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Ryosuke Kanto

Bio: Ryosuke Kanto is an academic researcher from Yamagata University. The author has contributed to research in topics: Chain transfer & Cationic polymerization. The author has an hindex of 4, co-authored 4 publications receiving 28 citations.

Papers
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Journal ArticleDOI
08 Mar 2019-Langmuir
TL;DR: A series of anionic, zwitterionic, and cationic lysine-based block copolymers with a thermoresponsive segment were synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization of N-acryloyl- N-carbobenzoxy-l-lysine, which contains a carboxylic acid and a protected amine-functionality in the monomer unit.
Abstract: A series of anionic, zwitterionic, and cationic lysine-based block copolymers with a thermoresponsive segment were synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization of N-acryloyl- N-carbobenzoxy-l-lysine [A-Lys(Cbz)-OH], which contains a carboxylic acid and a protected amine-functionality in the monomer unit. Carboxylic acid-containing homopolymers, poly(A-Lys(Cbz)-OH), with predetermined molecular weights with relatively low polydispersities were initially synthesized by RAFT polymerization of A-Lys(Cbz)-OH. The chain extension of the dithiocarbamate-terminated poly(A-Lys(Cbz)-OH) to N-isopropylacrylamide (NIPAM) via the RAFT process and subsequent deprotection afforded the zwitterionic block copolymer composed of thermoresponsive poly(NIPAM) and poly(A-Lys-OH), which exhibited switchability among the zwitterionic, anionic, and cationic states by pH change. The assembled structures and thermoresponsive and chiroptical properties of these block copolymers were evaluated by dynamic light scattering, circular dichroism, and turbidity measurements. Finally, the cationic block copolymer, poly(A-Lys-OMe)- b-poly(NIPAM), was obtained by the methylation of the carboxylic acid group in the zwitterionic poly(A-Lys-OH) segment. Selective interactions of DNA with the cationic poly(A-Lys-OMe) segment in the lysine-based block copolymer were further evaluated by agarose gel electrophoresis and atomic force microscopy measurements, which revealed characteristic assembled structures and temperature-responsive properties of the polyplexes.

12 citations

Journal ArticleDOI
TL;DR: In this article, a chiral-achiral ampholytic block copolymers comprising poly(N-acryloyl amino acid) and poly(vinyl amine), poly(VAm), were synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization of N-ACryl-L-glutamic acid (A-Glu-OH), which has two carboxylic acid moieties.
Abstract: In this work, novel chiral-achiral ampholytic block copolymers comprising poly(N-acryloyl amino acid) and poly(vinyl amine), poly(VAm), were synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization of N-acryloyl-L-glutamic acid (A-Glu-OH), which has two carboxylic acid moieties. The precursor of the cationic poly(VAm) segment, poly(NVPI), was prepared by the RAFT polymerization of N-vinylphthalimide (NVPI), which was employed as the macro-chain transfer agent (CTA). RAFT polymerization of A-Glu-OH in the presence of the dithiocarbamate-terminated poly(NVPI) macro-CTA and subsequent deprotection afforded ampholytic block copolymers with positive poly(VAm) and negative poly(A-Glu-OH) segments. For comparison, an ampholytic block copolymer with an amino acid-based polyelectrolyte having one carboxylic acid moiety in the monomer unit was prepared by the RAFT polymerization of N-acryloyl-L-alanine (A-Ala-OH). The resulting ampholytic block copolymers formed self-assembled micelles with electrostatically complexed cores and anionic shells, which were affected by pH values and salt and urea concentrations. In these micelles, interpolyelectrolyte complexes between the cationic poly(VAm) and anionic amino acid-based segment, corresponding to the core and chiral segment [poly(A-Glu-OH) or poly(A-Ala-OH)], respectively, contribute towards the manipulation of the multi-stimuli-responsive properties and functions of the shell. Selective interactions of DNA with the cationic poly(VAm) segment in the block copolymer were further investigated.

