Y. Meng, A. Reyhani, S. Pascual, L. Fontaine, G. G. Qiao and S. Pioge, Polym. ('hem,, 2020, 11, 5238-5248), poly(poly ethylene glycol acrylate) (PPEGA) was prepared via blue light mediated photo-iniferter RAFT polymerization using CTA1 ([PEGA]o / [CTA]o = 20) and dioxane as the solvent ([PEGA]o = 1 M). After 2 hours the polymerization reached 86 % conversion with excellent molecular weight control.

[0060]

[0052] We next subjected this polymer (PPEGA-TTC) to RAFT metathesis with 10 equivalences of various xanthate-based CTAs same as above. XAN2 and XANB2 anticipated to give low end-group exchange yield, was found to yield 15 % (theoretical minimum 1.6 %) and 61% (theoretical minimum 73 %) respectively, following the expected trend. While XAN1 providing yield of 89% was consistent expected yield of 91 % based on XIE = 1 due to matching R-group reactivity (Eq. 3). Finally, RAFT metathesis with XANB1 gave quantitative end-group exchange (theoretical maximum 98 %).

[0061]

[0053] It is noteworthy that we prepared poly(methylmethacrylate) (PMMA) using 4- cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl] pentanoic acid (CDTPA) as the CTA, which contains a trithiocarbonate Z-group. However, RAFT metathesis of PMMA-TTC with XAN2, XANB2, and XAN1 resulted in the removal of the end-group as confirmed by 'H-NMR. This is likely due to the rapid photodegradation of the xanthate-capped PMMA. Similarly, Agosto and Desterac reported the instability of xanthate-capped PMMA in their study (C. Bergerbit, B. Farias-Mancilla, L. Seiler, V. Monteil, S. Harrisson, F. D' Agosto and M. Destarac, Polym. Chem,, 2019, 10, 6630-6640). Interestingly, SEC analysis showed no discernable differences.

[0062]

[0054] To further demonstrate scope of RAFT metathesis, we lastly tested end-group exchange with acrylamide polymer. We prepared Poly(4-Acryloylmorpholine) (PNAM) with TTC1 ([NAM]o / [CTA]o = 50) using AIBN as the initiator ([CTA]o / [I]o = 40) at 70 °C and dioxane as the solvent ([NAM]o = 3 M). After 2 hours the polymerization reached 99 % conversion (DPth = 50, A / n,th = 7.3k) with controlled molecular weight Mn= 2.8k, D = 1.22). According to our DFT calculations, primary benzyl radial and trithiocarb onate with secondary amide fragmentation has a favorable chain transfer equilibrium (XEXI = 45, theoretical maximum yield of 99.8 % with r = 10). Using the same conditions above RAFT metathesis of PNAM-TTC with XANB1 indeed gave a quantitative conversion by ‘H-NMR.

[0063]

[0055] Lastly, we employed RAFT metathesis to prepare MAM-LAM block copolymer that is challenging to prepare with common CTAs. We thought to prepare block polymer of PPEGA and poly(vinyl butyrate) (PVB) as this has never been reported to the best of our knowledge. We prepared xanthate based PPEGA macro-CTA (PPEGA-XAN) through RAFT metathesis with PPEGA-TTC and 10 equivalence of XANB1. Pleasingly we were able to chain-extend with PPEGA-XAN with VB, as evident from shift in molecular weight distribution by SEC analysis. It’s important to note, without the prior RAFT metathesis PPEGA-TTC leads to a complete halt in VB polymerization due RAFT retardation.

[0064]

[0056] The presently disclosed subject matter will now be described more fully hereinafter. However, many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. In other words, the subject matter described herein covers all alternatives, modifications, and equivalents. In the event that one or more of the incorporated literature, patents, and similar materials differs from or contradicts this application, including but not limited to defined terms, term usage, described techniques, or the like, this application controls. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in this field. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This subject matter may, however, be embodied in many different forms and should not be construed as limited to the aspects set forth herein; rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art.

[0065] I. Definitions

[0066]

[0057] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the present application and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. The terminology used in the description of the subject matter herein is for the purpose of describing particular aspects only and is not intended to be limiting of the subject matter. In case of a conflict in terminology, the present specification is controlling.

[0067]

[0058] As used herein, “polymer” refers to the product of a polymerization reaction in which one or more monomers and / or repeat units are linked together. A polymer includes copolymers. Additionally, particular polymers are brush-like, comb-like, branched or hyperbranched, crosslinked, or a mixture thereof.

[0068]

[0059] As used herein, a “CTA” refers to a chain transfer agent and comprises trithiocarb onate group(s) or dithiocarb onate group(s) (including O-esters of dithiocarb onate (xanthates). In certain embodiments, a “CTA residue” means the residue of a group containing a thiocarb onylthio group may refer to the xanthate group — OC(S)S — , and a trithiocarb onate group refers to the group — SC(S)S — . After polymerization, in various embodiments, the residues may be removed to form, for example, a hydroxy -terminated multi-armed polymer. In various embodiments, the residues may be removed, for example, through nucleophilic substitution.

[0069]

[0060] As used herein, the term “less activating” indicates Z groups that lead to more stable chain-transfer intermediates relative to a more activating Z group. As used herein, the term “more activating” indicates Z groups that lead to a less stable chain-transfer intermediate relative to a less activating Z group.

[0070]

[0061] As used herein, “copolymer” refers to a polymer resulting from the polymerization of two or more chemically distinct monomers. A “block copolymer” refers to a polymer comprising blocks of monomers.

[0071]

[0062] As used herein, the term “monomer” means any monomer that is polymerizable or copolymerizable via a radical route. Generally, monomers can be classified as more- activated monomers (MAMs) and less activated monomers (LAMs). MAMs have a vinyl bond conjugated to another double bond, including those of aromatic rings, as well as carbonyl and nitrile groups. Representative monomers of this class include butadiene, isoprene, styrene, vinyl pyridine, (meth)acrylates, (meth)acrylamides, maleic anhydride, mal eimide, and acrylonitrile. LAMs have a double bond adjacent to an electronwithdrawing group such as a nitrogen, oxygen, halogen, or sulfur atom with a lone electron pair, or they have saturated carbons attached to the vinyl carbon atoms. Representative monomers of this class include vinyl acetate, N-vinylpyrrolidone (NVP), vinyl chloride, and alkenes are LAMs. Unsaturated free-radical-polymerizable monomers for use in the present disclosure may be selected from the following unsaturated monomers, among others: (a) vinyl monomers, including vinyl pyrrolidone, vinyl alcohol, halogenated vinyl compounds such as vinyl chloride and vinyl fluoride, vinyl imidazole, vinyl ethers, vinyl esters such as vinyl acetate, acrylonitrile, and vinyl aromatic monomers such as substituted and unsubstituted styrene, (b) alkylene monomers and derivatives, such as ethylene, propylenes (e.g., a-propylene, isopropylene), butylenes (e.g., a-butylene, [3-butylene, isobutylene), pentenes, etc., (c) fluorinated unsaturated monomers including fluorinated alkylene monomers (e.g., tetrafluoroethylene, trifluorochloroethylene, vinylidene fluoride, etc.), (d) (meth)acrylic monomers and derivatives, such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, glyceryl acrylate, glyceryl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, PEG acrylates and PEG methacrylates, for example, PEG methyl ether acrylate and PEG methyl ether methacrylate, acrylamide, methacrylamide, ethacrylamide, and so forth, (e) nitriles including acrylonitrile, and methacrylonitrile, and (f) diene monomers such as 1,3- butadiene, chloroprene, and isoprene, as well as combinations of the foregoing monomers.

