Microplastic Removal Using Adhesives

Abstract

The present invention discloses articles comprising a pressure-sensitive adhesive and methods for their use in removing microplastic and nanoplastic particles from various media, including wastewater effluents, laundry wash effluents, and indoor air.

Description

Background Art

[0001] Microplastics have been found in locations as far afield as the Arctic (Bergmann et al., 2019) and the deepest parts of the ocean (Peng et al., 2018), as well as in our food (Cox et al., 2019) and drinking water. (Novotna et al., 2019) The environmental persistence of microplastics is due to the same properties that make plastics desirable (e.g., their inertness and durability). Despite efforts to remove large plastic items from the environment, guided by regulations, takebacks, and scientific and engineering advances, relatively little has been done to address microplastic pollution. Although recent legislation has banned the intentional addition of microplastics to certain products (e.g., facial scrubs and abrasives), the contribution of such products to microplastic pollution is actually quite small. (McDevitt et al., 2017)

[0002] Microplastics are generated from many sources, including the physical degradation of existing plastic items in the environment. However, one of the largest contributors to microplastic pollution is the washing of textiles. (Belzagui et al., 2019; Yang et al., 2019) Microfibers of polyester, polyamide, and polyacrylate are released into so-called "gray water" during the clothing washing cycle, which is sent to wastewater treatment plants (WWTPs) and / or directly released into the environment. (Hernandez et al., 2017) For example, polyester clothing can generate over 1,900 microfibers per wash per meter 2 , while acetate-based clothing can release approximately 75,000 microfibers per wash per meter 2 . (Yang et al., 2019) There are approximately 840 million household washing machines globally, generating a total of approximately 20 km 3 of wastewater contaminated with microfibers each year. In most locations in the United States, this clothing washing effluent is sent to WWTPs. Recent studies have shown that U.S. wastewater treatment facilities are 90%–98% effective in reducing microplastic pollution in water. (Xu et al., 2018)

[0003] Based on screens and filters, wastewater treatment processes are surprisingly effective at removing large plastic particles (Peller et al., 2019) and microplastics that co-precipitate with other organic matter in the sludge. (Lo et al., 2019; Bayo et al., 2020) However, even with this significant reduction, WWTP facilities in the United States still release (on average) over 4 million particles per day per facility. (Mason et al., 2016) However, smaller suspended microplastics and nanoplastics are not removed and are released into the watershed. A recent review of over 100 articles found that effluents and biosolids from wastewater treatment plants constitute the largest contributor of microplastics to the environment. (Wong et al., 2020) Additionally, the vast majority of microplastics captured by WWTPs are co-located in nutrient-rich sludge, which is incinerated, landfilled, or most commonly sold for agricultural use.( Figure 1 , Peller et al., 2019) The reuse of this sludge creates an endless cycle of environmental pollution, where previously captured microplastics re-enter the watershed and, in many cases, the food chain again. SUMMARY OF THE INVENTION

[0004] In some aspects, the subject matter disclosed herein provides a method for removing microplastic or nanoplastic particles from a medium, the method comprising contacting the microplastic or nanoplastic particles in the medium with an article comprising one or more pressure-sensitive adhesives, wherein the one or more pressure-sensitive adhesives comprise a compound of formula (I) or formula (II):

[0005]

[0006] Wherein:

[0007] Each n is independently an integer from 1 to 10,000;

[0008] Each R1, R2, and R3, if present, is independently selected from the group consisting of:

[0009]

[0010] Wherein: each m is independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8; p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8; u is an integer selected from the group consisting of 1, 2, 3, 4, and 5; v is an integer selected from the group consisting of 1, 2, 3, and 4; w is an integer selected from the group consisting of 1, 2, and 3; each R4 is independently selected from the group consisting of: H, C1-C8 substituted or unsubstituted branched or straight-chain alkyl, hydroxy, C1-C8 alkoxy, amino, cyano, -CF3, carbonyl, carboxyl, C1-C8 alkynyl, acyl, carbamoyl, halogen, nitro, mercapto, and thiol; and R5 is C3-C 20 branched alkyl.

[0011] In some aspects, R1, R2, and R3, if present, are each independently selected from the group consisting of:

[0012]

[0013] Wherein p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8.

[0014] In some aspects, the pressure-sensitive adhesive is made from recycled superabsorbent polymer (SAP). In certain aspects, the recycled SAP is degraded to poly(acrylic acid) (PAA); and wherein the PAA is derivatized to a pressure-sensitive adhesive.

[0015] In certain aspects, the microplastic or nanoplastic particles comprise a material selected from the group consisting of: rubber, poly(isoprene), polyamide, polyester, poly(ethylene), poly(propylene), polystyrene, nylon, cellulose, poly(ethylene terephthalate), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), poly(tetrafluoroethylene) (PTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), perfluoroelastomer (FFPM / FFKM), chlorotrifluoroethylene - vinylidene fluoride (FPM / FKM), tetrafluoroethylene - propylene (FEPM), perfluoropolyether (PFPE), perfluorosulfonic acid (PFSA), perfluoropolyepoxybutane, and combinations thereof.

[0016] In some aspects, the medium is selected from the group consisting of an aqueous medium and an atmospheric medium. In more certain aspects, the aqueous medium is selected from the group consisting of: wastewater effluent from a wastewater treatment plant, laundry effluent from a commercial laundry facility, laundry effluent from a personal washing machine, and fill water in a washing machine during or after a wash cycle.

[0017] In some aspects, the atmospheric environment is selected from the group consisting of: indoor air, outdoor air, and emissions, exhaust gases, and / or exhaust from commercial or personal dryers.

[0018] In other aspects, the method further includes removing microplastic or nanoplastic particles from one or more pressure - sensitive adhesives.

[0019] In some aspects, the subject matter disclosed herein provides an article comprising one or more pressure - sensitive adhesives, wherein the one or more pressure - sensitive adhesives comprise a compound of formula (I) or formula (II):

[0020]

[0021] Wherein:

[0022] Each n is independently an integer from 1 to 10,000;

[0023] Each R1, R2, and R3, if present, is independently selected from the group consisting of:

[0024]

[0025] Wherein: each m is independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8; p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8; u is an integer selected from the group consisting of 1, 2, 3, 4, and 5; v is an integer selected from the group consisting of 1, 2, 3, and 4; w is an integer selected from the group consisting of 1, 2, and 3; each R4 is independently selected from the group consisting of: H, C1 - C8 substituted or unsubstituted branched or straight - chain alkyl, hydroxy, C1 - C8 alkoxy, amino, cyano, - CF3, carbonyl, carboxyl, C1 - C8 alkynyl, acyl, carbamoyl, halogen, nitro, mercapto, and thiol; and R5 is C3 - C 20 branched alkyl.

[0026] In certain aspects, R1, R2, and R3 are each independently selected from the group consisting of:

[0027]

[0028]

[0029] Wherein p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8.

[0030] In some aspects, the article comprises a pressure - sensitive adhesive made from recycled superabsorbent polymer (SAP). In certain aspects, the recycled SAP degrades to poly(acrylic acid) (PAA); and wherein the PAA is derivatized to a pressure - sensitive adhesive.

[0031] In certain aspects, the article includes a solid shape selected from the group consisting of a rod, a brush, a sphere, an impeller, a rectangular slider, an oblate spheroid, a cube, a pyramid, a hexagon, an octagon, and combinations thereof, wherein the solid shape can be closed or open. In a more specific aspect, the shape further includes protruding filaments coated with one or more pressure - sensitive filaments.

[0032] In additional aspects, the article is included in an air - circulation system or device.

[0033] In yet additional aspects, the subject matter disclosed herein provides a washing machine or dryer that includes the article disclosed herein.

[0034] In other aspects, the subject matter disclosed herein provides a kit that includes the article disclosed herein.

[0035] Certain aspects of the subject matter disclosed herein have been set forth above, which are, in whole or in part, solved by the subject matter disclosed herein, and other aspects will become apparent as the description proceeds when taken in conjunction with the appended examples and drawings as best described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The patent or application file includes at least one color - drawn picture. A copy of this patent or patent - application publication with color pictures will be provided by the patent office upon request and payment of the necessary fees.

[0037] Thus, the subject matter disclosed herein has been described in general terms, and now reference will be made to the drawings, which are not necessarily drawn to scale, and in which:

[0038] Figure 1 Shows the fate of microplastics in the Lake Michigan watershed. (MF = microfiber; image taken from Peller et al., 2019 (prior art));

[0039] Figure 2 Shows the conventional synthesis of a pressure - sensitive adhesive using petroleum - sourced monomers (top, red) versus using recycled superabsorbent polymer fragments (bottom, blue);

[0040] Figure 3 Shows the M w and w max of sonicated PAA at 5% w / v as a function of time (left) and the IR spectrum of esterification with 3 - 5 equivalents of 2 - ethylhexanol (right);

[0041] Figure 4 Shows PAA shortened by esterification chain SAP The viscoelastic window spanned by the synthesized PSA;

[0042] Figure 5 Shows poly(ethylene) (PE) microplastics captured on a glass slide coated with the pressure-sensitive adhesive disclosed in the present invention;

[0043] Figure 6 To demonstrate the use of the adhesive made from recycled PAA SAP Schematic diagram of the use of the adhesive for capturing microplastics in water;

[0044] Figure 7 Shows a representative adhesive structure synthesized from waste diapers, etc.;

[0045] Figure 8 Shows an optical micrograph demonstrating that a poly(2-ethylhexyl acetate) pressure-sensitive adhesive captures polyethylene and poly(isoprene), but not poly(ethylene terephthalate);

[0046] Figure 9 Shows an optical micrograph of a glass microscope slide coated with the pressure-sensitive adhesive (PSA) disclosed in the present invention, which demonstrates the ability of the PSA to capture microplastics in an aqueous solution in the presence of laundry detergent at an actual detergent concentration. The image of the slide was taken after removal from the solution, and then the water was allowed to evaporate (about 30 min). The slide was immersed in the solution and shaken for about 10 seconds to about 20 seconds to allow microplastic / adhesive contact, and then it was removed and air-dried. In this example, the slide coated with the PSA disclosed in the present invention effectively removed as much microplastic as the control (no detergent) at lower detergent levels;

[0047] Figure 10 Shows a representative three-dimensional article having protruding adhesive filaments coated with the pressure-sensitive adhesive disclosed in the present invention;

[0048] Figure 11 a, Figure 11 b and Figure 11 c show preliminary experiments demonstrating the use of an adhesive-coated stir bar to capture micronized rubber (~100 μm) suspended in water to remove microplastics from water ( Figure 11 a), and the ImageJ calculation of the percentage of the area covered by 20-μm nylon ( Figure 11 b) and 300-μm PET ( Figure 11 c) captured by an adhesive-coated glass slide at different initial microplastic concentrations;

[0049] Figure 12o, Figure 12 a, Figure 12 b, Figure 12 c and Figure 12 d show preliminary experiments studying spherical beads as substrates for microplastic removal. Figure 12 o) A sieve coated with an adhesive that initially aggregates before the MP capture experiment and decomposes after the experiment. Figure 12 a) SEM image of the sieve after capturing 300-μm PET in water. Figure 12 b) Magnified SEM image of the sieve after capturing 300-μm PET in water. Figure 12 c) SEM image of the sieve after capturing 90-μm PS in water. Figure 12 d) Magnified SEM image of the sieve after capturing 90-μm PS in water;

[0050] Figure 13 Show optical micrographs of 90-μm PS captured by 0.5-mm beads coated with PAA SPP-950k at different time points (left, 0.5 min; middle, 1 min; right, 2 min);

[0051] Figure 14 a and Figure 14 b show: Figure 14 a) A diagram of the internal workings of a flow cytometer instrument. Figure 14 b) Dot plot scatter data of the experimental sample, showing the distribution of particle events in the aggregated state at the interrogation point;

[0052] Figure 15 a and Figure 15 b are graphs of how to analyze according to the detector Figure 15 a) A unimodal peak and Figure 15 b) A bimodal peak. The bimodal peak has the same height but double the area;