11 citations

Journal ArticleDOI
02 Mar 2021-Langmuir
TL;DR: In this article, two block copolymers with zwitterionic and thermoresponsive segments were synthesized by the reversible addition-fragmentation chain transfer polymerization, and they were used to prepare mixed polyplex micelles with DNA.
Abstract: Two series of poly(vinyl amine) (PVAm)-based block copolymers with zwitterionic and thermoresponsive segments were synthesized by the reversible addition-fragmentation chain transfer polymerization. A mixture of the two copolymers, poly(N-acryloyl-l-lysine) (PALysOH) and poly(N-isopropylacrylamide) (PNIPAM), which have the same cationic PVAm chain but different shell-forming segments, were used to prepare mixed polyplex micelles with DNA. Both PVAm-b-PALysOH and PVAm-b-PNIPAM showed low cytotoxicity, with characteristic assembled structures and stimuli-responsive properties. The cationic PVAm segment in both block copolymers showed site-specific interactions with DNA, which were evaluated by dynamic light scattering, zeta potential, circular dichroism, agarose gel electrophoresis, atomic force microscopy, and transmission electron microscopy measurements. The PVAm-b-PNIPAM/DNA polyplexes showed the characteristic temperature-induced formation of assembled structures in which the polyplex size, surface charge, chiroptical property of DNA, and polymer-DNA binding were governed by the nitrogen/phosphate (N/P) ratio. The DNA binding strength and colloidal stability of the PVAm-b-PALysOH/DNA polyplexes could be tuned by introducing an appropriate amount of zwitterionic PALysOH functionality, while maintaining the polyplex size, surface charge, and chiroptical property, regardless of the N/P ratio. The mixed polyplex micelles showed temperature-induced stability originating from the hydrophobic (dehydrated) PNIPAM chains upon heating, and remarkable stability under salty conditions owing to the presence of the zwitterionic PALysOH chain on the polyplex surface.

10 citations

Journal ArticleDOI
TL;DR: The merit of using cross-linked BCPs in improving the long-term stability of OPVs is revealed, with the PBA70-Tri30 device showing superior thermal stability/photostability.
Abstract: In this study, a series of alcohol-soluble cross-linked block copolymers (BCPs) consisting of poly(n-butyl acrylate) (poly(nBA)) and poly(N-vinyl-1,2,4-triazole) (poly(NVTri)) blocks with different individual functions and lengths are designed and developed. These presynthesized cross-linked BCPs (PBAn–Trim) were, for the first time, revealed to exhibit many advantages in serving as the electron-extraction layer (EEL) for organic photovoltaics (OPVs). The cross-linked BCPs possessed intense ionic functionality, showing well capability to form effective interfacial dipoles at the indium tin oxide interface to facilitate the charge extraction at the corresponding interface. Furthermore, it also consisted a core–shell structure, wherein the polar poly(NVTri) core was well protected by the poly(nBA) shell to endow improved robustness against solvent erosion and thermal/photo inputs. Consequently, the PBA70–Tri30 device yielded a decent power conversion efficiency of 8.03% with a Voc of 0.83 V, much exceeding ...

9 citations


Cited by
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Journal ArticleDOI
TL;DR: Recent advancements to further the understanding of interactions between biomolecules and zwitterionic moieties are summarized and the molecular interactions between these molecules and biomolecule as determined by both experimental and theoretical studies are discussed.

97 citations

Journal ArticleDOI
TL;DR: It is desirable and urgent to summarize methods for obtaining active layer materials with long-term stability, mainly focusing on the chemical structure and blending morphology, as well as the corresponding degraded mechanism of OSCs.
Abstract: In the past 20 years, organic solar cells (OSCs) have made great progress in pursuing high power-conversion efficiencies, reaching the application threshold. Instead, device stability is becoming particularly important toward commercialization. There are many factors influencing the stability of OSCs, such as light, heat, humidity, oxygen, as well as device structure. Active layer materials, as the most critical functional layer in the devices, are greatly affected by these factors in terms of both efficiency and stability. Herein, it is desirable and urgent to summarize methods for obtaining active layer materials with long-term stability, mainly focusing on the chemical structure and blending morphology. Meanwhile, the corresponding degraded mechanism of OSCs is concluded and analyzed. In this outlook, challenges for developing high-performance and stable OSCs are discussed.

46 citations

Journal ArticleDOI
TL;DR: In this article, reversible addition-fragmentation chain transfer (RAFT) polymerization is discussed in terms of their potential and also advancements in the polymerization technology such as polymerization induced self-assembly or polymerization in continuous flow reactors are highlighted.
Abstract: Reversible addition–fragmentation chain transfer (RAFT) polymerization is an increasingly popular method of controlled radical polymerization and remarkable advances is made in recent years. This polymerization technique offers great chances for more sustainable routes to obtain tailor-made polymers with high precision. This article may be of interest not only for readers familiar with the technique, but also to newcomers to the field or colleagues, who are looking for more sustainable or safer polymerization techniques to obtain an extensive number of possible polymer structures. After an introduction to RAFT polymerization, different novel paths to carry out RAFT polymerization are discussed in terms of their potential and also advancements in the polymerization technology such as polymerization induced self-assembly or carrying out the polymerization in continuous flow reactors are highlighted. At the end some upcoming application areas of polymers prepared by RAFT are presented.

35 citations