[0072]

[0063] The use of “Ml -M2,” “M1 / 2” and the like refers to the presence of a Ml or a M2 monomer. A block of Ml or M2 refers to two or more Ml or M2 monomers, respectively.

[0073]

[0064] The term “alkyl” refers to a straight chain or branched chain saturated hydrocarbyl group. The term “C1-20 alkyl” refers to an alkyl group having 1 to 20 carbon atoms, examples include C1-12 alkyl, C1-10 alkyl, C1-6 alkyl, Ci-4alkyl and C1-3 alkyl groups. Examples of C1-6 alkyl include methyl (Me), ethyl (Et), propyl (Pr), isopropyl (i-Pr), butyl (Bu), isobutyl (i-Bu), sec-butyl (s-Bu), tert-butyl (t-Bu), pentyl, neopentyl, hexyl and the like. Unless the context requires otherwise, the term “alkyl” also encompasses alkyl groups containing one less hydrogen atom such that the group is attached via two positions, i.e. divalent.

[0074]

[0065] As used herein, the term “aryl” refers to an aromatic carbocyclic group having a single ring (e.g., monocyclic) or multiple rings (e.g., bicyclic or tricyclic) including fused systems. As used herein, aryl has 6 to 20 ring carbon atoms (i.e., C6-C20 aryl), 6 to 12 carbon ring atoms (i.e., C6-C12 aryl), or 6 to 10 carbon ring atoms i.e., Ce-Cio aryl). Examples of aryl groups include, e.g., phenyl, naphthyl, fluorenyl and anthryl. Aryl, however, does not encompass or overlap in any way with heteroaryl defined below. If one or more aryl groups are fused with a heteroaryl, the resulting ring system is heteroaryl. If one or more aryl groups are fused with a heterocyclyl, the resulting ring system is heterocyclyl.

[0075]

[0066] As used herein, the term “heteroaryl” refers to an aromatic group having a single ring, multiple rings, or multiple fused rings, with one or more ring heteroatoms independently selected from nitrogen, oxygen, and sulfur. As used herein, heteroaryl includes 1 to 20 ring carbon atoms (i.e., C1-C20 heteroaryl), 3 to 12 ring carbon atoms (i.e., C3-C12 heteroaryl), or 3 to 8 carbon ring atoms (i.e., C3-C8 heteroaryl), and 1 to 5 ring heteroatoms, 1 to 4 ring heteroatoms, 1 to 3 ring heteroatoms, 1 to 2 ring heteroatoms, or 1 ring heteroatom independently selected from nitrogen, oxygen and sulfur. In certain instances, heteroaryl includes 9-10 membered ring systems (9- to 10- membered heteroaryl), 6-10 membered ring systems (6- to 10-membered heteroaryl), 5- 10 membered ring systems (5- to 10-membered heteroaryl), 5-7 membered ring systems (5- to 7-membered heteroaryl), or 5-6 membered ring systems (5- to 6-membered heteroaryl), each independently having 1 to 4 ring heteroatoms, 1 to 3 ring heteroatoms, 1 to 2 ring heteroatoms, or 1 ring heteroatom independently selected from nitrogen, oxygen and sulfur. Examples of heteroaryl groups include, e.g., acridinyl, benzimidazolyl, benzothiazolyl, benzindolyl, benzofuranyl, benzothiazolyl, benzothiadiazolyl, benzonaphthofuranyl, benzoxazolyl, benzothienyl (benzothiophenyl), benzotriazolyl, benzo[4,6]imidazo[l,2-a]pyridyl, carbazolyl, cinnolinyl, dibenzofuranyl, dibenzothiophenyl, furanyl, isothiazolyl, imidazolyl, indazolyl, indolyl, indazolyl, isoindolyl, isoquinolyl, isoxazolyl, naphthyridinyl, oxadiazolyl, oxazolyl, 1- oxidopyridinyl, 1-oxidopyrimidinyl, 1-oxidopyrazinyl, 1-oxidopyridazinyl, phenazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinazolinyl, quinoxalinyl, quinolinyl, quinuclidinyl, isoquinolinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl and triazinyl. Examples of the fused-heteroaryl rings include, but are not limited to, benzo[d]thiazolyl, quinolinyl, isoquinolinyl, benzo[b]thiophenyl, indazolyl, benzo[d]imidazolyl, pyrazolo[l,5-a]pyridinyl and imidazo[l,5-a]pyridinyl, where the heteroaryl can be bound via either ring of the fused system. Any aromatic ring, having a single or multiple fused rings, containing at least one heteroatom, is considered a heteroaryl regardless of the attachment to the remainder of the molecule (z.e., through any one of the fused rings). Heteroaryl does not encompass or overlap with aryl as defined above.

[0076]

[0067] The terms “alkene” and “alkenyl” refer to linear or branched-chain monovalent hydrocarbon radical of two to twelve carbon atoms with at least one site of unsaturation, i.e., a carbon-carbon, sp2double bond, wherein the alkenyl radical includes radicals having “cis” and “trans” orientations, or alternatively, “E” and “Z” orientations. Examples include, but are not limited to, ethylenyl or vinyl ( — CH=CH2), allyl ( — CH2CH=CH2), and the like.

[0077]

[0068] The terms “alkyne” and “alkynyl” refer to a linear or branched monovalent hydrocarbon radical of two to twelve carbon atoms with at least one site of unsaturation, i.e., a carbon-carbon, sp triple bond. Examples include, but are not limited to, ethynyl ( — C=CH), propynyl (propargyl, — CH2OCH), and the like.

[0078]

[0069] The term “halogen” or “halo” refers to atoms occupying group VIIA of the periodic table, such as fluoro, chloro, bromo or iodo.

[0079]

[0070] The term “dalkylamine” refers to -N(alkyl)2.

[0080]

[0071] The term “thiocarb onylthio” refers to an ester group where one or more oxygen atoms have been replaced with a sulphur atom, e.g., a xanthate group may refer to the group — OC(S)S — , and a trithiocarb onate group refers to the group — SC(S)S — .

[0081]

[0072] “Functionalized” as used herein, means the indicated substituent groups are chemically bonded in the main backbone chain or pendant to the main backbone. A “functional unit” as used herein, means a chemical group or moiety used in the chain itself to functionalize the main backbone chain or used pendant to the main backbone chain.

[0082]

[0073] As used herein, the term “residue” or “residue of’ a chemical moeity refers to a chemical moiety that is bound to a molecule, whereby through the binding, at least one covalent bond has replaced at least one atom of the original chemical moiety, resulting in a residue of the chemical moiety in the molecule. A residue can also be depicted as a structure either showing the replaced atom with a bond or the atom prior to replacement.

[0083]

[0074] The term “cleavable” refers to a chemical group or moiety that is chemically labile under normal conditions. The term “non-cleavable” refers to a chemical group or moiety that is chemically stable under normal conditions.

