Thermal paper presents widely recognized health hazards due to its formulations containing bisphenol A (BPA) and bisphenol S (BPS) as color developers with limited research on safer alternatives. Here, we introduce sustainable thermal paper formulations built with functionalized lignin polymers and lignin-derived esters, combined with a sensitizer derived from xylan. Light-colored lignin polymer was obtained via sequential aldehyde-assisted fractionation, which reduced chromophore concentration through multiple extraction cycles. Good performance was achieved with polymeric lignin (color density at 120 degrees C approximate to 0.8 to 1.1) when combined with xylan-derived diformylxylose (DFX), each of which is produced directly by simple biomass fractionation. Coatings remained stable for over a year under ambient conditions. Last, lignin-based developers showed estrogenic activity that was two to three orders of magnitude lower than BPA and one to two orders of magnitude lower than BPS, while the DFX sensitizer showed no signs of estrogenic activity or toxicity to bacteria or algae.

Deploying agrochemicals as nanoparticle-based formulations not only provides opportunities to tune release kinetics, prevent premature degradation, increase shelf life, and reduce loss of active ingredient but also can enable the design of systems that can interact with or respond to soil and/or plants in a specific manner, which provides further opportunities to refine the delivery of agrochemicals. This article presents tripolyphosphate (TPP)-cross-linked lignin-based nanofertilizers that are designed to disintegrate and release phosphorus upon exposure to acid phosphatase, which is an enzyme that is upregulated as part of the phosphate starvation response of plants. In model experiments, it was shown that phosphorus release from the lignin-TPP nanoparticles was triggered by acid phosphatase, dependent on the enzymatic activity, and accompanied by the simultaneous disintegration of the nanoparticles. Experiments with the model plant Arabidopsis thaliana showed that lignin-TPP nanoparticles are an efficient phosphorus source for plants, suppressing the typical growth inhibition and activation of the molecular mechanisms triggered by phosphate deficiency. These experiments underline the potential of lignin-TPP nanoparticles in providing readily accessible phosphate for plants during growth and development, which represents a step forward toward nanofertilizers that are able to release their payload on demand in a plant-growth-synchronized manner.

Polymer brushes composed of densely grafted end-tethered polymer chains are often used in the solvent-swollen state, for example, as boundary lubricants or non-fouling surface coatings. For a given polymer brush in a specific solvent system, grafting density and polymer molecular weight are the principal structural parameters to tune swelling behavior. This report presents substrate surface chemistry as an additional parameter to control the swelling properties of polymer brushes generated via surface-initiated atom transfer radical polymerization (SI-ATRP). To uncover the impact of substrate surface chemistry, hydrophobic poly(tert-butyl methacrylate) (PtBMA), and hydrophilic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes were grafted from substrates, which presented dipeptide and alkyl spacer tethered ATRP initiators and displayed water contact angles ranging from 48°-78°. Swelling of PtBMA brushes in a good solvent (THF) was found to be governed by polymer-solvent interactions, and substrate effects are negligible. In mixed solvents with a minority component that is a non-solvent for the polymer, in contrast, substrate surface chemistry does influence swelling, and was found to correlate with the polarity of the dipeptide ATRP initiator presenting substrate. Results of the analysis of the swelling behavior of hydrophilic brushes in water also point toward an impact of substrate surface chemistry.