[0053] Figure 16 a and Figure 16 b are graphs for evaluating the PSA efficiency of removing 10-μm PS beads from water. Figure 16 a) Evaluating the removal percentage of all four tested adhesives over time. Figure 16 b) Showing the relative counts of potential adhesive stripping fragments, unimodal peaks, bimodal peaks, and triplet peaks (not visible on the graph) of P(2-EHA) Sigma-92k and P(2-EHA) P&G-450k ;

[0054] Figure 17 Show the visualization of a 2-mm molecular sieve before (left) and after (right) microplastic removal after the use of the coated adhesive;

[0055] Figure 18 a, Figure 18 b, and Figure 18 c are SEM images of 2-mm used molecular sieves after capturing 300-μm PET in water;

[0056] Figure 19 a, Figure 19 b, and Figure 19 c are SEM images of 2-mm used molecular sieves after capturing 90-μm PS in water;

[0057] Figure 20 Optical microscope images of 90-μm PS captured by 0.5-mm beads coated with PAA SPP-950k are shown (left figure, 0.5 min; middle figure, 1 min; right figure, 2 min);

[0058] Figure 21 a, and Figure 21 b show the effect of surfactant (sodium dodecyl sulfate) concentration on the removal of MP (40-μm PS). Figure 21 a) Optical microscopic images of MP removal at various SDS concentrations are shown. Figure 21 b) Bar graphs showing the percentage coverage calculated using ImageJ software are shown;

[0059] Figure 22 is a photograph of a glass slide coated with P(2-EHA) P&G_780k for MP removal; and

[0060] Figure 23 Optical microscopic images showing the effect of surfactant on microplastic removal are shown. Detailed Description of the Invention

[0061] The subject matter disclosed herein will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the subject matter disclosed are shown. Like numerals refer to like elements throughout. The subject matter disclosed can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the subject matter disclosed herein will come to mind to those skilled in the art having the benefit of the teachings presented in the foregoing description and the related drawings. Therefore, it is to be understood that the subject matter disclosed herein is not limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.

[0062] I. Microplastic Removal Using Adhesives

[0063] Synthetic polymers used in most consumer applications are essential for our daily lives; however, their current sustainability characteristics need improvement. More than 90% of the raw materials used to obtain these polymers come from non-renewable petroleum resources. (Geyer et al., 2017) Unfortunately, the chemical structures that are expected to confer high performance and durability (e.g., a tough carbon-carbon backbone) also result in the persistence of post-consumer polymers in the environment. (Barnes et al., 2009; Hong and Chen, 2017)

[0064] The method disclosed in the present invention includes capping common plastic waste – for example, superabsorbent polymers (SAPs) used in baby diapers, adult incontinence products, and feminine hygiene products. It is estimated that the global annual production of this PAA SAP (i.e., sodium polyacrylate) exceeds 2 million metric tons, and disposable diapers account for 74% of the global market. (Future Market Insights. SuperAbsorbent Polymer Market: Global Industry Analysis and Opportunity Assessment 2015–2020) If not incinerated, PAA SAP remains in landfills for centuries without degrading. (Barnes et al., 2009)

[0065] To this end, methods for the reuse of post-consumer SAP have been previously developed. See, for example, U.S. Provisional Patent Application 62 / 890,880, filed August 23, 2019, and entitled Depolymerization of Polymers, to Collias, D.I., Zimmerman, P.M., Chazovachii, P.T., Robo, M.T., and McNeil, A.J.; U.S. Patent Application Publication 20210054161, published February 25, 2021, and entitled Depolymerization of Polymers, to Collias et al.; U.S. Provisional Patent Application 62 / 947,363, filed December 12, 2019, and entitled Esterifying Polyacrylic Acid with High Conversion, to McNeil, A.J., Chazovachii, P.T., Robo, M.T., Marsh, N.G., Zimmerman, P.M., James, M.I., and Collias, D.I.; and U.S. Provisional Patent Application 62 / 890,943, filed August 23, 2019, and entitled Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives, to Collias, D.I., Zimmerman, P., Chazovachii, P.T., Robo, M.T., and McNeil, A.J.; WO2021041326, published March 4, 2021, and entitled Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives, to Collias et al., and U.S. Patent Application Publication 20210054248, published August 24, 2020, and entitled Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives, to Collias et al., each of which is incorporated herein by reference in its entirety. In certain embodiments, the SAP described herein is an insoluble crosslinked network polymer with an absorbency capacity of about 50 g / g of 0.9% NaCl (aqueous solution).

[0066] In this process, the items used are first collected and sterilized, body fluids and contaminants are removed, and the components are separated using a semi-commercial Fater method. (EP 2596811 (B1) granted to Somma et al., Apparatus and Process for Sterilising Absorbent Sanitary Products, 2014; EP 2596810 (A1), Sterilisation of Used Absorbent Sanitary Products. EP 2596810 (A1) granted to Somma et al., 2013; https: / / www.fatersmart.com; Arena et al., 2016) The process includes a method of dehydrating superabsorbent polymers using liquid phase extraction with dimethyl ether; and a synthetic method of reusing SAP as a value-added material (i.e., pressure-sensitive adhesive (PSA)) using structural property insights collected from computational data and analysis. The value of the method is illustrated by simulating the social and environmental life cycle of this chemical recycling method, which finds that the global warming potential, fossil energy consumption, and human health impacts are significantly reduced, with increased economic value compared to existing technology recycling techniques for SAP.

[0067] PSA is the fastest-growing class of adhesives, with a variety of applications including tapes, packaging, labels, sticky notes, bandages, and cling film. (Creton, 2003) Most commercial PSAs are obtained via air-sensitive free radical polymerization of acrylic monomers that rely on petroleum sources ( Figure 2 , top). See, for example, U.S. Patent 9,822,286 to Fornof et al. for Self-Wetting Adhesive Composition, published November 21, 2017; Pocious, 2002; O’Connor and Willenbacher, 2004; European Basic Acrylate Manufacturers, 2018.

[0068] Obtaining acrylic structural units solely from petroleum consumes approximately 50 MJ / kg of specific energy (w). An alternative method was developed in which PAA SAP is de-crosslinked via hydrolysis, the chains are shortened to structural units via sonication, and functionalized to PSA via esterification ( Figure 2 , bottom). In this alternative method, the initial goal was to obtain chain-shortened PAA with an appropriate weight-average molecular weight (M w ) at w < 50 MJ / kg SAPStructural unit. A second goal is to develop a relatively inexpensive method to esterify poly(acrylic acid) with a high conversion rate.

[0069] The efficiency of chain shortening can be optimized by adjusting multiple variables (i.e., de-crosslinking, sonication time, and concentration) to achieve appropriately sized fragments below the maximum specific energy consumption limit (w max <50 MJ / kg). Fragments as short as approximately 300 kg / mol were found to be obtainable below the w max limit ( Figure 3 , left).

[0070] Since acrylic PSA has a relatively high entanglement molecular weight (M e ), the goal is that M w fragments of ≥ 400 kg / mol are given sufficient cohesive strength without crosslinking. (Tobing and Klein, 2001) For the functionalization step, Fischer esterification was chosen because it is considered relatively easy and inexpensive for industrial applications. However, Fischer esterification yields low due to the equilibrium with ester hydrolysis, and various strategies are usually employed, such as selective removal of water or using a large excess of alcohol. (U.S. Patent 2,917,538 to Carlyle, entitled Production of Acrylic Acid Esters, published December 15, 1959)

[0071] Interestingly, it was found that complete esterification could be achieved regardless of the alcohol concentration (3 - 15 equivalents of 2-ethylhexanol) ( Figure 3 , right). Further experiments and calculations (not detailed herein) showed that the hydrophobic reaction environment (i.e., immiscibility of 2-ethylhexanol and water) led to water exclusion, which thus hindered hydrolysis. The adhesion performance of the synthesized PSA was evaluated using Chang’s viscoelastic window (VW) concept. (Chang, 1991) The PSA fell into quadrant 3 and the central region of the VW ( Figure 4 ), which includes various removable PSA applications (e.g., office tapes, sticky notes, bandages, removable labels, etc.).

[0072] Unexpectedly, it was found that the PSA prepared by this method was also significantly effective in capturing microplastics dispersed in aqueous solutions. In an illustrative example, rubber, polyamide, polyester, polyethylene, and polystyrene microplastics of different sizes and shapes were adsorbed on a thin PSA coating on a glass slide. See, for example Figure 5 . Thus, PSA previously developed from waste diapers, etc. can be reused to remove microplastics from various media including water. See, for example Figure 6It is contemplated that the technology disclosed in the present invention can be applied to large-scale, high-impact applications for removing microplastics from wastewater at a WWTP and subsequent reuse of these microplastics, as well as for smaller devices or articles for capturing microfibers at their source (e.g., laundry wash effluent) before they are transported to a water source (e.g., sewer), or as a sedimentation or flotation aid in wastewater.

[0073] Microplastics are plastic particles smaller than about 5 mm in size. These particles are intentionally introduced into the environment as additives in consumer products (major source) or through physical degradation of existing plastic materials (minor source). Most microplastic pollution in the environment has been traced back to the washing of textiles, where more than 20 km 3 of water contaminated with microplastics is generated globally each year, (De Falco et al., 2019) and is treated in wastewater treatment plants. (Hernandez et al., 2017) During the treatment process, most of the microplastics (90%-98%) in the influent are only captured with the biosolids and reintroduced into the environment as organic fertilizer. See Figure 1 (Peller et al., 2019).

[0074] Existing methods for removing microplastics from water involve physical interception in filters (laboratory scale) or in sludge formation (WWTP). In both cases, only larger microplastics are captured, and smaller / thinner microplastics, including nanoplastics that are more dangerous to humans and wildlife, easily pass through. The subject matter disclosed in the present invention provides an alternative method to overcome this limitation by capturing microplastics using non-covalent interactions. Thus, it is expected to capture large and small / thin microplastics (including nanoplastics). It is believed that the pressure-sensitive adhesives disclosed in the present invention will exhibit high adsorption efficiency for microplastics of different compositions, sizes, and shapes. Without wishing to be bound by any particular theory, it is believed that the efficacy of the method of the present invention will depend on the effect of the chemical structure of the adhesive on the adhesiveness to microplastics and the composition / size / shape of the microplastics.

[0075] There are several commercial laundry products for reducing microfibers at the machine level: (i) The Lint LUV–R uses a stainless-steel mesh to capture large microfibers. http: / / www.environmentalenhancements.com; (ii) The CORA ball uses multiple small round holes to capture large microfibers. https: / / coraball.com; (iii) The GuppyFriend nylon mesh bag operates under a similar physical capture principle. https: / / guppyfriend.com. Only the first two of these products have been tested in peer-reviewed scientific studies, with the Lint LUV–R being the most effective (reducing 87%) (versus the CORA ball (reducing 25%)). (McIlwraith et al., 2019) All three methods use physical interception to remove larger microfibers from laundry effluents.

[0076] The subject matter disclosed in the present invention represents a paradigmatic removal method that relies on particle interception via adhesion. The advantage of this method is that the adhesion properties can be tuned to optimally capture microplastics based on their composition and there is no angular dependence when the microplastics encounter the “filter”.

