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Showing papers in "Journal of Polymer Science Part A in 2019"



Journal ArticleDOI
TL;DR: In this article, photo-mediated controlled radical polymerizations are evaluated with in situ 1H NMR monitoring to assess their behavior in the dark, and it is observed that Cu-mediated systems undergo long-lived, linear growth during dark periods in organic media.
Abstract: A signature of photo‐mediated controlled polymerizations is the ability to modulate the rate of polymerization by turning the light source ‘on’ and ‘off.’ However, in many reported systems, growth can be reproducibly observed during dark periods. In this study, emerging photo‐mediated controlled radical polymerizations are evaluated with in situ 1H NMR monitoring to assess their behavior in the dark. Interestingly, it is observed that Cu‐mediated systems undergo long‐lived, linear growth during dark periods in organic media.

66 citations



Journal ArticleDOI
TL;DR: In this article, the carbazole scaffold was used for photoinitiators/photosensitizers for both the free-radical polymerization of methacrylates and the cationic polymerisation of epoxides upon visible light exposure using LED@405 nm.
Abstract: In this article, new compounds based on the carbazole scaffold (DMs = DM1 and DM2, constituted by a carbazole unit connected on positions 3 and 6 to a two 4,4 '-dimethoxydiphenylamine groups and differing by the substituent present on the nitrogen heteroatom of the carbazole core) were synthesized and proposed as high-performance visible light photoinitiators/photosensitizers for both the free-radical polymerization of methacrylates and the cationic polymerization of epoxides upon visible light exposure using LED@405 nm. Remarkably, DM2 leads to higher final conversions than DM1. In order to study the photophysical and photochemical properties of the carbazole derivatives, different parameters were taken into account such as the light absorption, the steady-state photolysis, and the fluorescence spectroscopy. Using different techniques such as fluorescence quenching, redox behavior, and cyclic voltammetry, we are able to discuss the photosensitization/photoinitiation reactions providing a full coherent picture of the involved chemical mechanisms. The photosensitization of the carbazole derivatives occurred predominantly via singlet excited states at the rate of the diffusion limit. Upon exposure to laser diode at 405 nm, DMs show high performance in initiating systems for 3D resins. Remarkably, DM2 can also be used in photocomposite synthesis using light-emitting diode conveyor. (c) 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019

52 citations



Journal ArticleDOI
TL;DR: In this article, it was shown that adding periodate, permanganate, or iodate to soy flour improved the strength of soy adhesive bonds in small-scale testing and in plywood shear, especially when tested under wet conditions.
Abstract: To meet newer environmental standards, modified plant proteins have been studied as no‐added formaldehyde wood adhesives for interior applications. Many methods have been developed to increase the wet strength of wood products bonded with soy adhesives. These methods involve modifying the soy in separate steps prior to formulating the adhesive or adding a polymerizable co‐reactant to the soy. We show that adding periodate, permanganate, or iodate to soy flour improved the strength of soy adhesive bonds in small‐scale testing and in plywood shear, especially when tested under wet conditions. Periodate improved the bond strength of other plant materials (lupine, canola, and cottonseed) but none of these produced as high of a wet strength as the soy flour. We investigated other oxidants with plant proteins. Permanganate was quite effective and iodate was somewhat effective, whereas nitric acid, chlorate, perchlorate, and bromate were not effective in increasing wet strength. The available data are consistent with oxidation of the carbohydrate–protein mixture in plant flours to provide adhesives with increased wet strength in wood bonds. This mechanism was also supported by the improved wet strength with the addition of dialdehydes (glyoxal and glutaraldehyde). The purified soy protein also gave strength improvement with periodate. Published 2019. This article is a U.S. Government work and is in the public domain in the USA. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1017–1023