[0084]

[0075] As used herein, a “radical initiator” or “initiator” include, for example, hydrogen peroxide, organic peroxides such as dibenzoyl peroxide, di-t-butyl peroxide, benzoyl peroxide or methyl ethyl ketone peroxide, among others, and azo compounds such as azobisisobutyronitrile (AIBN), or l,l'-azo-bis(cyclohexane-carbonitrile) (ABCN), among others.

[0085]

[0076] As used herein, the term “photocatalyst” refers to a polymerization initiator used in PET-RAFT polymerizations. PET-RAFT initiates via a transfer of triplet excited stated energy or electron from an excited photocatalyst to RAFT agent or RAFT residue, which results in fragmentation to create radicals. The photocatalyst can comprise a closed-shell metalloporphyrin complex. In some non-limiting examples, the polymerization initiator comprises Zn(II) tetraphenylporphyrin (ZnTPP); meso-tetraphenylporphyrin (TPP);

[0086] 5,10,15,20-tetraphenyl-21H,23H-porphine nickel(II) (NiTPP); 5,10,15,20-tetrakis(4- methoxyphenyl)-21H,23H-porphine cobalt(II) (CoTMPP); 5,10,15,20-tetrakis(4- methoxyphenyl)-21H,23H-porphine iron(III) chloride (FeTMPP); palladium(II) octaethylporphyrin (PdOEP); or a combination thereof. In some examples, the polymerization initiator comprises Zn(II) tetraphenylporphyrin (ZnTPP); palladium(II) octaethylporphyrin (PdOEP); or a combination thereof. In some examples, the polymerization initiator comprises Zn(II) tetraphenylporphyrin (ZnTPP). In some examples, the polymerization initiator comprises palladium(II) octaethylporphyrin (PdOEP).

[0087]

[0077] As used herein, “linear polymer” refers to a polymer having side chains that are shorter than the spacer between neighboring side chains along the backbone or main chain of the polymer. When the spacer is negligibly short, “linear polymer” refers to a polymer having side chains that are shorter than the persistence length of the side chains. For example, a polymer chain with side chains, in which the spacer consists of two covalent bonds and side chain persistence length is ten covalent bonds long, is considered as a “linear polymer.” Examples of linear polymers include, but are not limited to, vinyl polymers with relatively short side chains or small side groups. When the side chains become longer than their persistence length, the polymer is no longer considered a linear polymer. Rather, the polymer is now considered a brush / comb polymer as further detailed below. For example, poly(butyl acrylate) with n-butyl side groups is a linear polymer whereas poly(octadecyl acrylate) with n-octadecyl side chains is a brush-like polymer.

[0088]

[0078] As used herein, the term “brush polymer” and the like refers to a polymer block having side chains that are significantly longer than the spacer between neighboring side chains along the backbone or main chain of the polymer. Thus, without wishing to be bound by theory, the side chains can be at least more than two monomeric units long, more than 3 monomeric units long, more than 4 monomeric units long, more than 5 monomeric units long, more than 6 monomeric units long, more than 7 monomeric units long, or more than 8 monomeric units long, so long as the spacer is shorter than the square-root of the side chain length. For example, a brush-like polymer block could have poly(butyl acrylate) side chains with a degree of polymerization of 100 separated by a poly(butyl acrylate) spacer with a degree of polymerization of 2 (2 «< (100)). The chemical nature (i.e., repeat unit) of the side chains and the backbone are not necessarily identical.

[0089]

[0079] As used herein, the term “side chain” refers to a chain pendant to the main polymer chain. Examples of chemical structures of side chains include, but are not limited to homopolymers and copolymers of poly siloxanes, polyacrylates, polymethacrylates, poly ethers, polyolefins (e.g., polyisobutylene, polyethylene, ethyl ene / propylene copolymers), polyoxazolines, poly(glycerol sebacate), poly(a-esters), polyglycolide, polylactides, poly(lactide-co-glycolide), polycaprolactone, poly(ortho esters), polydioxanone, polyanhydrides, polyamides, poly(ester amide)s, polyurethanes, polypropylene fumarate), poly(ethylene terephthalate), polycarbonate, polystyrene, polytetrafluoroethylene) and corresponding derivatives, copolymers and blends. Some examples of chemical composition of brush-like adhesive formulations include polydimethylsiloxane, polyisobutylene, polyp-butyl acrylate), and polyethylene glycol.

[0090]

[0080] As used herein, the term “visible light” refers to light with a wavelength between about 380 nm and about 750 nm, between about 400 nm and about 700 nm, or between about 440 nm and about 650 nm. Near infrared (NIR) light may refer to light with a wavelength between about 750 nm to about 2500 nm. The desired infrared (IR) wavelength range may refer to the wavelength range of IR light that can be detected by a suitable IR sensor (e.g., a complementary metal -oxide semiconductor (CMOS), a charge- coupled device (CCD) sensor, or an InGaAs sensor), such as between 830 nm and 860 nm, between 930 nm and 980 nm, or between about 750 nm to about 1000 nm.

[0091]

[0081] As used herein, the terms “contacting” and “mixing” and the like refer to reagents, such as macromonomers, in close proximity so that a reaction may occur.

[0092]

[0082] As used herein, “ambient temperature” or “room temperature” refers to a temperature in the range of about 20 to 25 °C. As used herein, “heat” refers to a temperature above ambient temperature, for example from about 50 to 200 °C.

[0093]

[0083] As used herein, the term “substantially” refers to the complete or nearly complete extent or degree of a component, or an action, characteristic, property, state, structure, item, or result. The exact allowable degree of deviation from absolute presence of such a component, or an action, characteristic, property, state, structure, item, or result may in some cases depend on the specific context. However, generally speaking, “substantially” will be so near as to have the same overall result as if absolute and total extent or degree were obtained. The use of “substantially” is equally applicable when used in a negative connotation to refer to the complete or near complete lack of a component, or an action, characteristic, property, state, structure, item, or result. For example, a composition that is “substantially free of’ leaching would either completely lack leaching or so nearly completely lacking that the effect would be the same as if it completely lacked leaching. In other words, a composition that is “substantially free of’ leaching may still actually leach as long as there is no measurable effect thereof, for example, trace amounts. As used herein, “essentially free” means a component, or an action, characteristic, property, state, structure, item, or result is not present or is not detectable.

[0094]

[0084] As used herein, the term “predominantly” and “predominant” refer to the reaction product that is produced in the highest quantity or the product that the reaction favors.

[0095]

[0085] As used herein, the term “uniform” means a controlled or tunable amounts of monomers in a block relative to the amounts of monomers in another block as opposed to a random quantity present in a block.

[0096]

[0086] Additional definitions may also be provided below.

[0097] II. RAFT Copolymer Methods and Polymers

[0098]

[0087] In certain embodiments, the subject matter described herein is directed to a RAFT polymerization process, comprising: forming a first polymer by allowing a plurality of first monomers (Ml) to react with a first CTA comprising a R1 group and a Z1 group to form the first polymer comprising residues of Ml and the R1 and Z1 groups; forming a second polymer by allowing the first polymer to react with a second CTA comprising a R2 group and a Z2 group to form the second polymer comprising the residues of Ml and the R1 and Z2 groups; forming a block copolymer by allowing a plurality of second monomers (M2) to react with the second polymer to form the block copolymer, wherein the block copolymer comprises Ml -M2 blocks and R1 and Z2.