[0077] Unlike existing methods that rely on physical interception (e.g., the CORA ball (https: / / coraball.com), GuppyFriend (https: / / guppyfriend.com), etc.), the technology disclosed in the present invention is based on non-covalent chemical interactions. Thus, the PSA can capture microplastics well below the conventional threshold (about 50 μm to about 100 μm). In addition to the 2-ethylhexyl functional group used to prepare these adhesives, other functional groups that can enhance the underwater adhesive / microplastic interaction are also suitable for use with the subject matter disclosed in the present invention. (Waite, 1983; Tiu et al., 2019; and Clancy et al., 2016)

[0078] Good underwater adhesion is achieved by tuning the pressure-sensitive adhesive to have surface energy components (γ = γ d +γ h ) compatible with the target microplastics. In other words, the adhesive is designed to exhibit a polar component (γ h ) and a dispersive component (γ d) ratio. More specifically, adhesives with dispersive components (e.g., 2-ethylhexyl, stearyl, fluoroalkyl, etc.) will effectively capture similar dispersed microplastics (e.g., poly(ethylene)). Similarly, adhesives containing groups with similar highly polar components (e.g., aromatic, ionic, Lewis base / acid, etc.) can be used to capture microplastics with highly polar components (e.g., nylon, cellulose, poly(ethylene terephthalate), etc.). Such adhesive modifications are informed by mimicking marine adhesives and principles relating surface energy parameters to adhesion. (Agirre et al., 2010; Kenney et al., 1992; and Karnal et al., 2019)

[0079] Several different types of adhesives can potentially be used to remove microplastics of different sizes, shapes, and compositions. Microplastics and PSAs have different properties, and understanding the relationship between their structure and adhesion ability will yield an adjustable platform for effectively capturing microplastics. Regarding adhesive structure, pressure-sensitive adhesives exhibit both viscous (flow) and elastic (resistance) properties. (Creton, 2003) As the name implies, an adhesive “bond” is formed between two materials with gentle pressure. For strong adhesion, the adhesive must come into close contact with the surface during a process called wetting. The degree of wetting depends on the chemical composition of that surface.

[0080] One parameter used to predict wetting is surface energy, which is the excess energy generated at the surface due to the lack of stable interactions present in the bulk. Materials with high surface energy (e.g., metals and glass) readily form strong interactions with most adhesives (which have lower surface energy). As an illustrative example, an adhesive made from recycled diapers adheres readily to a glass slide ( Figure 5 ). On the other hand, plastics have lower surface energy and are more challenging to bond to. However, many adhesives have been developed to adhere to low-surface-energy plastics, including polyethylene. (Agirre et al., 2010) In fact, the synthetic adhesives disclosed in the present invention are shown to capture PE microplastics in an aqueous solution ( Figure 5 [[ID=ID=10]])).

[0081] Of further interest is elucidating how the chemical structure of an adhesive affects its efficiency in removing microplastics from water. Despite a large body of literature on adhesive / plastic interactions, much of this work was conducted in air and cannot be translated to aqueous systems. As evidence, reduced adhesion strength was found both in humid environments (Kenney et al., 1992) and in aqueous media when water was deliberately included. (Karnal et al., 2017; Tiu et al., 2019)

[0082] The surface energy of materials can be further decomposed into two components - polar contribution and dispersive contribution. Some microplastics have a solely dispersive surface energy (e.g., PE, PP) (Zhu et al., 2019), while other microplastics have some polar contribution (e.g., polyamide, PET). (Owens and Wendt, 1969) Although a single universal adhesive is more desirable from a usage perspective, having unique selective adhesives for specific microplastics may facilitate their ultimate separation and reuse. Two classes of adhesives are particularly suitable for the role of matching the polar / dispersive contribution of the adhesive to the microplastics to be captured.

[0083] One class of adhesives is based on the strong underwater adhesion exhibited by mussel and barnacle proteins. (Waite, 1983) These adhesion proteins display side chains with polar, ionic, and hydrophobic groups, indicating that all three are important for underwater adhesion to different surfaces. While most mussel protein mimics utilize the catechol moiety as the polar group, this functional group is actually avoided because it can undergo oxidation, which would lead to long-term degradation problems under realistic conditions.

[0084] Recently, Tiu et al., 2019 and Clancy et al., 2016 showed that adhesives with benzyl (as an alternative to catechol) match the adhesion strength in water of similar catechol-containing adhesives. (Clancy et al., 2016) Thus, in some embodiments, a previously developed general acid-catalyzed esterification method can be used to introduce different ratios of benzyl, alkyl, and ionic side chains ( Figure 7 , Scheme I). All of these adhesives can ultimately be synthesized starting from waste superabsorbent polymers. This method will produce copolymers with a random sequence of functional groups.

[0085] Other tunable variables include molecular weight (which can be adjusted by varying the sonication time) and molecular weight distribution (which can be adjusted by mixing different batches with different number-average or weight-average molecular weights). Previous studies have shown that, generally speaking, lower molecular weight and higher molecular weight distribution result in stickier materials. (Creton, 2003) It is expected that these adhesives will effectively capture microplastics with a significant polar component (in terms of their surface energy) (e.g., PET, 43 mJ / m 2 ; polyamide, 43 mJ / m 2 ).

[0086] The second class of adhesives is based on the need to bond to lower surface energy microplastics (e.g., PE, PP, etc.). More specifically, adhesives can be synthesized using different amounts of superhydrophobic side chains (e.g., perfluoroalkyl groups) blended with branched hydrocarbon side chains ( Figure 7, bottom). Perfluorinated polymers (e.g., poly(1,1 - pentadecafluoro - octyl acrylate)) have some of the lowest surface energies (10.4 mJ / m 2 ) for any polymer, and are far lower than the surface energies of PE (33 mJ / m 2 ) and micronized rubber (29 mJ / m 2 ). (Owens and Wendt, 1969)

[0087] Without wishing to be bound by any particular theory, it is believed that the adhesion strength of such adhesives will be high, resulting in effective capture of low - surface - energy microplastics. Another advantage of these hydrophobic materials is that the adhesive surface will repel water, which can block the surface and reduce microplastic capture. Water has a surface energy of 73 mJ / m 2 and forms a significant hydration layer on polar surfaces with similar high surface energies (e.g., polyethylene oxide, 43 mJ / m 2 ). (Sugden, 1924) The fluorinated adhesives prepared herein should exhibit significantly less surface hydration. Similarly, these materials will be synthesized from waste diapers / hygiene products.

[0088] One challenge in introducing these perfluoroalkyl groups is that they can raise the Tg too much, resulting in brittle materials. To overcome this problem, the "parachor" parameterization method can be used to estimate the minimum amount of perfluoroalkyl side chains required to reduce the surface energy. (Roe, 1965) For both classes of adhesives, contact - angle measurements on flat surfaces will be used to measure the surface energy. (Van Oss et al., 1986; Fowkes, 1962) In addition, rheology will be used to determine the viscoelasticity of the adhesives. (Chang, 1991)

[0089] These parameters (dynamic modulus (G') and loss modulus (G'')) provide a measure of the cohesion and viscosity of the adhesive when coated onto a substrate, as well as the ability to deform and capture microplastics. Differential scanning calorimetry can be used to measure the glass transition temperature (Tg), which also provides an understanding of the viscosity of the adhesive.

[0090] Next, probe - tack measurements will be performed to quantify the adhesion strength and peel work between the adhesive and the plastic. (Karnal et al., 2017) These measurements will be carried out in water using a multi - mode force microscope (MMFM), which measures the interaction force as a function of the interaction time. The probe tip will be made of common polymers in microplastic pollution (e.g., polyethylene, polyethylene terephthalate, polyamide, etc.). The ability of all synthesized adhesives to capture microplastics of different sizes, shapes, and types will be evaluated, as described in more detail below.

[0091] The above probe-adhesion measurements will provide an understanding of the macroscopic adhesion strength of each adhesive to each plastic in water. It is also possible to examine whether those adhesion strengths are proportional to the size and shape of the plastic particles. To this end, microplastics with different sizes and shapes will be synthesized or purchased. Microfibers can be prepared using a cryostat microtome, and spherical microplastics can be prepared by emulsification in water. Powders, beads, and pellets can be purchased and used as received, or homogenized or ground in a cryogenic mill.

[0092] A simple protocol has been developed for quantifying microplastic capture in agitated and unagitated aqueous solutions using an optical microscope and image analysis software (see, for example, Figure 2 , Figure 8 ). Briefly, an adhesive is coated onto a glass slide with a known surface area and then immersed in an aqueous suspension of microplastics with a known concentration for a specific period of time. After removal of the glass slide, a snapshot of the film surface on an optical microscope, followed by statistical analysis, can be used to estimate the capture efficiency of each adhesive based on the microplastic composition, size, and shape. While the primary focus is on optimizing the adhesive-microplastic interfacial interaction, the importance of the adhesive / clarified particle interaction cannot be ignored, especially for understanding how small-scale experiments translate to large-scale flocculation or skimming experiments.

[0093] The long-term goal is to develop chemical recycling pathways for the captured microplastics so that they can re-enter the value stream. The first step towards achieving this goal will be to develop methods for releasing the captured microplastics from the adhesive-coated particles. Fortunately, pressure-sensitive adhesives lose their adhesiveness when the temperature is lowered. Thus, temperature can be used, where simple abrasion can be used to brush off the microplastics without stripping the adhesive.

[0094] Alternatively, if the temperature is raised above the glass transition temperature, the adhesive will peel off the surface, taking the microplastics with it. The adhesive can then be selectively removed by dissolving in an organic solvent, enabling the insoluble microplastics to be separated by filtration or centrifugation. In either case, a mixture of microplastics of different sizes, shapes, and compositions will most likely be present. Some microplastics can be separated by density-based partitioning, and the mixed microplastics can be reused in park benches, carpet padding, and other composite materials. Compared to landfill materials, it is less desirable but still beneficial to incinerate the microplastics and recover the energy. Overall, the superabsorbent polymer-pressure-sensitive adhesive approach will be used to divert landfill-bound diapers so that they can re-enter the value chain while reducing a key source of microplastic pollution.

[0095] There is also a growing concern about the impact of microplastic pollution in indoor air and, to a lesser extent, outdoor air on human health, such as microplastics emitted from clothes dryers. To date, most air filtration devices are designed to capture larger particles by physical interception or electrostatically on a mesh, while much smaller particles easily pass through. In contrast, an adhesive-coated substrate (e.g., a polymer-based cylindrical 3D printed brush) should effectively capture microplastics and nanoplastics, including polymers of different sizes, shapes, or types, via adhesion (chemical interactions dominated by van der Waals forces).

[0096] In representative embodiments, for example, a three-dimensional (3D) article of the pressure-sensitive adhesive disclosed herein having a surface (e.g., a brush, a geometric solid shape, including but not limited to a rod, a brush, a sphere, an impeller, a rectangular slider, an oblate spheroid, a cube, a pyramid, a hexagon, an octagon, and combinations thereof, where the solid shape can be closed or open, etc.) can be used to filter microplastics and nanoplastics from indoor or outdoor air. The article is dip-coated with a thin layer of about 0.5 μm to about 5 μm, including layers of about 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, and 5.0 μm. In such embodiments, the 3D article can include protruding adhesive filaments. See, for example Figure 10 During implementation, the coated 3D article can be inserted into an air circulation device to effectively remove microplastics and nanoplastics.

[0097] Accordingly, in some embodiments, the subject matter disclosed herein provides a method for removing microplastic or nanoplastic particles from a medium, the method comprising contacting the microplastic or nanoplastic particles in the medium with an article comprising one or more pressure-sensitive adhesives, wherein the one or more pressure-sensitive adhesives comprise a compound of formula (I) or formula (II):

[0098]

[0099] wherein:

[0100] Each n is independently an integer from 1 to 10,000;

[0101] Each R1, R2, and R3, if present, is independently selected from the group consisting of:

[0102]

[0103] Wherein: each m is independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8; p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8; u is an integer selected from the group consisting of 1, 2, 3, 4, and 5; v is an integer selected from the group consisting of 1, 2, 3, and 4; w is an integer selected from the group consisting of 1, 2, and 3; each R4 is independently selected from the group consisting of: H, C1-C8 substituted or unsubstituted branched or straight-chain alkyl, hydroxy, C1-C8 alkoxy, amino, cyano, -CF3, carbonyl, carboxyl, C1-C8 alkynyl, acyl, carbamoyl, halogen, nitro, mercapto, and thiol; and R5 is C3-C 20 branched alkyl.

[0104] In certain embodiments, R1, R2, and R3 are each independently selected from the group consisting of:

[0105]

[0106] Wherein p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8.