49 citations




Journal ArticleDOI
TL;DR: Entropy-driven ROMP (ED•ROMP) as discussed by the authors involves polymerization of olefin-containing macrocyclic monomers under entropically favorable conditions, where the sequence of atoms in the cyclic monomer is preserved within the polymer repeating units, allowing for facile preparation of sequence defined polymers.
Abstract: Entropy‐driven ROMP (ED‐ROMP) involves polymerization of olefin‐containing macrocyclic monomers under entropically favorable conditions. Macrocycles can be prepared from a variety of interesting molecules which, when polymerized, impart unique functionality to the resulting polymer backbone such as degradable linkages, biological moieties, crystallizable groups, or supramolecular hosts. In addition, the sequence of atoms in the cyclic monomer is preserved within the polymer repeating units, allowing for facile preparation of sequence‐defined polymers. In this review article, we consider how the mechanism of ROMP applies to ED polymerizations, how olefinic macrocycles are synthesized, and how polymerization conditions can be tuned to maximize conversion. Recent works in the past 10 years are highlighted, with emphasis on methods which can be employed to achieve fast polymerization kinetics and/or selective head‐to‐tail regiochemistry, thus improving polymerization control. ED‐ROMP, with its unique capability to produce polymers with well‐defined polymer backbone microstructure, represents an essential complement to other, well‐established, metathesis methodologies such as ROMP. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1621–1634

40 citations


Journal ArticleDOI
TL;DR: In this article, the effect of PLGA block and PEG chain molecular weights (MWs) on the gelling temperature of polymer aqueous solution (20% w/w) is described.
Abstract: Thermoresponsive, biodegradable polymeric hydrogel networks are used widely in medicinal applications. Poly(D,L-lactic acid-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(D,L-lactic acidco-glycolic acid) (PLGA-PEG-PLGA) triblock copolymers exhibit a sol–gel transition upon heating. The effect of PLGA block and PEG chain molecular weights (MWs) on the gelling temperature of polymer aqueous solution (20% w/w) is described. All polymer solutions convert into a hard gel within 2 C of the gelling temperature. The release properties of the gels were displayed using paracetamol as a representative drug. A linear relation is described between the gelling temperature and PLGA block MW. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 35–39

38 citations


Journal ArticleDOI
TL;DR: An in situ forming surgical glue based on photocrosslinkable HA, providing tunable mechanical properties and firm tissue adhesion under wet and dynamic conditions, suggests that it may have great promise as a tissue adhesive.
Abstract: Hyaluronic acid (HA), a naturally occurring linear polysaccharide, has been widely used as a key biomaterial in a range of cosmetic and therapeutic applications. Its excellent biocompatibility and bio-functions related to tissue regeneration encourage the development of HA-based hydrogels to expand its applications. This study details an in situ forming surgical glue based on photocrosslinkable HA, providing tunable mechanical properties and firm tissue adhesion under wet and dynamic conditions. Depending on the degree of photocrosslinkable methacrylate groups in HA polymer chains, the mechanical properties of hyaluronate methacrylate (HAMA) hydrogels prepared by UV photocrosslinking was improved. Ex vivo adhesion tests revealed that HAMA hydrogels exhibited 3-fold higher shear adhesive strength compared to gelatin methacryloyl hydrogels and achieved firm adherence to the porcine skin tissue for several weeks. The high adhesive strength of HAMA hydrogels, under dry and wet conditions, suggests that it may have great promise as a tissue adhesive. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 522–530

Journal ArticleDOI
TL;DR: In this paper, the authors describe advances in the area of cyclic polymer synthesis, with a particular focus on ringexpansion metathesis polymerization, and discuss methods for characterizing cyclic polymers and assessing their purity.
Abstract: Cyclic polymers have drawn considerable interest for their peculiar physical properties in comparison to linear polymers, despite their equivalent compositions. Synthetically, cyclic polymers can be accessed through either macrocyclic ring‐closure or by ring‐expansion polymerization, but the main challenge with either method is the production of highly pure cyclic polymer samples. This highlight describes advances in the area of cyclic polymer synthesis, with a particular focus on ring‐expansion metathesis polymerization. Methods for characterizing cyclic polymers and assessing their purity are also discussed in order to emphasize the need for additional robust and reliable methods for synthesizing and studying topologically complex macromolecules. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 228–242