[0099]

[0088] In the methods described herein, R1 R2; Z1 Z2; R1 Z1 or Z2; R2 Z1 or Z2.

[0100]

[0089] In certain embodiments, the methods yield predominantly uniform Ml -M2 blocks. In certain embodiments, the methods yield predominantly uniform more specifically described as (Ml)m-(M2)nblocks, wherein m is an integer from 2 to 1,000; or from 2 to 500; or from 2 to 200; or from 2 to 100; or from 2 to 50; or from 2 to 40; or from 2 to 30; or from 2 to 20; or from 2 to 10; or from 2 to 5; and n is an integer from 2 to 1,000; or from 2 to 500; or from 2 to 200; or from 2 to 100; or from 2 to 50; or from 2 to 40; or from 2 to 30; or from 2 to 20; or from 2 to 10; or from 2 to 5.

[0101]

[0090] In certain embodiments, the methods yield predominantly uniform Ml -M2 blocks that are MAM-LAM blocks. In certain embodiments, the methods yield predominantly uniform Ml -M2 blocks that are (MAM)m-(LAM)nblocks.

[0091] The first CTA has a structure of Formula I:

[0102] S

[0103] R1- wherein, R1 and Z1 are as described herein.

[0104]

[0092] The second CTA has a structure of Formula II: wherein, R2 and Z2 are described herein.

[0105]

[0093] In certain embodiments, R1 is selected from the group consisting of where * indicates attachment of the R1 to the -S atom. X, Y and Z are each independently selected from the group consisting of alkyl, H, cyano, halogens (in particular F, Cl or Br), alkene, alkyne, esters, carboxylic acids, (primary, secondary, tertiary) amides, aryl and heteroaryl groups.

[0106]

[0094] In certain embodiments, R2 is selected from the group consisting of where * indicates attachment of the R2 to the -S atom. X, Y and Z are each independently selected from the group consisting of alkyl, H, cyano, halogens (in particular F, Cl or Br), alkene, alkyne, esters, carboxylic acids, (primary, secondary, tertiary) amides, aryl and heteroaryl groups.

[0107]

[0095] In certain embodiments, Z1 is selected from the group consisting of aryl, -S-alkyl and heteroaryl. In certain embodiments, Z1 is selected from the group consisting of phenyl, -S-(Ci-6 alkyl), pyrrolyl and alkyl. In certain embodiments, Z1 is selected from the group consisting of aryl, -S-alkyl and heteroaryl. In certain embodiments, Z1 is selected from the group consisting of phenyl, -S-(Ci-6 alkyl) and pyrrolyl. At the bottom of Figure 14, the three leftmost structures are exemplary Z1 groups.

[0108]

[0096] In certain embodiments, Z2 is selected from the group consisting of -O-aryl; O- alkyl and -dialkylamines. In certain embodiments, Z2 is selected from the group consisting of -O-phenyl; O-(Ci-6 alkyl) and -N-diethyl. At the bottom of Figure 14, the three rightmost structures are exemplary Z2 groups.

[0109]

[0097] In certain embodiments, Ml is a MAM. In certain embodiments, the MAM is selected from the group consisting of butadiene, isoprene, styrene, vinyl pyridine, (meth)acrylates, (meth)acrylamides, maleic anhydride, maleimide, and acrylonitrile. The top left side of Figure 14 depicts exemplary MAMs.

[0110]

[0098] In certain embodiments, M2 is a LAM. In certain embodiments, the LAM is selected from the group consisting of vinyl acetate, N-vinylpyrrolidone (NVP), vinyl chloride, and alkenes. The top right side of Figure 14 depicts exemplary MAMs.

[0111]

[0099] In certain embodiments, the steps of forming a polymer or block copolymer are performed in a solvent in the presence of an initiator and heat.

[0112]

[0100] In certain embodiments, the methods further comprise a step of cleaving a terminal end of the polymer or block copolymer.

[0113]

[0101] In certain embodiments, the subject matter described herein is directed to block copolymers having a structure of Formula P-1 : wherein, Rl, Ml, n, M2 and Z2 are as described herein.

[0114] S

[0115]

[0102] In certain embodiments, the group is removed to produce a terminal hydroxy group.

[0116]

[0103] In certain embodiments, the Ml and M2 blocks can comprise side chains.

[0117]

[0104] Derivation of Tanaka’s Equilibrium Equation:

[0118] K A+B C+D

[0119] In the case of species A reacting stoichiometrically with species of B, to yield simultaneously species C and D in a reversible manner (as shown in general scheme above), the equilibrium constant is given by:

[0120] By defining initial concentration of A as [A]o and, we can express the initial concentration of species B ([B]o) as equivalence with respect to A by defining it as ratio, r as shown below: Eq. S2

[0121] Eq. S3 [B]o— [A]0

[0122] Suppose some change in species A concentration of “x” of species A from its initial concentration (Eq S4). This would result equivalent amount of change in species B (Eq. S5) and equal formation of species C and D (S6)

[0123] Eq. S4

[0124] [A] = [A]o- x

[0125] Eq. S5

[0126] [B] = r[A]0- x

[0127] Eq. S6

[0128] [C] = [D] = x

[0129] Substitution of these terms above Eq. S4-S6) into the general equilibrium formula (Eq SI), results in term equilibrium formula in terms of initial concentration of A with equivalence of B:

[0130] Eq. S7 x2K -([A]o - x)(r[A]„ - x)

[0131] The following equation can be simply rearranged as follows: x2

[0132] ([A]o- x)(r[A]0- x) = — Eq. S8 A

[0133] The left-hand side can be expanded, and the term x2 / / f can be subtracted from both sides:

[0134] Next, the term [A]ox and x2can be factorized:

[0135] Finally, the entire equation can be divided by [A]o2resulting in:

[0136] The final equation (Eq. SI 1) is a quadric equation in terms of In the traditional quadratic formula (left-hand side of Eq. S12), the real solution is yielded when the plusminus term is plus. However, no solutions exist when K = 1 as the 2ndorder term is zero (coefficient a), which results in an undefined solution as it results in zero divided zero. Therefore, alternative quadratic equation (right-hand side of Eq. S12), is employed where such that solution exists for across all values of K.

[0137] For: aa)2+ ba) + c = 0

[0138] Eq. S12 X

[0139] Letting a> = — — solving the quadratic equation (Eq. Si l) with the alternative quadratic l lo formula (Eq. S12), yields the solution where minus-plus is term is minus, where a = X

[0140] Note ^j- is also partial mole fraction of C (or D) with respect to pair A, that can be expressed by substituting [C] and [A] with Eq S4 and Eq S6 below:

[0141] [C] x > x Eq. S14

[0142] [C] + [A] x + [A]o— x [A]o

[0143] In terms of the RAFT metathesis applied to CTA end-group, species A can be defined as the original polymer species while species C can be defined as polymer with the exchange CTA end group. Therefore represents fraction of the polymers with the desired exchanged end-group (yield), that can be predicted from equilibrium constant (K) and stoichiometry of the exchanging CTA from Eq. S13.