[0107] In some aspects, the pressure-sensitive adhesive is made from recycled superabsorbent polymer (SAP). In certain aspects, the recycled SAP is degraded to poly(acrylic acid) (PAA); and wherein the PAA is derivatized to a pressure-sensitive adhesive. See, for example, U.S. Provisional Patent Application 62 / 890,880, filed Aug. 23, 2019, and entitled Depolymerization of Polymers, to Collias, D.I., Zimmerman, P.M., Chazovachii, P.T., Robo, M.T., and McNeil, A.J.; U.S. Patent Application Publication 20210054161, published Feb. 25, 2021, and entitled Depolymerization of Polymers, to Collias et al.; U.S. Provisional Patent Application 62 / 947,363, filed Dec. 12, 2019, and entitled Esterifying Polyacrylic Acid with High Conversion, to McNeil, A.J., Chazovachii, P.T., Robo, M.T., Marsh, N.G., Zimmerman, P.M., James, M.I., and Collias, D.I.; and U.S. Provisional Patent Application 62 / 890,943, filed Aug. 23, 2019, and entitled Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives, to Collias, D.I., Zimmerman, P., Chazovachii, P.T., Robo, M.T., McNeil, A.J.; WO2021041326, published Mar. 4, 2021, and entitled Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives, to Collias et al., and U.S. Patent Application Publication 20210054248, published Aug. 24, 2020, and entitled Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives, to Collias et al., each of which is incorporated herein by reference in its entirety. Specific embodiments are provided in Examples 3 and 4 herein below.

[0108] In certain embodiments, the microplastic or nanoplastic particles comprise a material selected from the group consisting of: rubber, poly(isoprene), polyamide, polyester, poly(ethylene), poly(propylene), polystyrene, nylon, cellulose, poly(ethylene terephthalate), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), poly(tetrafluoroethylene) (PTFE), polychlorotrifluoroethylene (PCTFE), perfluoroalkoxy alkane (PFA), fluorinated ethylene propylene (FEP), ethylene tetrafluoroethylene (ETFE), ethylene chlorotrifluoroethylene (ECTFE), perfluoroelastomer (FFPM / FFKM), chlorotrifluoroethylene - vinylidene fluoride (FPM / FKM), tetrafluoroethylene - propylene (FEPM), perfluoropolyether (PFPE), perfluorosulfonic acid (PFSA), perfluoropolyepoxybutane, and combinations thereof.

[0109] In certain embodiments, the medium is selected from the group consisting of an aqueous medium and an atmospheric medium. In more certain embodiments, the aqueous medium is selected from the group consisting of: wastewater effluent from a wastewater treatment plant, laundry wash effluent from a commercial laundry facility, laundry wash effluent from a personal washing machine, and fill water in a washing machine during or after a wash cycle.

[0110] In certain embodiments, the atmospheric environment is selected from the group consisting of: indoor air, outdoor air, and emissions, exhaust gases, and / or exhaust from commercial or personal dryers.

[0111] In other embodiments, the method further comprises removing microplastic or nanoplastic particles from one or more pressure - sensitive adhesives.

[0112] In some embodiments, the subject matter disclosed herein provides an article comprising one or more pressure - sensitive adhesives, wherein the one or more pressure - sensitive adhesives comprise a compound of formula (I) or formula (II):

[0113]

[0114] Wherein:

[0115] Each n is independently an integer from 1 to 10,000;

[0116] Each R1, R2, and R3, if present, is independently selected from the group consisting of:

[0117]

[0118] Wherein: each m is independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8; p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8; u is an integer selected from the group consisting of 1, 2, 3, 4, and 5; v is an integer selected from the group consisting of 1, 2, 3, and 4; w is an integer selected from the group consisting of 1, 2, and 3; each R4 is independently selected from the group consisting of: H, a C1-C8 substituted or unsubstituted branched or straight-chain alkyl group, a hydroxyl group, a C1-C8 alkoxy group, an amino group, a cyano group, -CF3, a carbonyl group, a carboxyl group, a C1-C8 alkynyl group, an acyl group, a carbamoyl group, a halogen, a nitro group, a mercapto group, and a thiol; and R5 is a C3-C 20 branched alkyl group.

[0119] In certain embodiments, R1, R2, and R3 are each independently selected from the group consisting of:

[0120]

[0121] wherein p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, and 8.

[0122] In certain aspects, the article comprises a pressure-sensitive adhesive made from recycled superabsorbent polymer (SAP). In a particular aspect, the recycled SAP degrades to poly(acrylic acid) (PAA); and wherein the PAA is derivatized to a pressure-sensitive adhesive.

[0123] In certain embodiments, the article includes a solid shape selected from the group consisting of: a rod, a brush, a sphere, an impeller, a rectangular slider, an oblate spheroid, a cube, a pyramid, a hexagon, an octagon, and combinations thereof, wherein the solid shape can be closed or open. In a more specific embodiment, the shape further includes protruding filaments coated with one or more pressure-sensitive filaments.

[0124] In additional embodiments, the article is included in an air circulation system or device.

[0125] In yet additional embodiments, the subject matter disclosed herein provides a washing machine or dryer that includes the article disclosed herein.

[0126] In other embodiments, the subject matter disclosed herein provides a kit that includes the article disclosed herein.

[0127] II. Definitions

[0128] Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the presently described subject matter pertains.

[0129] In accordance with long-standing patent law convention, the terms "a", "an", and "the" are used in this application, including the claims, to mean "one or more" or "one or more kinds". Thus, for example, unless the context clearly dictates otherwise (e.g., multiple subjects), reference to "a subject" includes multiple subjects, and so forth.

[0130] Throughout this specification and the claims, unless the context otherwise requires, the terms "comprise", "comprising", and "include" are used in a non-exclusive sense. Similarly, the term "include" and its grammatical variants are intended to be non-limiting, such that the recitation of items in a list does not exclude other similar items that may be substituted or added to the listed items.

[0131] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing quantities, sizes, dimensions, ratios, shapes, formulations, parameters, percentages, amounts, characteristics, and other numerical values used in the specification and claims are to be understood as being modified in all instances by the term "about", even if the term "about" may not explicitly appear with the value, amount, or range. Thus, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are not and need not be exact, but may be approximate and / or larger or smaller as desired, reflecting tolerances, conversion factors, rounding, measurement error, and the like, as well as other factors known to those of skill in the art, depending upon the desired characteristics sought to be obtained by the presently disclosed subject matter. For example, when referring to a value, the term "about" can mean encompassing variations of, in some embodiments, ±100% from the specified amount, in some embodiments ±50%, in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% because such variations are appropriate for carrying out the disclosed methods or using the disclosed compositions.

[0132] In addition, when used in conjunction with one or more numbers or numerical ranges, the term "about" shall be understood to refer to all such numbers, including all numbers within the range, and to modify the range by extending the boundaries above and below the recited numerical values. Narrative of a numerical range by endpoints includes all numbers within that range (e.g., integers, including their fractions (e.g., the narrative of 1 to 5 includes 1, 2, 3, 4, and 5, and their fractions, such as 1.5, 2.25, 3.75, 4.1, etc.)) and any range within that range.

[0133] While the following terms related to the compounds of formula (I) or formula (II) are considered to be well understood by those of ordinary skill in the art, the following definitions are set forth to facilitate the explanation of the subject matter disclosed herein. These definitions are intended to supplement and illustrate, rather than exclude, definitions that will be apparent to those of ordinary skill in the art upon reading this disclosure.

[0134] As used herein, the terms substituted (whether or not preceded by the term "optionally") and substituent refer to the ability of one skilled in the art to change one functional group on a molecule to another functional group, provided that the valence of all atoms is maintained. When more than one position in any given structure can be substituted by more than one substituent selected from a specified group, the substituents can be the same or different at each position. Substituents can also be further substituted (e.g., an aryl group substituent can have another substituent outside of it, such as another aryl group further substituted at one or more positions).

[0135] When a substituent group or a linking group is specified by its conventional chemical formula written from left to right, they equally cover the chemically identical substituents resulting from writing the structure from right to left, e.g., -CH2O- is equivalent to -OCH2-; -C(=O)O- is equivalent to -OC(=O)-; -OC(=O)NR- is equivalent to -NRC(=O)O-, and so on.

[0136] When the term "independently selected" is used, the recited substituents (e.g., R groups, such as groups R1, R2, etc., or variables, such as "m" and "n") can be the same or different. For example, both R1 and R2 can be substituted alkyls, or R1 can be hydrogen and R2 can be a substituted alkyl, etc.

[0137] The terms "a", "an", or "a(n)" when used herein in reference to a group of substituents mean at least one. For example, when a compound is "a" alkyl or aryl substituted, the compound is optionally substituted by at least one alkyl and / or at least one aryl. In addition, when a moiety is substituted by an R substituent, the group can be referred to as "R-substituted". When a moiety is R-substituted, the moiety is substituted by at least one R substituent, and each R substituent is optionally different.

[0138] Unless otherwise indicated herein, a moiety named “R” or a group will generally have a structure in the art that is considered to correspond to the group having that name. For purposes of illustration, certain representative “R” groups as set forth above are defined below.

[0139] The description of the compounds of the present disclosure is limited by the principles of chemical bonding known to those skilled in the art. Thus, when a group can be substituted by one or more of a number of substituents, such substitution is selected so as to comply with the principles of chemical bonding and to give compounds that are not inherently unstable and / or that are not likely to be unstable under environmental conditions such as aqueous, neutral, and several known physiological conditions.

[0140] Unless otherwise expressly defined, “substituent group” as used herein includes one or more functional groups selected from the following moieties, which are defined herein:

[0141] As used herein, the term hydrocarbon refers to any chemical group containing hydrogen and carbon. The hydrocarbon can be substituted or unsubstituted. As is known to those skilled in the art, all valences must be satisfied when making any substitution. The hydrocarbon can be unsaturated, saturated, branched, unbranched, cyclic, polycyclic, or heterocyclic. Exemplary hydrocarbons are further defined below and include, for example, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, allyl, vinyl, n-butyl, tert-butyl, ethynyl, cyclohexyl, and the like.

[0142] Unless otherwise indicated, the term “alkyl” by itself or as part of another substituent means a straight-chain (i.e., unbranched) or branched, acyclic or cyclic hydrocarbon group or combinations thereof, which can be fully saturated, mono-unsaturated, and / or poly-unsaturated, and can include divalent and polyvalent groups, having the specified number of carbon atoms (i.e., C 1-10 means one to ten carbons, including 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 carbons). In a specific embodiment, the term “alkyl” refers to C 1-20 (including the end values, including 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 carbons) linear (i.e., “straight-chain”), branched, or cyclic saturated or at least partially saturated and in some cases fully unsaturated (i.e., alkenyl and alkynyl) hydrocarbon groups, which are derived by removing a single hydrogen atom from a hydrocarbon moiety containing one to twenty carbon atoms.

[0143] Representative saturated hydrocarbon groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, neopentyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, n-decyl, n-undecyl, dodecyl, cyclohexyl, (cyclohexyl)methyl, cyclopropylmethyl, and their homologs and isomers.

[0144] "Branched chain" refers to an alkyl group in which a lower alkyl group (such as methyl, ethyl, or propyl) is attached to a linear alkyl chain. "Lower alkyl" refers to an alkyl group having 1 to about 8 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7, or 8 carbon atoms) (i.e., C 1-8 alkyl). "Higher alkyl" refers to an alkyl group having about 10 to about 20 carbon atoms (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms). In certain embodiments, "alkyl" specifically refers to C 1-8 straight-chain alkyl. In other embodiments, "alkyl" specifically refers to C 1-8 branched-chain alkyl.

[0145] An alkyl group may optionally be substituted with one or more alkyl group substituents that may be the same or different ("substituted alkyl"). The term "alkyl group substituent" includes, but is not limited to, alkyl, substituted alkyl, halo, arylamino, acyl, hydroxy, aryloxy, alkoxy, alkylthio, arylthio, aralkoxy, aralkylthio, carboxy, alkoxycarbonyl, oxo, and cycloalkyl. One or more oxygen, sulfur, or substituted or unsubstituted nitrogen atoms may optionally be inserted along the alkyl chain, where the nitrogen substituent is hydrogen, lower alkyl (also referred to herein as "alkylaminoalkyl"), or aryl.

[0146] Thus, as used herein, the term "substituted alkyl" includes an alkyl group as defined herein, where one or more atoms or functional groups of the alkyl group are replaced by another atom or functional group, including, for example, alkyl, substituted alkyl, halogen, aryl, substituted aryl, alkoxy, hydroxy, nitro, amino, alkylamino, dialkylamino, sulfate, cyano, and mercapto.