Journal ArticleDOI
TL;DR: Inam et al. as mentioned in this paper studied the effect of size and shape on the antimicrobial activity of quaternized nanoparticles and found that size and shapes affect the effectiveness of nanoparticles.
Abstract: This is the peer reviewed version of the following article: Inam, M. , Foster, J. C., Gao, J. , Hong, Y. , Du, J. , Dove, A. P. and O'Reilly, R. K. (2018), Size and shape affects the antimicrobial activity of quaternized nanoparticles. J. Polym. Sci. Part A: Polym. Chem.. . doi:10.1002/pola.29195, which has been published in final form at https://doi.org/10.1002/pola.29195. This article may be used for noncommercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Journal ArticleDOI
TL;DR: This protocol established a practical protocol to address scalability problems in the photo‐RAFT SUMI processes and offers the process with large quantity, excellent isolated yields, and short production time.
Abstract: As one of the emerging techniques for preparing discrete oligomers, the photo‐RAFT single unit monomer insertion (SUMI) process has shown its uniqueness and superiority in the control of both monomer sequence and stereochemistry. However, current precision polymer synthesis techniques are still burdened by the scalability challenges, such as low reaction yields, small product quantities, and long production times. Herein, we successfully established a practical protocol to address scalability problems in the photo‐RAFT SUMI processes. A series of discrete oligomers containing up to five monomer units were synthesized in batch and flow reactors by sequential and alternating SUMI of two monomers into a trithiocarbonate RAFT agent under mild reaction conditions and purified by automated flash chromatography. This protocol offers the process with large quantity (grams scale), excellent isolated yields (82%–95% for each step and 59% for five iterations), and short production time (several days for a pentamer). © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1947–1955

Journal ArticleDOI
TL;DR: In this paper, it was demonstrated that the degree of livingness (chain-end fidelity) in RAFT polymerization for a given degree of polymerization can be markedly increased in miniemulsion polymerization relative to the corresponding homogeneous bulk system.
Abstract: It is demonstrated that the degree of livingness (chain‐end fidelity) in RAFT polymerization for a given degree of polymerization can be markedly increased in miniemulsion polymerization relative to the corresponding homogeneous bulk system. Polymerization of styrene was conducted using a poly(methyl methacrylate) benzodithioate as macroRAFT agent in both miniemulsion and bulk. The substantially higher polymerization rate in miniemulsion, which is attributed to the segregation effect (compartmentalization) causing a reduction in the rate of bimolecular termination, makes it possible to reach a given degree of polymerization in a significantly shorter time than in the corresponding bulk system. As a consequence, fewer initiating radicals are required throughout the polymerization, leading to higher livingness in the more rapid miniemulsion system. It is demonstrated how this approach facilitates synthesis of high‐molecular‐weight block copolymers comprising slowly propagating monomers such as styrene and methacrylates. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1938–1946

Journal ArticleDOI
TL;DR: The use of dormant species has opened a new era in precision polymerization and has changed the concept of living polymerization as discussed by the authors, which is effective in controlling all chain growth polymerizations, including radical, cationic, anionic, coordination, ring-opening metathesis, and ring opening polymerizations.
Abstract: The use of dormant species has opened a new era in precision polymerization and has changed the concept of living polymerization. The dormant species can be exchanged into the active species via reversible termination or via reversible chain transfer. Professor Mitsuo Sawamoto has greatly contributed to the establishment of the concepts of living cationic and radical polymerizations based on the reversible activation of dormant species. This highlight, dedicated to Professor Sawamoto on his retirement from Kyoto University, provides an overview of reversible or degenerative chain‐transfer (DT) processes, which are effective in controlling all chain‐growth polymerizations, including radical, cationic, anionic, coordination, ring‐opening metathesis, and ring‐opening polymerizations. In addition, structures with novel sequences accessible only by a combination of different propagating species with a common DT agent are reviewed. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 243–254



Journal ArticleDOI
TL;DR: Xiao et al. as mentioned in this paper presented a study that was supported by National Natural Science Foundation of China (grant no. 51203123), the National Key Research and Development Program (No. 2016YFA0101102), and the Australian Research Council Future Fellowship (FT170100301).
Abstract: This study was supported by National Natural Science Foundation of China (grant no. 51203123), the National Key Research and Development Program of China (no. 2016YFA0101102). P. Xiao acknowledges funding from the Australian Research Council Future Fellowship (FT170100301).