[0144] Note, Eq. S13 can be rearranged such that K is the subject of the formula:

[0145] Thus, with Eq. S15 equilibrium constant (or N in the case of RAFT metathesis) can be determined from molar fraction of the C or D species with respect to A.

[0146]

[0105] The General Procedures and Examples provide exemplary methods for preparing compounds, copolymers and compositions. Those skilled in the art will appreciate that other synthetic routes may be used to synthesize the compounds. Although specific starting materials and reagents are depicted and discussed in the Schemes, General Procedures, and Examples, other starting materials and reagents can be easily substituted to provide a variety of derivatives and / or reaction conditions. In addition, many of the exemplary compounds prepared by the described methods can be further modified in light of this disclosure using conventional chemistry well known to those skilled in the art.

[0147]

[0106] The subject matter disclosed herein is directed to the following non-limiting embodiments: 1. A RAFT polymerization process for preparing a block copolymer, comprising forming a first polymer by allowing a plurality of first monomers (Ml) to react with a first CTA comprising a R1 group and a Z1 group to form the first polymer comprising residues of Ml and the R1 and Z1 groups; forming a second polymer by allowing the first polymer to react with a second CTA comprising a R2 group and a Z2 group to form the second polymer comprising the residues of Ml and the R1 and Z2 groups; forming a block copolymer by allowing a plurality of second monomers (M2) to react with the second polymer to form the block copolymer, wherein the block copolymer comprises Ml -M2 blocks and R1 and Z2.

[0148] 2. The RAFT polymerization process of embodiment 1, wherein R1 R2; Z1 Z2; R1 7^ Z1 or Z2; R2 ^ Zl or Z2.

[0149] 3. The RAFT polymerization process of embodiment 1 or 2, wherein the process yields predominantly uniform M1-M2 blocks.

[0150] 4. The RAFT polymerization process of any one of embodiments 1-3, wherein the process yields predominantly uniform (Ml)m-(M2)nblocks, wherein m is an integer from 2 to 1,000; or from 2 to 500; or from 2 to 200; or from 2 to 100; or from 2 to 50; or from 2 to 40; or from 2 to 30; or from 2 to 20; or from 2 to 10; or from 2 to 5; and n is an integer from 2 to 1,000; or from 2 to 500; or from 2 to 200; or from 2 to 100; or from 2 to 50; or from 2 to 40; or from 2 to 30; or from 2 to 20; or from 2 to 10; or from 2 to 5.

[0151] 5. The RAFT polymerization process of any one of embodiments 1-4, wherein the first CTA has a structure of Formula I:

[0152] S R1-

[0153] 6. The RAFT polymerization process of any one of embodiments 1-5, wherein R1 is selected from the group consisting of: wherein, * indicates attachment of the R1 to the -S atom; and,

[0154] X, Y and Z are each independently selected from the group consisting of alkyl, H, cyano, halogen, alkene, alkyne, ester, carboxylic acid, (primary, secondary, tertiary) amides, aryl and heteroaryl. 7. The RAFT polymerization process of any one of embodiments 1-6, wherein Z1 is selected from the group consisting of aryl, -S-alkyl and heteroaryl.

[0155] 8. The RAFT polymerization process of embodiment 7, wherein Z1 is selected from the group consisting of phenyl, -S-(Ci-6 alkyl) and pyrrolyl.

[0156] 9. The RAFT polymerization process of any one of embodiments 1-8, wherein the second CTA has a structure of Formula II:

[0157] 10. The RAFT polymerization process of any one of embodiments 1-9, wherein R2 is selected from the group consisting of : wherein, * indicates attachment of the R2 to the S atom; and,

[0158] X, Y and Z are each independently selected from the group consisting of alkyl, H, cyano, halogen, alkene, alkyne, ester, carboxylic acid, (primary, secondary, tertiary) amides, aryl and heteroaryl.

[0159] 11. The RAFT polymerization process of any one of embodiments 1-10, wherein Z2 is selected from the group consisting of -O-aryl; O-alkyl and -dialkylamines.

[0160] 12. The RAFT polymerization process of embodiment 11, wherein Z2 is selected from the group consisting of -O-aryl; O-alkyl and -dialkylamines.

[0161] 13. The RAFT polymerization process of embodiment 12, wherein Z2 is selected from the group consisting of -O-phenyl; O-(Ci-6 alkyl) and -N-diethyl.

[0162] 14. The RAFT polymerization process of any one of embodiments 1-13, wherein Ml is a MAM.

[0163] 15. The RAFT polymerization process of embodiment 14, wherein the MAM is selected from the group consisting of butadiene, isoprene, styrene, vinyl pyridine, (meth)acrylates, (meth)acrylamides, maleic anhydride, maleimide, and acrylonitrile.

[0164] 16. The RAFT polymerization process of any one of embodiments 1-15, wherein M2 is a LAM.

[0165] 17. The RAFT polymerization process of embodiment 16, wherein the LAM is selected from the group consisting of vinyl acetate, N-vinylpyrrolidone (NVP), vinyl chloride, and alkenes. 18. The RAFT polymerization process of any one of embodiments 1-17, wherein the forming a polymer or block copolymer is performed in a solvent in the presence of an initiator and heat.

[0166] 19. The RAFT polymerization process of any one of embodiments 1-18, further comprising cleaving a terminal end of the polymer or block copolymer.

[0167] 20. A block copolymer having a structure of Formula P-1 : wherein, Rl, Ml, n, M2 and Z2 are as described herein.

[0168]

[0107] The following examples are offered by way of illustration and not by way of limitation.

[0169] EXAMPLES

[0170] Materials and Methods

[0171]

[0108] Unless stated all reagents were purchased from commercial suppliers and used as received. The initiator V-40 and Azobisisobutyronitrile (AIBN) were recrystallized with methanol. Methyl Methacrylate (MMA), Polyethylene methyl ether acrylate (PEGA), styrene, 4-Acryloylmorpholine (NAM) and anhydrous dioxane were passed through activated basic aluminum oxide and discarded after several uses. All NMR spectrums were recorded on a Bruker 400 MHz and 600 MHz spectrometer in CDCh. All NMR spectrums were processed using Mestrenova. Conventional SEC analysis of the crude polymerization mixture was carried out using polystyrene calibration in THF with calibration range of molecular weight from 195k to 270. These were measured using Waters 2695 separations module liquid chromatograph equipped with two Agilent ResiPore columns (linear SEC separation range up to 500 k) maintained at 35 °C, and a Waters 2412 refractive index detector. THF (without additives) was used as the mobile

[0172] phase and the flow rate was set to 1 mL / min. All the samples were run with 100 pL injection volume.

[0173] Preparation of CTAs

[0174]

[0109] The trithiocarb onate CTAs, TTC2, TTCB2, TTC1 and TTCB1, were prepared according to literature. 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (CDTPA) for MMA polymerization was purchased from Boron Molecular.

[0175] Potassium O-ethyl carb onodi thioate was prepared as following procedure:

[0176]

[0110] A I L round bottom flask was charged with potassium hydroxide (33.18 g, 0.591 mol) and 450 mL of ethanol. Once fully dissolved the solution was cooled to 0 °C and carbon disulfide (45 g, 35.7 mL, 0.591 mol) was added dropwise via addition funnel. A yellow solid crashed out that was subsequently collected via vacuum filtration. Solids were rinsed forward with diethyl ether and the product was allowed to dry overnight giving a pale yellow solid (66.21 g, 64%). The product was used without any further purification.