[0147] Unless otherwise specified, the term "heteroalkyl" by itself or in combination with another term means a stable straight or branched chain, or a cyclic hydrocarbon group having from 1 to 20 carbon atoms or heteroatoms, or a combination thereof having from 3 to 10 carbon atoms or heteroatoms, which is composed of at least one carbon atom and at least one heteroatom selected from the group consisting of O, N, P, Si, and S, and in which the nitrogen, phosphorus, and sulfur atoms may optionally be oxidized and the nitrogen heteroatom may optionally be quaternized. The heteroatoms O, N, P, S, and Si may be located at any internal position of the heteroalkyl group or at the position where the alkyl group is attached to the remainder of the molecule. Examples include but are not limited to -CH2-CH2-O-CH3, -CH2-CH2-NH-CH3, -CH2-CH2-N(CH3)-CH3, -CH2-S-CH2-CH3, -CH2-CH2-S(O)-CH3, -CH2-CH2-S(O)2-CH3, -CH=CH-O-CH3, -Si(CH3)3, -CH2-CH=N-OCH3, -CH=CH-N(CH3)-CH3, O-CH3, -O-CH2-CH3, and -CN. Up to two or three heteroatoms may be consecutive, such as, for example, -CH2-NH-OCH3 and -CH2-O-Si(CH3)3.

[0148] As described above, the heteroalkyl groups used herein include those groups that are attached to the remainder of the molecule through a heteroatom, such as -C(O)NR', -NR'R", -OR', -SR, -S(O)R, and / or -S(O2)R'. In the case where "heteroalkyl" is recited followed by a specific heteroalkyl group, such as -NR'R, etc., it should be understood that the terms heteroalkyl and -NR'R" are not redundant or mutually exclusive. Instead, the specific heteroalkyl group is recited for increased clarity. Thus, the term "heteroalkyl" should not be construed herein to exclude specific heteroalkyl groups, such as -NR'R", etc.

[0149] An unsaturated hydrocarbon has one or more double or triple bonds. Examples of unsaturated alkyl groups include but are not limited to vinyl, 2-propenyl, crotyl, 2-isopentenyl, 2-(butadienyl), 2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1-propynyl, and 3-propynyl, 3-butynyl, and higher homologs and isomers. An alkyl group restricted to hydrocarbon groups is called a "homologous alkyl".

[0150] More specifically, as used herein, the term "alkenyl" refers to a C derived by removing a single hydrogen molecule from a compound having at least one carbon-carbon double bond 2-20A monovalent group of a straight-chain or branched-chain hydrocarbon moiety (including terminal values). Examples of alkenyl groups include ethenyl (i.e., vinyl), propenyl, butenyl, 1-methyl-2-buten-1-yl, pentenyl, hexenyl, octenyl, allene-based groups, and butadiene-based groups.

[0151] As used herein, the term "alkynyl" refers to a monovalent group derived from a straight-chain or branched-chain C hydrocarbon having a specified number of carbon atoms and containing at least one carbon-carbon triple bond. 2-20 Examples of "alkynyl" include ethynyl, 2-propynyl (propargyl), 1-propynyl, pentynyl, hexynyl, and heptynyl groups, among others.

[0152] The term "alkylene", either by itself or as part of another substituent, refers to a straight-chain or branched-chain divalent aliphatic hydrocarbon group derived from an alkyl group having 1 to about 20 carbon atoms, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 carbon atoms. The alkylene group can be straight-chain, branched-chain, or cyclic. The alkylene group can also optionally be unsaturated and / or substituted by one or more "alkyl group substituents". One or more oxygen, sulfur, or substituted or unsubstituted nitrogen atoms (also referred to herein as "alkylaminoalkyl") can be optionally inserted along the alkylene group, where the nitrogen substituent is an alkyl as previously described. Exemplary alkylene groups include methylene (–CH2–); ethylene (–CH2–CH2–); propylene (–(CH2)3–); cyclohexylene (–C6H 10 –); –CH=CH–CH=CH–; –CH=CH–CH2–; -CH2CH2CH2CH2-, -CH2CH=CHCH2-, -CH2CsCCH2-, -CH2CH2CH(CH2CH2CH3)CH2-, -(CH2) q -N(R)-(CH2) r –, where each of q and r is independently an integer from 0 to about 20, such as 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20, and R is hydrogen or a lower alkyl; methylenedioxy (–O–CH2–O–); and ethylenedioxy (-O-(CH2)2–O–). The alkylene group can have about 2 to about 3 carbon atoms and can further have 6 - 20 carbons. Generally, an alkyl (or alkylene) group will have 1 to 24 carbon atoms, and those groups having 10 or fewer carbon atoms are some embodiments of the present disclosure. "Lower alkyl" or "lower alkylene" are shorter-chain alkyl or alkylene groups that generally have eight or fewer carbon atoms.

[0153] As used herein, a structure generally represented by the following formula:

[0154]

[0155] refers to a ring structure, such as but not limited to 3-carbon, 4-carbon, 5-carbon, 6-carbon, 7-carbon, etc., aliphatic and / or aromatic cyclic compounds, including saturated ring structures, partially saturated ring structures and unsaturated ring structures, containing substituent R groups, where the R groups may or may not be present, and when present, one or more R groups may each be substituted on one or more available carbon atoms of the ring structure. The presence or absence of the R groups and the number of R groups are determined by the value of the variable "n", which is an integer generally having a value in the range of 0 to the number of carbon atoms available for substitution on the ring. If there are more than one, each R group is substituted on the available carbon of the ring structure rather than on another R group. For example, the above structure where n is from 0 to 2 will include compound groups, including but not limited to:

[0156]

[0157] and so on.

[0158] The symbol represents the point of attachment of the moiety to the rest of the molecule. [[ID=I9]]

[0159] When a designated atom of an aromatic or heteroaromatic ring is defined as "absent", the designated atom is replaced by a direct bond.

[0160] As used herein, the term "acyl" refers to an organic acid group in which the -OH of the carboxyl group has been replaced by another substituent and has the general formula RC(=O)-, where R is an alkyl, alkenyl, alkynyl, aryl, carbocyclic, heterocyclic or aromatic heterocyclic group as defined herein. Thus, the term "acyl" specifically includes arylacyl groups, such as 2-(furan-2-yl)acetyl)- and 2-phenylacetyl groups. Specific examples of acyl groups include acetyl and benzoyl. The acyl group is also intended to include amides, -RC(=O)NR', esters, -RC(=O)OR', ketones, -RC(=O)R' and aldehydes, -RC(=O)H.

[0161] The terms "alkoxyl" or "alkoxy" are used interchangeably herein and refer to a saturated (i.e., alkyl–O–) or unsaturated (i.e., alkenyl–O– and alkynyl–O–) group attached to the parent molecular moiety through an oxygen atom, where the terms "alkyl", "alkenyl" and "alkynyl" are as previously described, and may include C 1-20(including the end values) linear, branched or cyclic saturated or unsaturated oxo hydrocarbon chains, including, for example, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, sec-butoxy, tert-butoxy, and n-pentyloxy, neopentyloxy, n-hexyloxy, etc.

[0162] "Carbamoyl" refers to the amide group of the formula –C(=O)NH2. "Alkylcarbamoyl" refers to the group R’RN–C(=O)–, where one of R and R' is hydrogen and the other of R and R' is an alkyl and / or substituted alkyl as described previously. "Dialkylcarbamoyl" refers to the group R’RN–C(=O)–, where each of R and R' is independently an alkyl and / or substituted alkyl as described previously.

[0163] The term "amino" refers to the –NH2 group and also to nitrogen-containing groups known in the art that are derived from ammonia by replacing one or more hydrogen groups with organic groups. For example, the terms "acylamino" and "alkylamino" refer to specific N-substituted organic groups having acyl and alkyl substituent groups, respectively.

[0164] The term "carbonyl" refers to the –C(=O)– group and may include an aldehyde group represented by the general formula R-C(=O)H.

[0165] The term "carboxyl" refers to the -COOH group. Such groups are also referred to herein as "carboxylic acid" moieties.

[0166] The term "cyano" refers to the -C≡N group.

[0167] As used herein, the terms "halo", "halide" or "halogen" refer to fluoro, chloro, bromo and iodo groups. Additionally, terms such as "haloalkyl" are meant to include both monohaloalkyl and polyhaloalkyl. For example, the term "halo(C 1-4 )alkyl" is intended to include, but is not limited to, trifluoromethyl, 2,2,2-trifluoroethyl, 4-chlorobutyl, 3-bromopropyl, etc.

[0168] The term "hydroxy" refers to the –OH group.

[0169] The term "mercapto" refers to the –SH group.

[0170] The term "nitro" refers to the –NO2 group.

[0171] The term "thio" refers to a compound as described previously herein in which a carbon or oxygen atom is replaced by a sulfur atom.

[0172] Examples

[0173] The following examples have been included to provide guidance to a person of ordinary skill in the art for practicing representative embodiments of the subject matter disclosed herein. Based on the present disclosure and the general level of those skilled in the art, one skilled in the art can understand that the following examples are only intended to be exemplary, and many changes, modifications, and variations can be made without departing from the scope of the subject matter disclosed herein. The following synthetic descriptions and specific examples are for illustrative purposes only and should not be construed as limiting the preparation of the compounds disclosed herein by any other method.

[0174] Example 1

[0175] Synthesis of Poly(2-ethylhexyl acrylate)

[0176] The adhesives disclosed in the present invention can be synthesized by esterifying poly(acrylic acid) or polymerizing various (meth)acrylate monomers (Scheme I).

[0177]

[0178] Scheme I shows a representative pressure-sensitive adhesive, which can be prepared by esterifying polyacrylic acid, where R 1 , R 2 and R 3 are derived from representative alcohols.

[0179] In this example, poly(2-ethylhexyl acrylate) adhesive was synthesized by esterifying poly(acrylic acid). The adhesive was used to test the underwater adhesion of polyethylene, micronized rubber (poly(isoprene)), and poly(ethylene terephthalate). The adhesive was coated onto a glass slide and immersed in a 50-mL centrifuge tube containing microplastics (1 mg) dispersed in deionized water (15 mL). As Figure 8 can be seen, only microplastics with a similar low such as polyethylene adhered.

[0180] Example 2

[0181] Adhesives for Microplastics in the Presence of Detergents

[0182] The poly(2-ethylhexyl acrylate) adhesive was coated onto a glass slide and immersed in a 50-mL centrifuge tube containing polyethylene (1 mg) dispersed in deionized water, 0.1% detergent, and 1% detergent (15 mL) ( Figure 9 ). These data indicate that the pressure-sensitive adhesives disclosed in the present invention are capable of capturing microplastics in laundry wash effluents at the actual concentrations of laundry detergents.

[0183] Example 3

[0184] Recycling of Superabsorbent Polymers as Pressure-Sensitive Adhesives

[0185] In one embodiment, the pressure-sensitive adhesive is prepared by the method disclosed in U.S. Patent Application 62 / 890,943, "Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives", filed on August 23, 2019; WO2021041326, entitled "Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives", granted to Collias et al. and published on March 4, 2021; and U.S. Patent Application Publication 20210054248, entitled "Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives", granted to Collias et al. and published on August 24, 2020, each of which is incorporated herein by reference in its entirety. In such embodiments, the method includes de-crosslinking, sonication-induced depolymerization, and base-catalyzed co-esterification, and an optional deprotection step. The method achieves a high molecular weight polyacrylate-based PSA with a molecular weight of from about 400 kg / mol to about 900 kg / mol.

[0186] More specifically, in one embodiment, a method for preparing a pressure-sensitive adhesive from one or more sodium polyacrylate-based superabsorbent polymers includes: (a) providing a solution comprising one or more sodium polyacrylate-based superabsorbent polymers; (b) de-crosslinking the one or more sodium polyacrylate-based superabsorbent polymers to provide one or more de-crosslinked sodium polyacrylate-based superabsorbent polymers; (c) optionally sonicating the one or more de-crosslinked sodium polyacrylate-based superabsorbent polymers to provide one or more chain-shortened sodium polyacrylate-based superabsorbent polymers; (d) protonating the one or more de-crosslinked and / or chain-shortened sodium polyacrylate-based superabsorbent polymers to provide one or more protonated de-crosslinked and / or chain-shortened polyacrylic acid-based superabsorbent polymers; and (e) esterifying the one or more protonated de-crosslinked and / or chain-shortened polyacrylic acid-based superabsorbent polymers to provide the pressure-sensitive adhesive.