Abstract Surface-initiated polymerizations generate thin films (“brushes”) consisting of polymer chains that are anchored with one chain end to a solid surface. As they are conducted from initiator-modified solid substrates, these polymerizations allow for unidirectional chain growth and enforce a stretched chain conformation. Using acrylonitrile as an example of a monomer with a dipolar side-chain functional group, this study finds that surface-initiated polymerization not only impacts the alignment and conformation of the polymer main chain but can also influence the orientation of side-chain functional groups. Surface-initiated polymerization of acrylonitrile is found to result in polyacrylonitrile (PAN) brushes that display spontaneous pyro- and piezoelectric behavior. As these properties are not observed in spin-cast PAN films, this indicates that surface-initiated growth of PAN enforces an overall parallel orientation of the dipolar nitrile side-chain functional groups. This is supported by polarized FTIR spectroscopy and NEXAFS experiments, which suggest an overall nonisotropic orientation of nitrile groups in the PAN brush, whereas the nitrile groups in the spin-cast PAN film are more isotropically oriented. Pyro- and piezoelectric polymers are attractive for use in sensors, actuators, and energy-harvesting devices but typically require electrical poling, mechanical stretching, or electrospinning to promote the alignment of molecular dipoles and enhance piezo- and pyroelectric properties. The ability to prepare thin polymer films that display spontaneous pyro- and piezoelectric behavior is significant as it renders these postprocessing steps unnecessary.

This paper describes the synthesis of supramolecular polymer brushes via surface-initiated polymerization from adamantane-functionalized initiators that are noncovalently bound to β-cyclodextrin- or cucurbit[7]uril-modified substrates. Surface-initiated atom transfer radical polymerization in aqueous media allowed the growth of various hydrophilic polymer brushes with film thicknesses of up to 40 nm from β-cyclodextrin functionalized surfaces. The adamantane moiety not only forms a host-guest complex with β-cyclodextrin, but also with cucurbit[7]uril, which provides opportunities to study the effect of the binding strength of these supramolecular motifs on the film thickness and grafting density of the resulting polymer brushes. Comparison of supramolecular polymer brushes grown from β-cyclodextrin and cucurbit[7]uril-based noncovalent initiators reveals differences in grafting density that are much smaller than expected based on the differences in the solution binding constant of the corresponding host-guest complexes. Both the β-cyclodextrin as well as the cucurbit[7]uril-anchored supramolecular brushes were remarkably robust toward detachment of the polymer grafts. These observations are attributed to the fact that the rates of formation and dissociation of the host-guest complexes are much faster as compared to diffusion of free, detached polymer chains through the polymer brush film. As a result, the surface-grafted polymer brush presents a steric barrier that prevents detachment of individual chains, and also allows surface-initiated polymerization from substrates to which initiators are bound via putatively weak β-cyclodextrin-based host-guest complexes.

The current use of fertilizers is inefficient and not sustainable. The majority of the fertilizer applied does not reach the targeted crop but is lost in the water bodies and into the atmosphere, with harmful impact on the environment. To enhance the efficiency and sustainability of current agricultural practices, it is essential to address two complementary challenges. First, nutrient delivery methods must be refined to maximize plant uptake. Second, the recovery of nutrients from wastewater and other waste streams should be improved to enhance the recycling of nitrogen and phosphorous and reduce environmental pollution. Biodegradable polymers hold great promise for the development of technological solutions toward more sustainable agricultural practices. This review covers the application of biodegradable polymers in both aspects of the nutrient cycle: nutrient delivery to plants through slow- and controlled-release fertilizers, and nutrient recovery from wastewater using membrane separation, adsorbent composites, and coagulants/flocculants. The most promising materials are highlighted for both approaches, identifying the research gaps and discussing potential future directions in this highly significant field.

Polymer brushes engineered to "specifically capture" and "release on demand" analytes such as dyes, proteins, and cells find biomedical applications ranging from protein immobilization to cell death. Utilizing a disulfide-linker-containing monomer as a building block enables the fabrication of a redox-responsive polymer brush platform with the "catch and release" attribute. Herein, thiol-reactive redox-responsive polymer brushes are fabricated using a pyridyl disulfide-based monomer, and their postpolymerization functionalization is demonstrated via thiol-disulfide exchange reaction with thiol-containing dyes, (bio)molecules, and cell adhesive ligands. After establishing reversible conjugation using a fluorescent dye and other model compounds, copolymer brushes postmodified with thiol-containing mannose demonstrated selective immobilization of concanavalin A in the presence of peanut agglutinin. In addition, a thiolated RGD peptide was conjugated to the side chain of polymer brushes to facilitate cell adhesion, followed by on-demand harvesting. To enable localized drug delivery to surface-adhered cells, orthogonal chain end and side chain functionalization using the thiol-Michael addition and thiol-disulfide exchange reaction, respectively, was used to conjugate the cell adhesive RGD peptide and the anticancer drug doxorubicin (DOX). On-demand DOX release and internalization by surface-bound cancer cells were demonstrated via cleavage of disulfide linkages in the presence of a reducing agent. This approach may provide an attractive methodology to deliver therapeutic agents precisely to specific cells.