[0177]

[0111] Synthesis of 2-((ethoxycarbonothioyl)thio)-2-methylpropanoic acid (XAN2, an exemplary second CTA):

[0178]

[0112] A 500 mL round bottom flask equipped with stir bar / plate was charged with sodium hydroxide (6.18 g, 0.154 mol) and water (250 ml). After the dissolution of the sodium hydroxide, the mixture was left to chill in ice bath and purged with argon for 10 minutes. To this mixture 2-bromo-2-methylpropanoic acid (26.87 g, 0.161 mol) followed by potassium O-ethyl carb onodi thioate (26.00 g, 0.163 mol) was added under argon flow and stirring. The mixture was then left to stir overnight at room temperature. 160 ml of 1 M HC1 solution was then added to the mixture, and the product was extracted using DCM (3 x 100 ml). The combined organic extracts were washed with brine 3 times (3 x 200 ml). The organic phase was dried over magnesium sulfate and concentrated in vacuo. The resulting crude was recrystallized from hexane to give white crystalline solid (4.1 g, 12.3 % yield). 'H-NMR (600 MHz, CDCI3) 84.61 (q, J= 7.1 Hz, 2H), 1.65 (s, 6H), 1.38 (t, J= 7.2 Hz, 3H).

[0179]

[0113] Synthesis of 2-((ethoxycarbonothioyl)thio)propanoic acid (XAN1, an exemplary second CT A):

[0180]

[0114] To a 250 L round bottom flask equipped with stir bar / plate was charged potassium O-ethyl carb onodi thioate (17.7 g, 0.111 mol) and 120 mL of ethanol. A rubber septum was attached and argon was allowed to flow for 15 minutes. After this time 2- bromopropionic acid (14.0 g, 0.0921 mol) was added dropwise via syringe. After 22 hours the reaction was a cloudy white mixture. The precipitates were removed via filtration and the filtrate was concentrated in vacuo. The residue redissolved in DCM and washed with brine (3 x lOOmL). The organic phase was dried over magnesium sulfate and concentrated in vacuo. The resulting residue was diluted with lOOmL of hexanes and placed in the freezer overnight, yielding white crystalline (5.72 g, 32%). 'H-NMR (600 MHz, CDCI3) 6 11.57 (s, 1H), 4.64 (qd, J = 7.1, 4.2 Hz, 2H), 4.41 (q, J= 7.5 Hz, 1H), 1.59 (d, J= 7.5 Hz, 3H), 1.41 (t, J= 7.2 Hz, 3H).

[0181]

[0115] Synthesis of O-ethyl S-(l-phenylethyl) carb onodi thioate (XANB2, an exemplary second CT A):

[0182]

[0116] To a 250 mL 1 neck round bottom flask equipped with stir bar / plate was charged potassium O-ethyl carb onodi thioate (18.0 g, 0.112 mol) and 120 mL of ethanol. A rubber septum was attached and argon was allowed to flow for 15 minutes. After this time 1- bromoethylbenzene (18.9 g, 0.102 mol) was added dropwise via syringe. After 22 hours the mixture was concentrated in vacuo. The residue suspended in DCM and washed with brine (3 x 100mL). The organic phase was dried over magnesium sulfate and concentrated in vacuo. The resulting crude was purified by column chromatography with DCM as the eluent, yielding a clear oil (11.1 g, 48%). 'H-NMR (400 MHz, CDCI3) 6 7.41 (dt, J= 6.1, 1.5 Hz, 2H), 7.41 - 7.33 (m, 2H), 7.29 (td, J= 6.6, 1.5 Hz, 1H), 4.93 (q, J = 7.1 Hz, 1H), 4.64 (q, J= 7.1 Hz, 2H), 1.74 (d, J= 7.1 Hz, 3H), 1.41 (t, J= 7.1 Hz, 3H).

[0183]

[0117] Synthesis of S-benzyl O-ethyl carb onodi thioate (XANB1, an exemplary second CT A):

[0184]

[0118] To a 1 L 1 neck round bottom flask equipped with stir bar / plate was charged potassium O-ethyl carb onodi thioate (18.4 g, 0.105 mol) and 480 mL of acetone. A rubber septum was attached and argon was allowed to flow for 15 minutes. After this time 1- bromoethylbenzene (15.0 g, 0.0877 mol) was added dropwise via syringe. After 1 hour the mixture was concentrated in vacuo. The residue suspended in DCM and washed with brine (3 x 100 mL). The organic phase was dried over magnesium sulfate and concentrated in vacuo. The resulting crude was purified by vacuum distillation, yielding a clear oil (9.09 g, 49 %). 'H-NMR (600 MHz, CDC13) 8 7.40 - 7.32 (m, 4H), 7.32 - 7.27 (m, 1H), 4.69 (q, J = 7.1 Hz, 2H), 4.40 (s, 2H), 1.45 (t, J= 7.1 Hz, 3H).

[0185] Preparation of Polymers

[0186]

[0119] Preparation of PMMA-TTC (an exemplary first polymer)

[0187]

[0120] Initiator V-40 (8.14 mg, 0.033 mmol) and CDTPA (402.8 mg, 0.97 mmol) was charged into a 20 ml scintillation vial, followed by methyl methacrylate (10 g, 1.0 mol). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing the reaction mixture in a heat block set to 85 °C for 16 hours. The integration of vinyl protons at 5.56 ppm were measured relative to CH2 next to the trithiocarb onate (Z-group) at 3.34 ppm (CDPTA) and 3.25 ppm (polymer end-group) to determine monomer conversion. After 16 hours the monomer conversion reached 37.2 % (DP* = 37, A n,th = 4. Ik, L% = 97.9 %). The polymer was isolated by precipitation into hexane twice and then dried in vacuum oven (3.847 g, 37% yield). Conventional SEC analysis (dRI, THF) reveals Mn= 4.5k, D = 1.28 (PSty calibration).

[0188]

[0121] Preparation of PSty-TTC (an exemplary first polymer)

[0189]

[0122] Initiator V-40 (11.7 mg, 0.048 mmol) and TTC1 (228.9 mg, 0.96 mmol) was charged into a 20 ml scintillation vial, followed by styrene (10 g, 0.96 mol). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing the reaction mixture in a heat block set to 85 °C for 16 hours. The integration of vinyl protons at 5.25 ppm were measured relative to CH2 next to the trithiocarb onate (Z-group) at 3.35 ppm (TTC1) and 3.26 ppm (polymer end-group) to determine monomer conversion. After 16 hours the monomer conversion reached 34.2 % (DP* = 34, A / n,* = 3.8k, L% = 96.8 %). The polymer was isolated by precipitation into methanol and then dried in vacuum oven (2.256 g, 22 % yield). Conventional SEC analysis (dRI, THF) reveals Mn= 3.9k, D = 1.13 (PSty calibration).