[0187] In certain embodiments, the method is illustrated in Scheme II:

[0188]

[0189] wherein: RX is an alkyl halide; TMG is 1,1,3,3-tetramethylguanidine (Ga(CH3)3), and DMSO is dimethyl sulfoxide.

[0190] In certain embodiments, the de-crosslinking of one or more polyacrylate-based superabsorbent polymers comprises contacting the one or more polyacrylate-based superabsorbent polymers with a base to provide one or more de-crosslinked polyacrylate-based superabsorbent polymers. In certain embodiments, the base is an inorganic base. In more certain embodiments, the inorganic base is selected from the group consisting of NaOH, KOH, Na2CO3, and K2CO3.

[0191] In some embodiments, the method comprises removing the base from the one or more de-crosslinked polyacrylate-based superabsorbent polymers. In a specific embodiment, removing the base from the one or more de-crosslinked polyacrylate-based superabsorbent polymers comprises dialyzing the one or more de-crosslinked polyacrylate-based superabsorbent polymers using a molecular porous membrane tube. Those of ordinary skill in the art will recognize that other ultrafiltration methods based on size exclusion will be suitable for use with the methods disclosed herein. Non-limiting examples of desalination processes are membrane processes (e.g., reverse osmosis, forward osmosis, electrodialysis reversal (EDR), nanofiltration, etc.), freeze desalination, solar desalination, geothermal desalination, ion exchange, wave power desalination, etc.

[0192] In some embodiments, the de-crosslinking of one or more polyacrylate-based superabsorbent polymers comprises partially de-crosslinking the one or more polyacrylate-based superabsorbent polymers.

[0193] In some embodiments, the method further comprises filtering the one or more de-crosslinked polyacrylate-based superabsorbent polymers to remove residual crosslinked polyacrylate-based superabsorbent polymers therefrom.

[0194] In a specific embodiment, the protonation of one or more de-crosslinked polyacrylate-based superabsorbent polymers comprises contacting the one or more de-crosslinked polyacrylate-based superabsorbent polymers with a cation exchange resin to provide one or more protonated polyacrylate-based superabsorbent polymers. In a more specific embodiment, the cation exchange resin comprises a sulfonic acid functional group.

[0195] In certain embodiments, the esterification of one or more protonated polyacrylate-based superabsorbent polymers comprises contacting the one or more protonated polyacrylate-based superabsorbent polymers with one or more organic halide compounds. In more certain embodiments, the one or more organic halide compounds include primary or secondary organic halide compounds. In more certain embodiments, the primary or secondary organic halide compounds contain at least one halogen atom selected from the group consisting of Cl, Br, and I. In even more certain embodiments, the primary or secondary organic halide compounds contain C1-C 12Straight-chain or branched-chain alkyl groups. In a specific embodiment, one or more organic halide compounds are selected from the group consisting of: methyl iodide, ethyl iodide, n-butyl bromide, n-octyl bromide, propargyl bromide (3-bromo-1-propyne), ethyl bromoacetate, ethyl chloroacetate, (1-bromoethyl)benzene, benzyl chloride, benzyl bromide, isobutenyl chloride (3-chloro-2-methylprop-1-ene), 2-ethylhexyl bromide, and 2-ethylhexyl chloride.

[0196] In some embodiments, one or more organic halide compounds comprise a protecting group to provide one or more protected esterified protonated polyacrylate-based superabsorbent polymers. In a specific embodiment, the protecting group is selected from the group consisting of tert-butoxycarbonyl (BOC), 9-fluorenylmethoxycarbonyl (FMOC), and the like. In such embodiments, the method disclosed in the present invention further includes deprotecting one or more protected esterified protonated polyacrylate-based superabsorbent polymers.

[0197] In some embodiments of the method disclosed in the present invention, esterifying one or more protonated polyacrylate-based superabsorbent polymers includes contacting one or more protonated polyacrylate-based superabsorbent polymers with one or more promoters. In certain embodiments, one or more promoters are selected from the group consisting of 1,1,3,3-tetramethylguanidine (TMG), triethylamine, and pyridine.

[0198] In some embodiments of the method disclosed in the present invention, esterifying one or more protonated polyacrylate-based superabsorbent polymers is carried out in a polar aprotic solvent. In certain embodiments, the polar aprotic solvent is selected from the group consisting of dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF).

[0199] Example 4

[0200] Method for Esterifying Polyacrylic Acid with High Conversion Rate

[0201] In another embodiment, the pressure-sensitive adhesive is prepared by the methods disclosed in U.S. Patent Application 62 / 947,363, "Esterifying Polyacrylic Acid with High Conversion", filed December 12, 2019; WO2021041326, "Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives", granted to Collias et al. and published on March 4, 2021; and U.S. Patent Application Publication 20210054248, "Super Absorbent Polymer Recycling to Pressure Sensitive Adhesives", granted to Collias et al. and published on August 24, 2020, each of which is incorporated herein by reference in its entirety. This method achieves high esterification without the need to remove water from the reaction.

[0202] Fisher esterification is widely used to alkylate carboxylic acids for a variety of applications because it is cost-saving and more environmentally friendly than alternatives. However, water, which is a reaction byproduct of Fisher esterification, can react with the desired product to reform the starting material. This byproduct reaction thus results in low conversion. Due to this challenge, most Fisher esterification methods known in the art include removing water from the reaction mixture to drive the reaction forward.

[0203] Unlike the esterification methods of small molecules hindered by water, high esterification of polyacrylic acid can be achieved within three hours without removing water. This result can be achieved at an alcohol-to-acrylic acid ratio as low as 1:2 equivalents. As provided in more detail below, in some embodiments, a 1:1 ratio of ethanol to water (in a pressure vessel to avoid water escape) is used and high esterification is still achieved.

[0204] Contrary to the method shown in Scheme II immediately above, an alternative method for preparing PSA from PAA is shown in Scheme III:

[0205]

[0206] where ROH is an alcohol, and is a strong acid. Thus, this method involves heating in the presence of a strong acid to esterify the carboxylic acid functional group with an alcohol (e.g., ROH).

[0207] Furthermore, high esterification can be achieved using this method, for example, when R1 is 2-ethylhexyl, as shown in Scheme IIIa:

[0208]

[0209] The poly(2-ethylhexyl acrylate) (PSA) formed by the method of Scheme IIIa is soluble in alcohol after 3 hours, while the polyacrylic acid (PAA) starting material is insoluble in alcohol. High conversion rates can be achieved regardless of the amount of alcohol used.

[0210] In addition, it has been found that the presence of water does not significantly impede the esterification of the polymer. In some embodiments, the reaction is run in a pressure vessel to prevent the escape of water (Scheme IV).

[0211]

[0212] Scheme IV. Run the exemplary reaction in a pressure vessel to prevent the escape of water.

[0213] Thus, in some embodiments, a method for preparing a pressure-sensitive adhesive from one or more sodium polyacrylate-based superabsorbent polymers comprises: (a) providing one or more sodium polyacrylate-based superabsorbent polymers; and (b) contacting the one or more sodium polyacrylate-based superabsorbent polymers with one or more alcohols at a predetermined temperature in the presence of an acid for a period of time to provide a pressure-sensitive adhesive.

[0214] In certain embodiments, the one or more alcohols are selected from the group consisting of 2-ethylhexanol, 3-bromopropanol, and combinations thereof. In a specific embodiment, the one or more alcohols are 2-ethylhexanol.

[0215] One of ordinary skill in the art will appreciate that the methods disclosed herein can be used with one or more alkyl alcohols. As used herein, unless otherwise specified, the term "alkyl" means a straight-chain (i.e., unbranched) or branched, acyclic or cyclic hydrocarbon group or combinations thereof, which may be fully saturated, monounsaturated, or polyunsaturated, and may include divalent and polyvalent groups, having a specified number of carbon atoms (i.e., C1-C 10 means one to ten carbons). In a specific embodiment, the term "alkyl" refers to C1-C 20 (including the end values) linear (i.e., "straight-chain"), branched, or cyclic saturated or at least partially saturated in some cases fully unsaturated (i.e., alkenyl and alkynyl) hydrocarbon groups, which are derived by removing a single hydrogen atom from a hydrocarbon moiety containing one to twenty carbon atoms.

[0216] Representative saturated hydrocarbon groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl, neopentyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, n-decyl, n-undecyl, dodecyl, cyclohexyl, (cyclohexyl)methyl, cyclopropylmethyl, and homologs and isomers thereof.

[0217] "Branched chain" refers to an alkyl group in which a lower alkyl group (such as methyl, ethyl or propyl) is attached to a linear alkyl chain. "Lower alkyl" refers to an alkyl group having from 1 to about 8 carbon atoms (e.g., 1, 2, 3, 4, 5, 6, 7 or 8 carbon atoms) (i.e., C 1-8 alkyl). "Higher alkyl" refers to an alkyl group having from about 10 to about 20 carbon atoms (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 carbon atoms). In certain embodiments, "alkyl" specifically refers to C 1-8 straight-chain alkyl. In other embodiments, "alkyl" specifically refers to C 1-8 branched-chain alkyl.

[0218] The alkyl group may optionally be substituted with one or more alkyl group substituents (which may be the same or different) ("substituted alkyl"). The term "alkyl group substituent" includes, but is not limited to, alkyl, substituted alkyl, halo, arylamino, acyl, hydroxy, aryloxy, alkoxy, alkylthio, arylthio, aralkyl-oxy, aralkylthio, carboxy, alkoxycarbonyl, oxo and cycloalkyl.

[0219] Accordingly, the methods disclosed herein are applicable to alkyl alcohols including, but not limited to, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-pentanol, sec-pentanol, isopentanol, neopentanol, n-hexanol, sec-hexanol, n-heptanol, n-octanol, n-decanol, n-undecanol, dodecanol, each of which may be substituted with one or more substituent groups including straight-chain or branched-chain alkyl or halo. As used herein, the terms "halo", "halide" or "halogen" refer to fluoro, chloro, bromo and iodo groups.

[0220] In some embodiments, the acid includes inorganic acids. In other embodiments, the acid includes organic acids. Representative inorganic acids include, but are not limited to, hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, boric acid, hydrofluoric acid, hydrobromic acid, perchloric acid and hydroiodic acid. In a specific embodiment, the inorganic acid is sulfuric acid. Representative organic acids include, but are not limited to, arylsulfonic acids such as benzenesulfonic acid, toluenesulfonic acid, p-styrenesulfone, 2-naphthalenesulfonic acid, 4-hydroxybenzenesulfonic acid, 5-sulfosalicylic acid, p-dodecylbenzenesulfonic acid, dihexylbenzenesulfonic acid, 2,5-dihexylbenzenesulfonic acid, dibutylnaphthalenesulfonic acid, 6,7-dibutyl-2-naphthalenesulfonic acid, dodecylnaphthalenesulfonic acid, 3-dodecyl-2-naphthalenesulfonic acid, hexylnaphthalenesulfonic acid, 4-hexyl-1-naphthalenesulfonic acid, octylnaphthalenesulfonic acid, 2-octyl-1-naphthalenesulfonic acid, hexylnaphthalenesulfonic acid, 7-hexyl-1-naphthalenesulfonic acid, 6-hexyl-2-naphthalenesulfonic acid, dinonylnaphthalenesulfonic acid, 2,7-dinonyl-4-naphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, 2,7-dinonyl-4,5-naphthalenedisulfonic acid, etc.

[0221] In certain embodiments, the acid is selected from the group consisting of toluenesulfonic acid and sulfuric acid.

[0222] In certain embodiments, one or more alcohols are present in a ratio of about 1:2 relative to the acrylic acid repeat units of one or more sodium polyacrylate-based superabsorbent polymers. In certain embodiments, one or more alcohols are present in a ratio of about 1:1 relative to the amount of water.