Journal ArticleDOI
TL;DR: In this paper, two enzymatic-mediated and one syringe pump-driven Fenton-RAFT polymerization processes are presented, in which the initiating radicals are carefully and gradually dosed into the reaction solution.
Abstract: This study demonstrates that the gradual and slow production of initiating radicals (i.e., hydroxyl radicals here) is the key point for the synthesis of ultra-high molecular weight (UHMW) polymers via controlled radical polymerization. Hydrogen peroxide (H2O2) and ferrous iron (Fe2+) react via Fenton redox chemistry to initiate RAFT polymerization. This work presents two enzymatic-mediated (i.e., Bio-Fenton-RAFT and Semi Bio-Fenton-RAFT) and one syringe pump-driven Fenton-RAFT polymerization processes in which the initiating radicals are carefully and gradually dosed into the reaction solution. The “livingness” of the synthesized UHMW polymers is demonstrated by chain extension and aminolysis experiments. Zimm plots obtained from static light scattering (SLS) technique are used to characterize the UHMW polymers. This Fenton-RAFT polymerization provides access to polymers of unprecedented UHMW (Mw ~ 20 × 106 g mol−1) with potential in diverse applications. The UHMW polymers made via the controlled Fenton-RAFT polymerization by using a syringe pump shows that it is possible to produce such materials through an easy-to-set up and scalable process. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019.

Journal ArticleDOI
TL;DR: In this article, a polyoxometalate (POM)/polymer hybrid composites were prepared by photopolymerization under mild conditions for suitable photocatalytic processes.
Abstract: New polyoxometalate (POM)/polymer hybrid composites were prepared by photopolymerization under mild conditions for suitable photocatalytic processes. Polyoxometalates were incorporated in special photosensitive resins, which were photopolymerized under visible light to obtain new materials with photocatalytic activity for dye removal. The synthesized composites were characterized by real-time FT-IR, and the photocatalytic ability was investigated on Eosin-Y removal using photolysis under near


Journal ArticleDOI
TL;DR: In this paper, a novel one-handed helical poly bearing L−hydroxyproline pendants (poly(P)) was synthesized as an eco-friendly polymer-supported catalyst for asymmetric reactions.
Abstract: A novel one‐handed helical poly(phenylacetylene) bearing L‐hydroxyproline pendants (poly(PA‐P)) was synthesized as an eco‐friendly polymer‐supported catalyst for asymmetric reactions. The helical poly(PA‐P) catalyzed the asymmetric aldol reactions of cyclohexanone with p‐nitrobenzaldehyde, and showed good recyclability and higher enantiomeric excess (ee) in aqueous medias than that in organic medias. The one‐handed helicity of poly(PA‐P) was clearly affected by the water content in the aqueous media. The helical poly(PA‐P) showed the higher enantioselectivity (ee = 99%) than its monomer PA‐P (ee = 54%) in THF/H₂O (H₂O vol % = 25.0 vol %). After the one‐handed helical structure of poly(PA‐P) was destroyed by grinding treatment, the ee of the reaction clearly decreased from 99 to 49%. These indicate that the one‐handed helical structure of poly(PA‐P) played an important role in the high enantioselectivity of the asymmetric aldol reactions in the aqueous media. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1024–1031


Journal ArticleDOI
TL;DR: In this paper, the outcome of the statistical terpolymerization of butadiene, styrene and Diphenylethylene (DPE) is reported, a one-pot, one-shot, commercially scalable copolymer.
Abstract: Diphenylethylene (DPE) is a monomer which has attracted significant interest from academia and industry both in terms of copolymerization kinetics and for the potential to extend and tune the range of glass transition temperatures accessible for DPE-containing copolymers. DPE can undergo (co)polymerization with a variety of other monomers by living anionic polymerization but is incapable of forming a homopolymer due to steric hindrance. DPE, being a sterically bulky monomer, results in dramatic increases in the glass transition temperature (Tg) of resulting copolymers, with a perfectly alternating copolymer of styrene and DPE having a Tg of approximately 180 C. Herein we report for the first time, the outcome of the statistical terpolymerization of butadiene, styrene and DPE – a one-pot, one-shot, commercially-scalable