Original Article in 2022

Poly(substituted methylene)s possess higher dense side chains and their chain mobilities are restricted, relative to conventional vinyl polymers. The surface of poly(substituted methylene)s was more hydrophobic. In particular, the poly(substituted methylene) with perfluoroalkyl groups showed lower surface free energy than the corresponding vinyl polymer. Moreover, the surface of block-like copolymer of poly(substituted methylene) was more hydrophobic than that of random copolymer. The preparation methods of films of poly(substituted methylene) with ethyl ester side chains controlled their surface free energies and structures.

We demonstrate the preparation of composite vitrimer-like materials containing silica nanoparticles (SNPs), where the matrix is composed of polyacrylate-based polymers crosslinked via a pyridine–bromo quaternization reaction. The quaternized pyridine at the crosslinking point exchanges the bond pair via trans-N-alkylation at high temperatures. Thermal and mechanical investigations first reveal the formation of the bound rubber phase around the SNP, which eventually affects the relaxation behaviors at high temperatures. In the final section, some useful functions owing to the bond exchange nature, such as reprocessability and recyclability, are exhibited.

A side-chain crystalline block copolymer (SCCBC) was applied for the chemical modification of polyethylene surfaces. A block copolymer with stearyl and epoxy groups was prepared by nitroxide-mediated living radical polymerization. This copolymer had a phase transition temperature of ~40 °C. When the SCCBC was immobilized on polyethylene, a polymeric layer with nucleophilic reactivity was formed. The layer thickness increased with increasing copolymer concentration. Galactoside ligands were added to the polymeric layer by the ring-opening addition reaction of the epoxide. The glyco-functionalized interface exhibited specific protein binding.

The first main-chain type triphenylarsine (AsPh₃) polymers were synthesized by Suzuki-Miyaura polycondensation. The electronic and photophysical properties of the AsPh₃ polymers were comparison with model compounds by experimental and computational methods. As a result, it was found that the conjugated systems were expanded through the arsenic atoms. The present AsPh₃ polymers are promising as luminescent materials.

The direct characterization of various loops with different topologies within polymer networks remains a major challenge in the field of polymer and materials science. We propose a partially junction-cleavable network as a universal platform for directly probing various loops in polymer networks. Various loops are formed in the copolymerization of deliberately designed polyfunctional monomers with partially cleavable and uncleavable junctions. The network transforms to soluble oligomers through cleavage at the junctions, and partial loops are preserved. The preserved monoloops and spiro-biloops with various sizes are directly qualified by MALDI-TOF MS, which has never been achieved by any current methods.

In this work, POSS with an acetylacetonato group (POSS-acac) and metal–coordination polymers comprising POSS-acac (CP(Metal)s) were synthesized. The possible structure of CP(Metal)s was estimated from the UV–Vis spectrum and the residual mass after burning off and the surface morphologies of the CP(Metal)s were observed using scanning electron microscopy.

No new chemical compounds were found in the copolymer acrylamide – acrylonitrile – sodium 2-acrylamido-2-methylpropanesulfonate with the composition of [72]:[10]:[18] that was subjected to thermohydrolysis at temperatures up to 160 °C, with the exception of carboxyl groups in place of amides. Thermohydrolysis up to 200 °C causes partial degradation and changes in the acrylate copolymer. The intrinsic viscosity, molecular weight and average sizes of the solvated copolymer macromolecular coils were found to decrease with increasing hydrothermal treatment temperature.

The biobased, rigid, and fire-retardant monomer (BDBE) was synthesized and employed in furanic polyester (PECBFs) preparation. The T_g of PECBFs increased up to 95 °C when BDBE content reached 25%. In combustion test, the samples self-extinguished immediately when BDBE content are more than 15%. The obtained copolyesters were expected to be applicated in the fields of firefighting materials and electronics.

Silver(I) ions in nonpolar solvents were used to polymerize expanded l-lysine and l-ornithine derivatives. Introducing a bulky hydrophobic acyl group into the terminal amino group of the side chain increased the solubility of the amino acid in chloroform. Polymerization proceeded via the formation of head-to-head and tail-to-tail linkages, which resulted in chiral helical structures. Circular dichroism measurements and density functional theory calculations were used to estimate the overall secondary structures, which were significantly different from each other despite the small difference, namely, with or without the fourth CH₂ moiety.

The shear-induced crystallization behavior of the blends of cyclic polyethylene (C-PE) and linear polyethylene (L-PE) was investigated. This figure shows the formation rate of shish-like fibril crystals (I) in the blend systems of C-PE(230k)/L-PE(42k) and C-PE(230k)/L-PE(104k) against the weight fraction of L-PE, Φ_L-PE. I reached a maximum at a certain Φ_L-PE. As Φ_L-PE increased, that is, as the entanglement density increased, the formation of the oriented melt was promoted. Crystallization was also suppressed by the entanglements. The maximum value of I was observed owing to these two competing factors.

Synergistic effects of adding silica, as a secondary filler, to styrene-butadiene rubber composites highly filled with carbon black was investigated. It was shown that there is a critical concentration of silica at which improvements in the Payne effect, mechanical properties, abrasion resistance, and heat build-up were at extrema. This behavior was attributed to the filler networking in the hybrid filler systems, at which work of adhesion in a three-component system was considered as the driving force for flocculation of the primary filler and final morphology of fillers in hybrid composites.

