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This review is focused on evolutions of precision radical polymerizations in various directions from metal-catalyzed Kharasch addition or atom transfer radical addition (ATRA). The developments include metal-catalyzed living radical polymerizations via reversible activation of carbon-halogen bonds, metal-catalyzed step-growth radical polymerizations of designed monomers having an unconjugated vinyl group and a reactive carbon-halogen bond, simultaneous metal-catalyzed chain- and step-growth radical polymerization for producing degradable vinyl copolymers with main-chain ester units, and vinyl monomer sequence control via combinations of iterative ATRAs and various controlled polymerizations.
This review focuses on the controlled radical polymerization of vinyl ether (VE) and the related self-assemblies. VE was long believed to be among the monomers that could not be radically homopolymerized. Under such circumstances, some groundbreaking polymerizations of VE have been discovered. Advances in research have made it possible to perform controlled radical polymerization with VE due to hydrogen bonds and/or cation-π interactions between VE monomers and the propagating radical. By using the resulting poly(VE)s, various functional polymers and nano-objects via polymerization-induced self-assembly can be obtained.
Among stimuli-responsive polymers, thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) is the most widely investigated. PNIPAAm-based polymers can undergo appropriate changes in response to their external environment. In this focus review, recent advancements in the applications of stimuli-responsive polymers based on PNIPAAm in biomedical fields are summarized, with an emphasis on our own research. In particular, a summary of the design of polymers for application in the separation and purification of (bio)pharmaceutical products and controlled cellular uptake is provided.
This focus review discussed our recent developments of unnatural glycopolymers based on polyoxazoline, protein–polymer conjugates, and protein stabilization. To develop new glycopolymers, a bicyclic monomer composed of glucosamine and 2-methyl-2-oxazoline (MeOx) was designed. This cationic ring-opening polymerization proceeded not by the mechanism for MeOx but by a new polymerization mechanism. This oligosaccharide has promise to be applied to a new glycomaterial owing to the polymer design. Additionally, protein conjugation and encapsulation by amphiphilic/fluorous chain-folding nanoparticles were investigated. Fluorous nature in random copolymers was useful for the protein conjugation and stabilization.
In situ infrared spectroscopy and two-dimensional (2D) correlation analysis was applied to research the chemical changes and curing reaction mechanism of epoxy resin and amine curing agents. The curing reaction mechanism can be deeply understood from the results. Due to the nucleophilic addition reaction of amino and epoxy groups, the nitrogen atoms easily combine with the carbon atoms, which forms new C-N groups. Then, the C-O bonds break; finally, as the N-H bonds in primary amines break, the hydrogen atoms combine with the oxygen atoms to form new hydroxyl groups.
Asymmetric combinations of chiral 2-hydroxyalkanoic acid (2HAA)-based random copolymers with monomer compositions of approximately 50/50, which can form stereocomplex (SC) crystallites, are reported. The copolymer combinations were l-configured individually crystallizable poly(l-lactic acid-co-l-2-hydroxybutanoic acid) or poly(l-2-hydroxybutanoic acid-co-l-2-hydroxy-3-methylbutanoic acid) and d-configured individually noncrystallizable poly(d-lactic acid-co-d-2-hydroxy-3-methylbutanoic acid). This study strongly suggests that SC crystallization occurred when the common monomer units were incorporated into both l- and d-configured 2HAA-based random copolymers. SC crystallization of new types of asymmetric combinations is expected to diversify the attainable properties and biodegradation behavior of chiral 2HAA-based polymer materials.
P3HT embedded with N- and NS-GQDs exhibit quite similar crystallinities independently of the solvent used, as suggested by our molecular dynamics calculations for the amorphous and crystalline regions. The vibrational, optical and impedance spectroscopy features suggest charge carrier formation in both the amorphous and crystalline regions but only for the P3HT:NS-GQDs system in relation to the donor:acceptor interactions evidenced by our DFT calculations.
The drug release behaviors of gelatin hydrogels prepared with polymers in terms of their rheological properties were evaluated. In the oscillatory strain sweep, gelatin/HPMCP hydrogels showed a higher crossover strain (Tan δ = 1) than gelatin and gelatin/Eudragit® hydrogels. Thus, gelatin/HPMCP hydrogels had the property of elastic hydrocolloids and tended to keep the platform compared with other sample hydrogels. As a result, the drug release from gelatin/HPMCP hydrogels was delayed compared with other sample hydrogels at pH 1.2.
Bioderived polyimide with outstanding thermal-mechanical stability, water absorption and dielectric properties is an excellent substrate or dielectric material for next-generation electronics.
We demonstrated biomolecular motors driven swarming of microtubules and their dissociation under UV and visible light irradiation, respectively. A photoresponsive molecule, para tert-butyl-substituted azobenzene was incorporated to the backbone of single strand DNA, which functions as a photoswitch to control the swarming of microtubules in a reversible manner. This work is expected to expand the potential applications of biomolecular motors in developing photoregulated molecular machines.