Polycarbonate polymers find widespread use for a variety of applications. Driven by the need to transition away from fossil-based resources, there is increasing interest in exploring bio-based monomers for the synthesis of polycarbonates. One interesting class of molecules that can be isolated from a variety of biological resources, including lignin, are hydroxycinnamic acids. This paper reports the synthesis of a library of aromatic diols using p-coumaric acid, ferulic acid, and sinapic acid as starting materials. Using dimethyl carbonate, these diols can be polymerized to generate a variety of semi-aromatic polycarbonate homo- and copolymers. These polycarbonates can be depolymerized via an organocatalyzed process to afford the starting diols in essentially quantitative yield. The monomers obtained from this depolymerization process could subsequently be repolymerized, with no purification needed, to regenerate the original polymer with essentially identical molecular weight, providing a pathway to the chemical recycling of these materials.

Upon exposure to a good solvent, polymer brushes prepared via surface-initiated polymerization can undergo degrafting via cleavage of bonds that anchor the polymer tethers to the underlying substrate. As polymer brushes are often used in a solvent swollen state, this has implications for the longevity of these polymer coatings. Improving the fundamental understanding of this process is thus also of practical importance. It is believed that degrafting is the consequence of tension amplification at the bonds that anchor the polymer grafts, which is driven by swelling of the polymer brush film. Taking advantage of the sensitivity of the swelling behavior of poly(3-sulfopropyl methacrylate) (PSPMA) brushes toward changes in ionic strength, this study has investigated the degrafting behavior of these brushes in aqueous media at different LiCl and NaCl concentrations. The aim of these experiments was to investigate whether the rate constant of the degrafting process was correlated with the swelling ratio of the PSPMA brushes. The experiments show that in aqueous LiCl solutions, the initial rate constant of the degrafting process is correlated with the swelling ratio of the PSPMA brush. This observation represents a first example of the correlation between these two parameters for hydrophilic polymer brushes in aqueous media and supports the idea that degrafting is a mechanochemical process driven by a swelling-induced tension at the polymer-substrate interface.

ADVERTISEMENT RETURN TO ARTICLES ASAPEditorialNEXTACS Polymers Au Recognizes 2023 Rising Stars in PolymersArthi Jayaraman*Arthi Jayaraman*Email: [email protected]More by Arthi Jayaramanhttps://orcid.org/0000-0002-5295-4581 and Harm-Anton Klok*Harm-Anton Klok*Email: [email protected]More by Harm-Anton Klokhttps://orcid.org/0000-0003-3365-6543Cite this: ACS Polym. Au 2024, XXXX, XXX, XXX-XXXPublication Date (Web):February 1, 2024Publication History Received17 January 2024Published online1 February 2024https://doi.org/10.1021/acspolymersau.4c00003© 2024 American Chemical Society. This publication is licensed under CC-BY-NC-ND 4.0. License Summary*You are free to share (copy and redistribute) this article in any medium or format within the parameters below:Creative Commons (CC): This is a Creative Commons license.Attribution (BY): Credit must be given to the creator.Non-Commercial (NC): Only non-commercial uses of the work are permitted. No Derivatives (ND): Derivative works may be created for non-commercial purposes, but sharing is prohibited. View full license*DisclaimerThis summary highlights only some of the key features and terms of the actual license. It is not a license and has no legal value. Carefully review the actual license before using these materials. This publication is Open Access under the license indicated. Learn MoreArticle Views-Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (14 MB) Get e-AlertscloseSUBJECTS:Biomaterials,Chemical engineering and industrial chemistry,Materials,Polymer science,Polymers Get e-Alerts