[0223] In some embodiments, the predetermined temperature ranges from about 60°C to about 180°C, including 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, and 180°C. In a specific embodiment, the predetermined temperature is about 120°C.

[0224] In some embodiments, the period of time ranges from about 1 hour to about 8 hours, including 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, and 8 hours. In a specific embodiment, the period of time is about three hours. In a more specific embodiment, the method does not require a step of removing water. In an even more specific embodiment, the method is carried out in a pressure vessel.

[0225] Example 5

[0226] Adhesive-Coated Beads as Substrates for Effective Microplastic Removal

[0227] 5.1 Preliminary Results

[0228] Now referring to Figure 11 , preliminary experiments demonstrated the removal of microplastics from water using an adhesive-coated stir bar to capture micronized rubber suspended in water, and nylon and PET captured using an adhesive-coated glass slide at different initial microplastic concentrations. Next, methods for improving the microplastic (MP) removal efficiency (RE) disclosed herein by increasing the frequency of PSA-MP collisions were explored. Without being bound by any particular theory, it is believed that using adhesive-coated small spherical objects will increase the frequency of collisions due to the increased available surface area and increased mobility relative to the flat and stationary glass slides in the previous examples. While exploring this idea, it is important to note that the beads may be too small to generate sufficient force, and in these cases, the depolymerization of agglomerates occurs after applying the adhesive.

[0229] In preliminary experiments, 2-mm used molecular sieves found in the laboratory were dip-coated and evaluated for capturing 300-μm PET and 90-μm PS. Although the binder-coated sieves initially aggregated, immediate disaggregation was observed within 30 seconds of gentle manual shaking (3 shakes per second). The disaggregation may be due to the hindrance of the captured microplastics to the binder surface. The sieves were analyzed using scanning electron microscopy (SEM), and indeed, the sieves effectively captured PET( Figure 12 a and Figure 12 b) and PS( Figure 12 c and Figure 12 d) both. After noting the presence of some debris released from the sieves, zirconium silicate beads (0.5 mm) were used for the next experiment. Even under high-impact activities such as ball milling, the dense metal beads are not prone to material shedding.

[0230] Using binder-coated zirconium beads, the efficacy of removing 90-μm PS over time under saturated conditions (i.e., using a large excess of MPs) was studied. MP removal was induced by vortex mixing the samples at the 10 / 10 setting for durations ranging from 0.5 minutes to 2 minutes, and the results were analyzed using an optical microscope. Based on the optical microscope images, it was confirmed that MPs were removed using binder-coated zirconium silicate beads, which are made of different materials and are smaller than the previously used sieves.

[0231] 5.2 Identification of Flow Cytometry as a Method for Quantifying Removal Efficiency

[0232] In the previous examples, optical and scanning electron microscopy techniques were used to analyze the MPs captured by the binder-coated substrates. Thereby, an assessment of the MP RE of the method was sought. Due to the small size and extremely low concentration of MPs in the removal tests (i.e., after remediation), a reliable quantitative method needed to be determined. As in the previously highlighted examples, the quantitative methods commonly used in the art for evaluating microplastic removal vary widely, making it challenging to make an overall comparison of the results. UV-Vis spectroscopy has been used for microplastic quantification (Zhang et al., 2018; Mitzel et al., 2016), but this method can provide inaccurate results because suspended particles tend to scatter light rather than absorb it. (Chemistry LibreTexts, 2021) Although the hemocytometer method has also been used for microplastic quantification and can be very precise within its detection limit, the lower limit of detection is too high (i.e., ∼2.5×10 5 counts / mL) to accurately determine the tests after microplastic removal. (Bio-Rad, 2021)

[0233] Flow cytometry is a practical and relatively precise method for quantifying the concentration of MPs in an aqueous suspension. (Jaroszeski and Radcliff, 1999) The Attune NxT flow cytometer used in these experiments can analyze concentrations ranging from as low as 500 particles / mL to as high as 1,000,000 particles / mL. This technique, which is most commonly used in the fields of microbiology and biomedical engineering, allows researchers to analyze individual cell populations and quickly retrieve data on many parameters of those cells (i.e., cell type, size, surface characteristics, morphology, immunological activity, etc.). (Colson and Michel, 2021, Kaile et al., 2020) The working principle of flow cytometry technology ( Figure 14 a) involves using sheath fluid to hydrodynamically focus the flow of events (which can be cells, particles, or other discrete materials) in a single line in front of a laser, where these events are then detected, counted, and / or classified. Typically, researchers working with cellular organisms will stain the cell membrane with dye-conjugated antibodies to sort the population of interest.

[0234] For this application, fluorescence staining is not necessary because the only population in the sample is monodisperse MPs. Therefore, a forward scatter (FSC) detector, namely a photomultiplier tube, which analyzes events proportional to the size of the event, is employed. Forward scatter light is detected along the direction of the laser beam and is the result of light diffraction from the perimeter of the event. Another detector (side scatter detector) measures the scatter perpendicular to the laser beam and provides information about the internal complexity of the event. Since MPs have a simple internal structure composed of solid, densely packed polystyrene (PS) material, the forward scatter detector is used for data analysis.

[0235] After multiple trial-and-error methods, the instrument settings were completed as follows: laser voltage: 200, sample flow rate: 25 μL / min (for 5-μm and 10-μm sized particles), sample volume: 30 μL. To calculate the concentration, the number of events is divided by the volume of the sample collected and scaled to find the number of particles per milliliter.

[0236] The total number of events includes not only single peaks but also double and triple peaks. The single peak is a single event picked up by the detector as particles pass by one by one. Although the aim of flow cytometry analysis is to analyze events one by one as they pass through the laser interrogation point (such that all events can be represented as single peaks), sometimes, during analysis, two or three events will cluster together, resulting in the presence of double or triple peaks on scatter plots and histograms. As Figure 13As shown, from the simulated sample showing 10-μm beads, the maximum percentage of events in the sample is represented as a single peak (∼48%), while the combined samples with double and triple peaks form less than 15%. The double and triple peaks can be identified by the magnitude of the FSC area. Although the event peaks have the same FSC height (intensity) as the single peak due to their similar size, the areas of the peaks will be approximately twice and three times the area of the single peak, respectively, Figure 13 on the y-axis and Figure 14 ). The events represented by "others" are those smaller than the microplastic beads, and this event is the most likely evidence of the adhesive peeling off the beads during vial agitation.

[0237] 5.3 Effects of Time and Adhesive Molar Mass on Removal Efficiency

[0238] As discussed above, molar mass is key to the performance of pressure-sensitive adhesives. The softness required for the PSA to rapidly wet the substrate is most impartable at low molar mass (e.g., <400 kg / mol), while high molar mass (e.g., >500 kg / mol) is required for shear retention and cohesion. For this purpose, comparative tests were conducted on four PSAs with molecular weights in the range of 92 kg / mol–950 kg / mol for microplastic removal. The suspended microplastics were monodisperse 10-μm PS, which made it easier to identify single peaks and various multiplets and also to distinguish from foreign particles in flow cytometry measurements. To obtain a uniform MP suspension for more precise quantification, 20% ethanol was added to the formulation to reduce the surface tension of water, which is an acceptable practice in the art. (Chen et al., 2020) The samples were manually shaken at 3 shakes / second for an appropriate amount of time (0.5 minute, 1 minute, 3 minutes, and 5 minutes), and the suspension was transferred to an Eppendorf tube using a needle (18G) and syringe, and aliquots (1 mL) were analyzed using flow cytometry.

[0239] Within the first 30 s, P(2-EHA) Sigma-92k reproducibly exhibited a significant 80% RE, while the other adhesives were in the range of 40%–60% Figure 15 a). The trend observed may be due to the Sigma-92k excellent tacky properties of P(2-EHA), which are imparted by its low molar mass. Finally, P(2-EHA) Sigma-92k and P(2-EHA) P&G-450k had >98% RE, followed by P(2-EHA) SPP-950k with 96% RE, and P(2-EHA) Sigma-450k with 92% RE. It is noteworthy that, despite having similar molar mass and dispersity, P(2-EHA) developed from recycled polymersP&G-450k Better than P(2-EHA) Sigma-450k Performed better. Since these PSAs were prepared from different sources, the performance variations may be due to slight differences in the degree of esterification (e.g., residual carboxylic acid groups) or structural effects (e.g., branched vs. linear chains).

[0240] While gating samples in flow cytometry measurements, strange peaks that were not identified as any possible multiplets (i.e., “others”) were observed ( Figure 14 b). Forward scatter height (FSC-H) indicated that these “other” particles were not 10-μm PS multiplets. As previously explained, the multiplet population and its corresponding singlet appeared at the same FSC-H. Additionally, forward scatter area (FSC-A) indicated that the “other” particles were ∼ four times smaller than the 10-μm PS singlet ( Figure 16 b).

[0241] Initially, it was believed that these particles were contaminants in the MP stock suspension (e.g., control samples). However, although the control contained ∼6,500 counts / mL of “other” particles (Table 1), the control may not be the main source since the “other” counts actually increased in one sample group (i.e., Sigma-92k). Except for two of the four replicates of SPP-950k at 5 min, the “other” counts decreased to <0.5 of the initial value (i.e., ∼6,500 counts / mL) at 0.5 min and remained relatively constant thereafter. Except for two outliers in the 5-min replicates, a similar trend was also observed for P(2-EHA) Sigma-950k For low molar mass P(2-EHA) Sigma-92k a significant increase in the “other” peak was observed. For example, at the 3-min time point, there was a comparable count of singlets compared to “others”. At the 5-min time point, the “other” particle count was ∼78% more than the singlet (e.g., Table 1 and Figure 15 b). Based on these observations, the “other” particles are unlikely to mainly come from the microplastic stock suspension. Without wishing to be bound by any particular theory, it is believed that the “other” counts that appear are generated by stripping the binder from P(2-EHA) Sigma-92k since its molar mass is too low to form strong cohesive interactions.

[0242] Table 1. Summary of Flow Cytometry Data

[0243]

[0244]

[0245] a,bIn the sum value calculation, the doublets and triplets are multiplied by their respective factors. The "other" counts are not included in the sum value.

[0246] 5.4 Experimental Methods

[0247] 5.4.1 Adhesive-Coated Beads as Substrates for Microplastic Removal

[0248] By adding PAA SPP-950k The used dry molecular sieve (2.0 mm, 10.0 g) was coated with PSA by adding PAA solution (1 mL, 5.0% w / v). The beads were manually shaken (3 shakes per second) for 2 min, oven-dried (120 °C) for 10 min, and cooled to ambient temperature.

[0249] A suspension of PET in water (1.5 mg / mL) was prepared by adding PET (7.5 mg, 300 μm) and DI H2O (5 mL) to an 8-mL vial. The mixture was vortexed for 30 s at the 10 / 10 setting. The binder-coated beads (0.100 mg, ~10 beads) were added to the PS suspension, and the sample was manually shaken (3 shakes per second) for 1 min. The beads were transferred to a separate 8-mL vial and washed by adding 5 mL of DI H2O, manually shaken for 10 s, and the water was removed using a needle and syringe. The beads were dried overnight and then analyzed using a scanning electron microscope (SEM).

[0250] A suspension of PS in water (1.5 mg / mL) was prepared by adding PS latex (300 mg, 2.5 wt%, 90 μm) and DI H2O (5 mL) to an 8-mL vial. The mixture was vortexed for 30 s at the 10 / 10 setting. The binder-coated beads (0.100 mg, ~10 beads) were added to the PS suspension, and the sample was manually shaken (3 shakes per second) for 1 min. The beads were transferred to a separate 8-mL vial and washed by adding 5 mL of DI H2O, manually shaken for 10 s, and the water was removed using a needle and syringe. The beads were dried overnight and then analyzed using a scanning electron microscope (SEM).