[0190]

[0123] Preparation of PPEGA-TTC (an exemplary first polymer)

[0191]

[0124] TTC1 (127 mg, 0.53 mmol) was charged into a 20 ml scintillation vial, followed by Polyethylene methyl ether acrylate (PEGA, Mn= 460) (5 g, 0.011 mol) and 6.065 ml dioxane ([PEGA]o = IM). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing the reaction mixture in a blue light ( = 458 nm) photoreactor for 2 hours. The integration of vinyl protons at 5.86 ppm were measured relative to CH2 next pendent ester group of the polymeric and monomeric side chains between 4.05 ppm to 4.38 ppm to determine monomer conversion. After 2 hours the monomer conversion reached 87 % (DP* = 17.4, fn,* = 8.2k). The polymer was isolated by precipitating into 4 : 1 / diethyl ether : hexane mixture twice and then dried in vacuum oven (3.74 g, 73% yield). Conventional SEC analysis (dRI, THF) reveals Ma= 8.4k, D = 1.16 (PSty calibration).

[0192]

[0125] Preparation of PNAM-TTC (an exemplary first polymer)

[0193]

[0126] Initiator AIBN (2.91 mg, 0.018 mmol) and TTC1 (127 mg, 0.708 mmol) was charged into a 20 ml scintillation vial, followed by 4-Acryloylmorpholine (NAM) (5 g, 0.035 mol) and 7.442 ml dioxane ([NAM]o = 3M). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing the reaction mixture in a heat block set to 70 °C for 2 hours. The integration of vinyl protons at 5.70 ppm were measured relative to CH3 of the Z-group at 0.92 ppm to determine monomer conversion. After 2 hours the monomer conversion reached 99 % (DPth = 50, A / n,th = 7.3k). The polymer was isolated by precipitating into diethyl ether twice and then dried in vacuum oven (4.5 g, 90% yield). Conventional SEC analysis (dRI, THF) reveals Mn= 2.8k, D = 1.20 (PSty calibration).

[0194] General procedure for RAFT metathesis

[0195]

[0127] Model CTA experiments were carried as follows in the example procedure:

[0196]

[0128] TTC1 (252 mg, 0.792 mmol) and XAN1 (194 mg, 0.792 mmol) were charged into a 3.7 ml scintillation vial equipped with stirrer bar, followed by 1.58 ml dioxane ([Total CTA]o = IM). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing next to UV lamp (X = 365 nm) for 104 hours. Samples were

[0197] taken under argon for 'H-NMR analysis. In all cases, Z-group CH2 next to trithiocarb onate was used to determine partial molar fraction.

[0198]

[0129] Exemplary RAFT Metathesis (reaction of an exemplary second CTA with an exemplary first polymer to form an exemplary second polymer)

[0199]

[0130] 2.7 grams of Polystyrene (A7n,th = 4.9k, 0.55 mmol) prepared by RAFT polymerization and 1.17 grams of CTA-XB1 (5.5mmol, 10 eq) was charged into 20 ml scintillation vial equipped with stirrer, to which 6 ml of dioxane was added to target total CTA concentration of approximately 1 Molar. The mixture was sealed and allowed to stirrer. After complete dissolution of the polymer, the solution was purged with argon for

[0200] 10 minutes. The RAFT interchange reaction was then carried out under UV (365 nm) light for 18 hours. The completion of the reaction can be assessed by in-situ 1H-NMR analysis from disappearance of proton signal with chemical shift of 3.3 ppm that corresponds to CH2 signal next to the trithiocarb onate of the original polymer. Once completed, the polymer was isolated by precipitation into hexanes and collected by centrifugation. The precipitated polymer was then redissolved in chloroform and precipitated into hexane 2 additional times to remove excess Xan Bl, resulting in a yield of 2.25 grams (83 %).

[0201]

[0131] RAFT Metathesis with PSty-TTC (reaction of an exemplary second CTA with an exemplary first polymer to form an exemplary second polymer)

[0202]

[0132] PSty-TTC (200 mg, 0.053 mmol) and XAN1 (102 mg, 0.526 mmol) were charged into a 3.7 ml scintillation vial equipped with stirrer bar, followed by 0.578 ml dioxane ([Total CTA]o = IM). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing next to UV lamp ( = 365 nm) for 16 hours. The polymer then precipitated into methanol three times to remove excess CTA and dried in vacuum (121 mg, 61 % yield). The end group was characterized by 'H-NMR analysis (CDCI3). The fraction of “unmodified” PSty-TTC was quantified by integrating peak at 3.21 ppm - 3.36 ppm corresponding to CH2 next to the trithiocarb onate on the Z-group. The fraction of PSty-XAN was quantified from integrating an overlapping peak at 4.19 ppm - 4.57 ppm corresponding to CH on the terminal monomer unit next to the Xanthate and CH 2 next to the Xanthate on the Z -group.

[0203]

[0133] RAFT metathesis with PPEGA-TTC (reaction of an exemplary second CTA with an exemplary first polymer to form an exemplary second polymer)

[0204]

[0134] PPEGA-TTC (534 mg, 0.053 mmol) and XANB1 (212 mg, 0.526 mmol) were charged into a 3.7 ml scintillation vial equipped with stirrer bar, followed by 0.682 ml dioxane ([Total CTA]o = IM). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing next to UV lamp ( = 365 nm) for 16 hours. The polymer then precipitated into 4 : 1 / diethyl ether : hexane mixture three times to remove excess CTA and dried in vacuum (140 mg, 70 % yield). The end group was characterized by 'H-NMR analysis (CDCh). The fraction of “unmodified” PPEGA-TTC was quantified by integrating peak at 4.75 ppm - 4.90 ppm corresponding to CH on the terminal monomer unit next to the trithiocarb onate. The fraction of PPEGA-XAN was quantified from integrating an overlapping peak at 4.57 ppm - 4.62 ppm corresponding to CH on the terminal monomer unit next to the Xanthate and CH next to the Xanthate on the Z -group.

[0205]

[0135] RAFT metathesis with PMMA-TTC

[0206]

[0136] PMMA-TTC (200 mg, 0.0488 mmol) and XANB2 (110 mg, 0.488 mmol) were charged into a 3.7 ml scintillation vial equipped with stirrer bar, followed by 0.537 ml dioxane ([Total CTA]o = IM). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing next to UV lamp ( = 365 nm) for 16 hours. The polymer then precipitated into hexane mixture three times to remove excess CTA and dried in vacuum (150 mg, 75 % yield). The end group was characterized by 'H-NMR analysis (CDCI3). Complete disappearance of peak at 3.19 ppm - 3.26 ppm corresponding to CH2 next to the trithiocarb onate on the Z-group was observed. Additionally, no peaks corresponding to the Xanthate end-group was observed (expected region: 4.57 ppm - 4.62 ppm for CH 2 next to the Xanthate on the Z -group).

[0207]

[0137] RAFT metathesis with PNAM-TTC (reaction of an exemplary second CTA with an exemplary first polymer to form a second polymer)

[0208]

[0138] PNAM-TTC (3.670 g, 0.508 mmol) and XANB1 (1077 mg, 5.079 mmol) were charged into a 20 ml scintillation vial equipped with stirrer bar, followed by 5.587 ml dioxane ([Total CTA]o = IM). The vial was then secured by a rubber septum and stirred until complete dissolution of the polymer. The mixture was purged with argon for 10 minutes, prior to placing next to UV lamp (X = 365 nm) for 16 hours. The polymer then precipitated into diethyl ether three times to remove excess CTA and dried in vacuum (3.0 g, 82 % yield). The end group was characterized by 'H-NMR analysis (CDCh). Complete disappearance of peak at 5.10 ppm - 5.26 ppm corresponding to CH on the terminal monomer unit next to the trithiocarb onate of PNAM-TTC was observed. End- group of PNAM-XAN is evident from the overlapping peaks at 4.58 ppm - 4.77 ppm corresponding to CH on the terminal monomer unit next to the Xanthate and CH2 next to the Xanthate on the Z -group.