The preparation of polymer gels via cross-linking of four-arm star-shaped poly(ethylene glycol) (Tetra-PEG) precursors is an attractive strategy to prepare networks with relatively well-defined topologies. Typically, Tetra-PEG gels are obtained by cross-linking heterocomplementary reactive Tetra-PEG precursors. This study, in contrast, explores the cross-linking of self-reactive, thiol-end functional Tetra-PEG macromers to form disulfide-cross-linked gels. The structure of the disulfide-cross-linked Tetra-PEG gels was studied with multiple-quantum NMR (MQ-NMR) spectroscopy and small-angle neutron scattering (SANS) experiments. In line with earlier simulation studies, these experiments showed a strong dependence of the relative fractions of the different network connectivities on the concentration of the thiol-end functional Tetra-PEG macromer that was used for the synthesis of the networks. Disulfide-cross-linked Tetra-PEG gels prepared at macromer concentrations below the overlap concentration (c = 0.66c*) primarily feature defect connectivity motifs, such as primary loops and dangling ends. For networks prepared at macromer concentrations above the overlap concentration, the fraction of single-link connectivities was found to be similar to that in amide-cross-linked Tetra-PEG gels obtained by heterocomplementary cross-linking of N-hydroxysuccinimide ester and amine functional Tetra-PEG macromers. Since disulfide bonds are susceptible to reductive cleavage, these disulfide-cross-linked gels are of interest, e.g., as reduction-sensitive hydrogels for a variety of biomedical applications.

Polyelectrolyte brushes are responsive to salt in the environment, and this has found broad applications in antifouling, biolubrication, and drug delivery. Salt primarily influences the conformation of the polyelectrolytes through ion adsorption. While ion adsorption is typically associated with electrostatic interactions, our research reveals that in multivalent ion solutions, it also enhances nonelectrostatic interactions by bringing distant polyelectrolyte segments closer together. The finding is based on a comparative study between theoretical, simulation, and experimental data for monovalent, divalent, and trivalent cation solutions of sodium poly(styrenesulfonate) (PSS) and potassium poly(3-sulfopropyl methacrylate) (PSPMA) brushes. By incorporating an apparent Flory-Huggins parameter that is linearly dependent on the extent of ion adsorption, we developed a theoretical model for polyelectrolyte brushes that predicts brush heights in good agreement with experimental and simulation data. This work provides three major contributions to our understanding of polyelectrolyte brushes. (a) The theoretical framework reveals that while electrostatic interactions primarily drive the contraction of short-chain brushes (approximately 50 monomers), nonelectrostatic interactions arising from ion adsorption induce the collapse of long-chain brushes (approximately 500 monomers) in multivalent ion solutions. (b) Traditional scaling theory is applied only to long polymer chains in monovalent cation systems. Our modified framework broadens the scope to include both short and long chains in both monovalent and multivalent systems, while most of the traditional scaling theory can only be applied to long-chain systems. (c) We provided a comprehensive quantitative examination of the inter- and intrachain cross-links.

Amino acid-based poly(ester urea)s are an attractive class of polymers that are of interest for a variety of biomedical applications. Generally, amino acid-based poly(ester urea)s are prepared by polymerization of diamines, which are obtained from the corresponding amino acids and aliphatic diols. This article presents an alternative synthetic strategy that uses diamine monomers obtained from aromatic, 4-hydroxycinnamic acid-derived diols. A library of structurally related diamine monomers has been prepared by coupling l-leucine to 4-hydroxycinnamic acid-based diols that incorporate alkyl spacers of different lengths. The exploration of 4-hydroxycinnamic acid as a building block is interesting as it can be obtained from various biological resources, such as for example lignin, and thus provides an opportunity to take advantage of (under-utilized) bio-based renewables for the design of new polymer materials. These diamine monomers can be copolymerized in a solvent-free, one-pot, two-step process using dimethyl carbonate as an environmentally sustainable reagent to afford amino acid-based aromatic poly(ester urea) homo- and copolymers with thermal properties that can be tuned by varying the chemical structure of the diamine monomer, or via copolymerization of two different monomers.