[0251] 5.4.2 Comparison of the Performance of Adhesive-Coated Beads and Glass Slides

[0252] Zirconium silicate beads (0.5 mm, 20.0 g) were added to a 40-mL vial and washed by adding 10 mL of acetone and shaking for 30 s, followed by removing the solvent using a needle and syringe. The beads were spread on aluminum foil and oven-dried (120 °C) for 10 min. After cooling to ambient temperature, PAA was added SPP-950k(0.50 mL, 10% w / v), and the beads were shaken manually (3 shakes per second) for 2 min. The beads were dried under high vacuum for 3 h.

[0253] A stock suspension of PS in water (50 mL, 0.38 mg / mL) was prepared by adding PS latex (760 mg, 2.5 wt%, 90 μm) and DI H2O (50 mL) to a 50-mL centrifuge tube. The mixture was vortexed at the 10 / 10 setting for 30 s. The stock solution was vortexed at the 10 / 10 setting for 30 s, then aliquots were taken and stored in the refrigerator after each use.

[0254] To an 8-mL vial containing the PS suspension (3.5 mL, 0.38 mg / mL), adhesive-coated beads (50 mg) were added, and then vortexed at the 10 / 10 setting in duplicate for an appropriate time (i.e., 0.5 min, 1.0 min, and 2 min). The beads were transferred to separate 8-mL vials and washed by adding 5 mL of DI H2O, shaking manually for 10 s, and removing the water using a needle and syringe. The beads were air-dried for 1 h and then analyzed using an optical microscope.

[0255] 5.4.3 Effects of Time, Adhesive Molar Mass, and Microplastic Size on Removal Efficiency

[0256] Two stock suspensions of PS (1 mg / mL) in a 20% EtOH aqueous solution were prepared by adding PS (40.1 mg, 10 μm), deionized water (32 mL), and EtOH (8 mL) to a 50-mL centrifuge tube. The mixture was vortexed at the 10 setting for 30 s and sonicated for 15 min.

[0257] Four types of adhesive-coated beads (PAA SPP-950k , PAA Sigma-450k , PAA P&G-450k and PAA Sigma-92k ) were prepared. Zirconium silicate beads (0.5 mm, 20.0 g) were added to a 20-mL vial and washed by adding 10 mL of acetone and shaking for 30 s, followed by removing the solvent using a needle and syringe. The beads were spread on aluminum foil and oven-dried (120 °C) for 10 min. After cooling to ambient temperature, an adhesive solution (1.0 mL, 5% w / v) was added, and the beads were shaken manually (3 shakes per second) for 2 min. The beads were dried under high vacuum for 3 h.

[0258] For each of the four types of adhesives, four time points (0.5 min, 1 min, 3 min, and 5 min) and four replicates at each time point (i.e., a, b, c, and d) (i.e., 64 samples) were collected. The adhesive-coated beads were added to sixty-four 4-mL vials and labeled accordingly. A colleague manually shook all the "2" and "3" samples, while the researcher manually shook the "1" and "4" samples. The stock solution was manually shaken (3 shakes per second) for 10 s before transferring each aliquot to maintain a homogeneous suspension. Each sample was aliquoted only immediately before the manual shaking cycle.

[0259] PS suspension (1 mL) was added to four 4-mL vials containing adhesive-coated beads using a syringe. After shaking for an appropriate amount of time, the suspension was transferred to 1.5-mL Eppendorf tubes using a needle and syringe and stored in the refrigerator.

[0260] 5.5 Summary

[0261] In summary, it was serendipitously found that the pressure-sensitive adhesive effectively captured micronized rubber in liquid waste containers. This result was confirmed using other microplastics including polystyrene, polyethylene terephthalate, and nylon. Of interest in the preliminary results was the exploration of the microplastic removal efficiency of poly(2-EHA) adhesives in the range of 92 kg / mol - 950 kg / mol coated on zirconium silicate beads. The adhesive with the lowest molar mass, Sigma-92k, controlled the microplastic removal efficiency by removing 81% within 30 s, while the other adhesives removed 50% - 59%. Ultimately, the removal efficiencies of Sigma-92k, P&G-450k, Sigma-450k, and SPP-950k were 99%, 99%, 92%, and 96%, respectively. Although Sigma-92k exhibited the best microplastic removal kinetics, it was suspected that Sigma-92k suffered from adhesive peeling, thereby introducing new microplastics. Although low molar mass improved the microplastic removal kinetics, adhesive peeling may occur due to the lack of cohesion.

[0262] Example 6

[0263] Representative Pressure-Sensitive Adhesives

[0264] Various PSA chemical structures are suitable for the methods and articles disclosed in the present invention. Representative PSA chemical structures and their synthesis methods are shown in Scheme V.

[0265]

[0266] Scheme V. Synthesis of pressure-sensitive adhesives with targeted surface energy parameters using acid-catalyzed esterification.

[0267] Surface energy (γ) plays a key role in the underwater capture of MP. More specifically, when the polarity of the surface energy (γ) between two materials p ) and dispersion (γ d ) component ratio Similarly, a stronger bond is achieved between the PSA and the substrate. (KRUSSScientific. 2021) Although not stated directly, supporting this hypothesis, Tiu, 2019 and Clancy, 2016 showed that adhesives containing benzyl groups, poly(2-ethylhexyl acrylate) adhesives, significantly improved adhesion to underwater steel substrates. The increase in polar components imparted by the incorporated benzyl groups may improve adhesion, thereby It is more comparable between steel and PSA.

[0268] This concept can also be used to improve the interaction between the adhesive and the substrate used to capture MPs (e.g., zirconium silicate), which will most likely reduce adhesive debonding—even for low-molar-mass PSAs (e.g., <400 kg / mol). For example, the esterification approach can be used to synthesize poly(2-ethylhexyl acrylate) modified with other functional groups (e.g., benzyl, perfluoro, and polyethylene oxide).

[0269] In certain embodiments, the PSA comprises a polymer selected from the group consisting of:

[0270]

[0271] Example 7

[0272] Effect of Surfactants on Microplastic Removal

[0273] Further studies also explored the removal of MPs in the presence of surfactants (i.e., sodium lauryl sulfate) at concentrations ranging from 0.01% w / v to 0.1% w / v. The MP removal efficiency was evaluated based on the MP coverage on the slides analyzed using optical microscopy ( Figure 21 a). The results indicate that MP removal is not negatively affected by sodium dodecyl sulfate (SDS). In fact, the addition of surfactant actually increases MP coverage by over 50%. Without wishing to be bound by any particular theory, if SDS does enhance MP removal efficiency, plasticization of the adhesive surface by small surfactant molecules (which improves adhesion) is a potential explanation. This hypothesis can be confirmed by performing the same experiment using a polymeric surfactant (e.g., high molar mass polyvinyl alcohol), which is less likely to act as a plasticizer.

[0274] In this example, a stock dispersion of PS in DI H2O (5 mg / mL) was prepared by adding PS (200 mg, 40 μm) and deionized water (40 mL) to a 50-mL centrifuge tube. The mixture was vortexed for 30 s at the 10 / 10 setting and sonicated for 5 min. Aliquots (2 mL) were transferred to four 8-mL vials while manually shaking (3 shakes per second) for 10 s between aliquot transfers and were subsequently used for the MP removal experiment.

[0275] In a 4-mL vial, sodium dodecyl sulfate (SDS, 20 mg) was dissolved in DI H2O (1.0 mL) to prepare a 2.0% w / v stock solution. Serial dilutions were made to prepare 1.0% (500 μL of the 2.0% solution plus 500 μL of DI H2O) and 0.2% (100 μL of the 1.0% solution plus 400 μL DI H2O). To prepare samples with different concentrations of surfactant (e.g., 0.10% w / v, 0.05% w / v, and 0.01% w / v), 100 μL of the 2.0% w / v, 1.0% w / v, and 0.20% w / v surfactant solutions were added to 2 mL of the MP suspension.

[0276] Prepare P(2-EHA) P&G_780k a 10% w / v solution in THF and used for MP removal. Adhesive droplets (10 μL) were dispensed onto each glass substrate (0.8 mm × 20 mm) using a micropipette ( Figure 22 ). The THF was allowed to evaporate for 2 min under ambient conditions and was then further dried in an oven at 125 °C for 2 min. The slides were cooled to ambient temperature for approximately 5 min.

[0277] To remove the MP, the adhesive-coated slides were dropped into the 8 mL containing the microplastic dispersion and immediately vortexed at the 6 / 10 setting for 1 min. The slides were then washed with deionized water and then allowed to air dry for 20 min. The slides were analyzed by taking optical microscopy images of the center of each spot. See Figure 23

[0278] References

[0279] All publications, patent applications, patents, and other references mentioned in the specification are indicative of the level of skill of those of ordinary skill in the art to which the disclosed subject matter of the invention pertains. All publications, patent applications, patents, and other references are hereby incorporated by reference in their entirety, to the same extent as if each individual publication, patent application, patent, and other reference was specifically and individually indicated to be incorporated by reference. It should be understood that although many patent applications, patents, and other references are mentioned herein, such references do not constitute an admission that any of these documents forms part of the common general knowledge in the art.

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[0332] Although the foregoing subject matter has been described in some detail for purposes of clarity of understanding by way of illustration and example, those skilled in the art will appreciate that certain changes and modifications may be practiced within the scope of the appended claims.

Claims

1. A method for removing microplastic or nanoplastic particles from a medium, the method comprising contacting the microplastic or nanoplastic particles in the medium with an article comprising one or more pressure-sensitive adhesives, wherein the one or more pressure-sensitive adhesives comprise a compound of formula (I) or formula (II): Wherein: Each n is independently an integer from 1 to 10,000; Each R1, R2 and R3, if present, is independently selected from the group consisting of: Wherein: Each m is independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7 and 8; p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7 and 8; u is an integer selected from the group consisting of 1, 2, 3, 4 and 5; v is an integer selected from the group consisting of 1, 2, 3 and 4; w is an integer selected from the group consisting of 1, 2 and 3; Each R4 is independently selected from the group consisting of: H, C1-C8 substituted or unsubstituted branched or straight-chain alkyl, hydroxy, C1-C8 alkoxy, amino, cyano, -CF3, carbonyl, carboxyl, C1-C8 alkynyl, acyl, carbamoyl, halogen, nitro, mercapto and thiol; and R5 is a C3-C 20 branched alkyl group.

2. The method according to claim 1, wherein R1, R2 and R3, if present, are each independently selected from the group consisting of: Where p and q are each independently an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7 and 8.

3. The method according to claim 1, wherein the pressure-sensitive adhesive is made from recycled superabsorbent polymer.

4. The method according to claim 3, wherein the recycled superabsorbent polymer is degraded to poly(acrylic acid); and wherein the poly(acrylic acid) is derivatized to the pressure-sensitive adhesive.

5. The method according to claim 1, wherein the microplastic or nanoplastic particles comprise a material selected from the group consisting of: rubber, polyamide, polyester, poly(ethylene), poly(propylene), polystyrene, cellulose, polyvinyl fluoride, polyvinylidene fluoride, poly(tetrafluoroethylene), polychlorotrifluoroethylene, perfluoroalkoxy alkane, fluorinated ethylene propylene, ethylene tetrafluoroethylene, ethylene chlorotrifluoroethylene, perfluoroelastomer, chlorotrifluoroethylene-vinylidene fluoride FPM / FKM, tetrafluoroethylene-propylene FEPM, perfluoropolyether, perfluorosulfonic acid PFSA, perfluoropolyepoxybutane, and combinations thereof.

6. The method according to claim 5, wherein the microplastic or nanoplastic particles comprise a material selected from the group consisting of: poly(isoprene), poly(ethylene terephthalate), and combinations thereof.

7. The method according to claim 1, wherein the medium is selected from the group consisting of an aqueous medium and an atmospheric medium.

8. The method according to claim 7, wherein the aqueous medium is selected from the group consisting of: wastewater effluent from a wastewater treatment plant, laundry effluent from a commercial laundry facility, laundry effluent from a personal washing machine, and fill water in a washing machine during or after a wash cycle.

9. The method according to claim 7, wherein the atmospheric medium is selected from the group consisting of: indoor air, outdoor air, and emissions, exhaust gases, and / or exhaust fumes from commercial or personal dryers.

10. The method according to any one of claims 1 to 9, the method further comprising removing the microplastic or nanoplastic particles from the one or more pressure-sensitive adhesives.

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