Systematic trade-off relationship between increased stress and decreased strain range at soft elasticity with the addition of crosslinkers in liquid crystal elastomers (LCEs). Control of the crosslink density is within the range of already-established synthetic process adjustments. By selecting the molar ratio of the crosslinkers, the set of stress and strain range at soft elasticity can be fixed arbitrarily. By controlling the crosslink density of LCEs at different sites, multimodal actuators can be realized.

PLA-pectin biocomposites were prepared at pectin contents from 2 to 8% w/w. The mechanical properties of PLA-pectin were considerably improved after the annealing process, especially at 4% w/w of pectin according to being the best dispersion indicated by SEM and synchrotron-based FT-IR mapping. Moreover, pectin aids in the crystallization of PLA confirmed by in situ SR-WAXS. The crystallization rate and crystallinity were maximum at 8% w/w pectin addition. Finally, the pectin dispersion is the main factor in determining the mechanical and thermal properties of biocomposites.

Amphiphilic peptides bearing an alternating binary pattern of hydrophilic and hydrophobic repeating units were synthesized via polymerization exploiting Ugi’s four-component condensation reaction (Ugi’s 4CC) as the elemental polymerization reaction. We performed turbidity measurements on the aqueous polymer solutions at various temperatures. The results showed that the structural effects of the alternating peptides had the following impacts on thermoresponsiveness: (i) alternating peptides consisting of repeating hydrophilic and hydrophobic units tended to adopt upper critical solution temperature (UCST) behavior; and (ii) when the hydrophobes in the polymer were large enough for the intrachain hydrophobic interactions, the polymer displayed lower critical solution temperature (LCST) behavior. We also prepared thermoresponsive hydrogels comprising alternating peptide skeletons as the cross-linking points. Alternating peptides with LCST behavior may be useful for creating peptide-based smart materials in the future.

Spherical hydrogels (ENTG-co-PSβCyD) were prepared by photocopolymerization of the polyethylene glycol macromonomer ENTG and the polysubstituted photocross-linkable β-cyclodextrin (β-CyD) macromonomer PSβCyD. The optimum composition ratio for use of this hydrogel as a microbe-immobilized support was examined, along with the phenol (PhOH)-removing capability of PhOH-decomposing bacteria immobilized on this hydrogel. The best microbe-immobilized support had a PhOH-removal rate of 0.76 mg (L h hydrogel g)⁻¹. This removal rate was 1.7 times faster, and the amount of free bacteria in the assay medium was 3.6 times lower than the corresponding data obtained using a microbe-immobilized hydrogel without PSβCyD.

Amine-containing polysilsesquioxane (PSQ) membranes were studied with regard to their CO₂ separation ability. PSQ membranes were prepared by using amine-containing monomers, bis(triethoxysilylpropyl)amine (BTESPA), (aminopropyl)triethoxysilane (APTES), and (aminoethylaminopropyl)triethoxysilane (AEAPTES). The CO₂ permeances of the membranes prepared by 1:1 copolymerization with bis(triethoxysilyl)ethane increased in the order of AEAPTES-derived membranes < APTES-derived membranes < BTESPA-derived membranes, and their CO₂/N₂ permselectivities decreased in the same order. Copolymerization under acidic conditions resulted in the formation of ammonium-containing membranes with improved CO₂ permeances and acceptable CO₂/N₂ permselectivities.

Living radical polymerization was carried inside a liposome to prepare a deformable nanocapsule. The obtained nanocapsules showed good absorption of chemical substances depending on the binding ability to the incorporated polymers, and the absorption capacity could be controlled by the length and dissolved state of the polymer chains. Dynamic morphological changes in the capsules were observed when liposomes with high membrane fluidity were employed. Deformation of nanocapsules were induced by altering the pH value and ionic strength, resulting in the release of cargo in response to these environmental conditions.

A newly synthesized polyurethane (PU) was used to increase the flexibility of Bombyx mori silk fibroin (SF) fiber by making a composite of SF and PU, which is expected to increase applications of SF fiber in biomaterials. Namely, the elongation at break of the fiber increased by 1.3–1.8 times compared with that of regenerated SF fiber. The main reason for the increased flexibility of the SF-PU composite fiber is the increase in the fraction of random coils in SF, which was clearly observed by ¹³C solid-state NMR.

Perfect syndiospecific polymerization of triphenylamine-substituted styrene derivatives were achieved by using a rare-earth metal catalyst. The copolymerization of FSt with Styrene afforded copolymers have random or gradient sequence distributions and easily tunable incorporation rate.

Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrene sulfonate) (PEDOT: PSS) films have strong potential for application in flexible transparent conductive electrodes. In this study, the electrical conductivity of PEDOT: PSS is shown to be enhanced by a bisphenol additive, bis (4-hydroxyphenyl) sulfone (BPS). The effects of BPS on the chemical structure of PEDOT: PSS were investigated using X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy. The PEDOT: PSS conformation is found to undergo a transformation into a highly conductive structure following the addition of BPS.