[0209] Block copolymerization (reaction of an exemplary second polymer with an exemplary LAM to form an exemplary block copolymer of Formula P-1)

[0210]

[0139] PPEGA-XAN ( fn,th = 8.6k)(320 mg, 0.0371 mmol) was charged into a 3.7 mL scintillation vial, followed by vinyl butyrate (VB) (750 mg, 6.571 mmol). Next 0.440 mL dioxane and then 54 pL of AIBN stock solution (20 mg / mL in dioxane) (6.6 pmol, [AIBN]o = 5 mM). The vial was then secured by a rubber septum and purged with argon for 10 minutes, prior to placing the reaction mixture in a heat block set to 75 °C for 4 hours. The integration of vinyl protons at 4.53 ppm were measured relative to CH3 of VB side chains at 0.97 ppm to determine monomer conversion. After 4 hours the monomer conversion reached 31 % (PVB DPth = 54, block copolymer Ma, th = 14.8k). Conventional SEC analysis (dRI, THF) reveals Mn= 13.1k, D = 1.30 (PSty calibration).

[0211]

[0140] Efforts have been made to ensure accuracy with respect to numbers used (e.g. amounts, temperature, etc.) but some experimental errors and deviations should be accounted for.

[0212]

[0141] One skilled in the art will recognize many methods and materials similar or equivalent to those described herein, which could be used in the practicing the subject matter described herein. The present disclosure is in no way limited to just the methods and materials described.

[0213]

[0142] Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter belongs, and are generally consistent with the Compendium of Chemical Terminology, IUP AC Recommendations, 2ndEd. 2019, available at https: / / goldbook.iupac.org.

[0214]

[0143] Throughout this specification and the claims, the words “comprise,” “comprises,” and “comprising” are used in a non-exclusive sense, except where the context requires otherwise. It is understood that embodiments described herein include “consisting of’ and / or “consisting essentially of’ embodiments.

[0215]

[0144] As used herein, “and / or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”).

[0216]

[0145] The term “about” as used herein when referring to a measurable value, such as, for example, an amount or concentration and the like, is meant to encompass variations of 20%, ± 10%, ± 5%, ± 1%, ± 0.5%, or even ± 0.1% of the specified amount. A range provided herein for a measurable value may include any other range and / or individual value therein.

[0217]

[0146] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit, unless the context clearly dictates otherwise, between the upper and lower limit of the range and any other stated or intervening value in that stated range, is encompassed. The upper and lower limits of these small ranges which may independently be included in the smaller rangers is also encompassed, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included.

[0218]

[0147] Many modifications and other embodiments set forth herein will come to mind to one skilled in the art to which this subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

THAT WHICH IS CLAIMED:

1. A RAFT polymerization process for preparing a block copolymer, comprising forming a first polymer by allowing a plurality of first monomers (Ml) to react with a first CTA comprising a R1 group and a Z1 group to form the first polymer comprising residues of Ml and the R1 and Z1 groups; forming a second polymer by allowing the first polymer to react with a second CTA comprising a R2 group and a Z2 group to form the second polymer comprising the residues of Ml and the R1 and Z2 groups; forming a block copolymer by allowing a plurality of second monomers (M2) to react with the second polymer to form the block copolymer, wherein the block copolymer comprises Ml -M2 blocks and R1 and Z2.

2. The RAFT polymerization process of claim 1, wherein R1 R2; Z1 Z2; R1Z1 or Z2; R2 ^ Zl or Z2.

3. The RAFT polymerization process of claim 1, wherein the process yields predominantly uniform Ml -M2 blocks.

4. The RAFT polymerization process of claim 1, wherein the process yields predominantly uniform (Ml)m-(M2)nblocks, wherein m is an integer from 2 to 1,000; or from 2 to 500; or from 2 to 200; or from 2 to 100; or from 2 to 50; or from 2 to 40; or from 2 to 30; or from 2 to 20; or from 2 to 10; or from 2 to 5; and n is an integer from 2 to 1,000; or from 2 to 500; or from 2 to 200; or from 2 to 100; or from 2 to 50; or from 2 to 40; or from 2 to 30; or from 2 to 20; or from 2 to 10; or from 2 to 5.

5. The RAFT polymerization process of claim 1, wherein the first CTA has a structure of Formula I:

6. The RAFT polymerization process of claim 1, wherein R1 is selected from the group consisting of:wherein, * indicates attachment of the R1 to the -S atom; and,X, Y and Z are each independently selected from the group consisting of alkyl, H, cyano, halogen, alkene, alkyne, ester, carboxylic acid, (primary, secondary, tertiary) amides, aryl and heteroaryl.

7. The RAFT polymerization process of claim 1, wherein Z1 is selected from the group consisting of aryl, -S-alkyl and heteroaryl.

8. The RAFT polymerization process of claim 7, wherein Z1 is selected from the group consisting of phenyl, -S-(Ci-6 alkyl) and pyrrolyl.

9. The RAFT polymerization process of claim 1, wherein the second CTA has a structure of Formula II:

10. The RAFT polymerization process of claim 1, wherein R2 is selected from the group consisting of :wherein, * indicates attachment of the R2 to the S atom; and,X, Y and Z are each independently selected from the group consisting of alkyl, H, cyano, halogen, alkene, alkyne, ester, carboxylic acid, (primary, secondary, tertiary) amides, aryl and heteroaryl.

11. The RAFT polymerization process of claim 1, wherein Z2 is selected from the group consisting of -O-aryl; O-alkyl and -dialkylamines.

12. The RAFT polymerization process of claim 11, wherein Z2 is selected from the group consisting of -O-aryl; O-alkyl and -dialkylamines.

13. The RAFT polymerization process of claim 12, wherein Z2 is selected from the group consisting of -O-phenyl; O-(Ci-6 alkyl) and -N-diethyl.

14. The RAFT polymerization process of claim 1, wherein Ml is a MAM.

15. The RAFT polymerization process of claim 14, wherein the MAM is selected from the group consisting of butadiene, isoprene, styrene, vinyl pyridine, (meth)acrylates, (meth)acrylamides, maleic anhydride, maleimide, and acrylonitrile.

16. The RAFT polymerization process of claim 1, wherein M2 is a LAM.

17. The RAFT polymerization process of claim 16, wherein the LAM is selected from the group consisting of vinyl acetate, N-vinylpyrrolidone (NVP), vinyl chloride, and alkenes.

18. The RAFT polymerization process of claim 1, wherein the forming a polymer or block copolymer is performed in a solvent in the presence of an initiator and heat.

19. The RAFT polymerization process of claim 1, further comprising cleaving a terminal end of the polymer or block copolymer.

20. A block copolymer having a structure of Formula P-1 :wherein, Rl, Ml, n, M2 and Z2 are as described herein.

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