Ought to their bioinert properties and facile synthesis, poly[(oligoethylene glycol)methacrylate]s (POEGMAs) have been raised as attractive alternatives to poly(ethylene glycols) (PEGs) in an array of (bio)material applications, especially when they are applied as polymer brush coatings. However, commercially available OEG-methacrylate (macro)monomers feature a broad distribution of OEG lengths, thus generating structurally polydisperse POEGMAs when polymerized through reversible deactivation radical polymerization. Here, we demonstrate that the interfacial physicochemical properties of POEGMA brushes are significantly affected by their structural dispersity, i.e., the degree of heterogeneity in the length of side OEG segments. POEGMA brushes synthesized from discrete (macro)monomers obtained through chromatographic purification of commercial mixtures show increased hydration and reduced adhesion when compared to their structurally polydisperse analogues. The observed alteration of interfacial properties is directly linked to the presence of monodisperse OEG side chains, which hamper intramolecular and intermolecular hydrophobic interactions while simultaneously promoting the association of water molecules. These phenomena provide structurally homogeneous POEGMA brushes with a more lubricious and protein repellent character with respect to their heterogeneous counterparts. More generally, in contrast to what has been assumed until now, the properties of POEGMA brushes cannot be anticipated while ruling out the effect of dispersity by (macro)monomer feeds. Simultaneously, side chain dispersity of POEGMAs emerges as a critical parameter for determining the interfacial characteristics of brushes.

Piezo- and pyroelectric materials are of interest, for example, for energy harvesting applications, for the development of tactile sensors, as well as neuromorphic computing. This study reports the observation of pyro- and piezoelectricity in thin surface-attached polymer brushes containing zwitterionic and electrolytic side groups that are prepared via surface-initiated polymerization. The pyro- and piezoelectric properties of the surface-grafted polyelectrolyte brushes are found to sensitively depend on and can be tuned by variation of the counterion. The observed piezo- and pyroelectric properties reflect the structural complexity of polymer brushes, and are attributed to a complex interplay of the non-uniform segment density within these films, together with a non-uniform distribution of counterions and specific ion effects. The fabrication of thin pyroelectric films by surface-initiated polymerization is an important addition to the existing strategies toward such materials. Surface-initiated polymerization, in particular, allows for facile grafting of polar thin polymer films from a wide range of substrates via a straightforward two-step protocol that obviates the need for multistep laborious synthetic procedures or thin film deposition protocols. The ability to produce polymer brushes with piezo- and pyroelectric properties opens up new avenues of application of these materials, for example, in energy harvesting or biosensing.

Polymer brushes have been theoretically described, their behavior under diverse conditions has been modeled, and their preparation via surface-initiated polymerizations (SIPs) has been progressively refined. However, despite three decades of research endeavors by chemists and materials scientists, an array of challenges and questions characterizing the synthesis, characterization, and understating of polymer brushes remains and motivates this Perspective. How do the main structural parameters of polymer brushes link to their unique properties? Can we synthesize multifunctional brushes in a more practical and scalable manner? Can we successfully overcome the intrinsic challenges that enable their comprehensive characterization? While being closer than ever to the translation of polymer brushes into technologically relevant materials, we have tried to answer these questions by simultaneously outlining the status of research in this subfield of polymer science and the evolving perspectives in their synthesis and characterization.

Polymer brushes are densely grafted, chain end-tethered assemblies of polymers that can be produced via surface-initiated polymerization. Typically, this is accomplished using initiators or chain transfer agents that are covalently attached to the substrate. This manuscript reports an alternative route towards polymer brushes, which involves the use of non-covalent cucurbit[7]uril-adamantane host-guest interactions to surface-immobilize initiators for atom transfer radical polymerization. These non-covalent initiators can be used for the surface-initiated atom transfer radical polymerization of a variety of water-soluble methacrylate monomers to generate supramolecular polymer brushes with film thicknesses of more than 100 nm. The non-covalent nature of the initiator also allows facile access to patterned polymer brushes, which can be produced in straightforward fashion by drop-casting a solution of the initiator-modified guest molecules onto a substrate that presents the cucurbit[7]uril host.

A series of 3 homologous surface-anchored initiators for atom transfer radical polymerization has been used to graft linear, Y- and Ψ-shaped poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(methyl methacrylate) (PMMA) brushes from silicon surfaces. The film thicknesses of these architecturally different polymer brushes could be tuned both by controlling the polymerization time, as well as (as was shown for the polymerization of 2-(dimethylamino)ethyl methacrylate) by changing the monomer concentration. The library of linear, Y- and Ψ-shaped PDMAEMA and PMMA brushes was used to investigate the possible impact of polymer architecture on the swelling properties as well as the degrafting behavior of these surface-grown polymer films. The swelling of the PDMAEMA and PMMA brushes in PBS, respectively, acetone as a solvent was studied by ellipsometry. These experiments revealed a smaller swelling ratio for Y-shaped polymer brushes, as compared to linear analogues of comparable dry film thickness. Degrafting experiments were conducted with linear, Y- and Ψ-shaped PDMAEMA brushes in PBS. These experiments revealed a 2-fold, respectively, 3-fold increase in the initial rate constant of degrafting for the Y- and Ψ-shaped PDMAEMA brushes as compared to the linear analogues.

AbstractAnion‐exchange membrane fuel cells (AEMFCs) are a promising, next‐generation fuel cell technology. AEMFCs require highly conductive and robust anion‐exchange membranes (AEMs), which are challenging to develop due to the tradeoff between conductivity and water uptake. Here we report a method to prepare high‐molecular‐weight branched poly(aryl piperidinium) AEMs. We show that branching reduces water uptake, leading to improved dimensional stability. The optimized membrane, b‐PTP‐2.5, exhibits simultaneously high OH− conductivity (>145 mS cm−1 at 80 °C), high mechanical strength and dimensional stability, good processability, and excellent alkaline stability (>1500 h) in 1 M KOH at 80 °C. AEMFCs based on b‐PTP‐2.5 reached peak power densities of 2.3 W cm−2 in H2−O2 and 1.3 W cm−2 in H2‐air at 80 °C. The AEMFCs can run stably under a constant current of 0.2 A cm−2 over 500 h, during which the b‐PTP‐2.5 membrane remains stable.

ADVERTISEMENT RETURN TO ISSUEEditorialNEXTACS Polymers Au's Grand Challenges in Polymer ScienceArthi Jayaraman*Arthi Jayaraman*Email: [email protected]More by Arthi Jayaramanhttps://orcid.org/0000-0002-5295-4581 and Harm-Anton Klok*Harm-Anton Klok*Email: [email protected]More by Harm-Anton Klokhttps://orcid.org/0000-0003-3365-6543Cite this: ACS Polym. Au 2023, 3, 1, 1–4Publication Date (Web):February 8, 2023Publication History Received9 January 2023Published online8 February 2023Published inissue 8 February 2023https://doi.org/10.1021/acspolymersau.3c00001Copyright © 2023 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceCC: Creative CommonsBY: Credit must be given to the creatorNC: Only noncommercial uses of the work are permittedND: No derivatives or adaptations of the work are permittedArticle Views650Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-AlertsSUBJECTS:Anionic polymerization,Charge transport,Machine learning,Polymer science,Polymers Get e-Alerts