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To functionalize a poly(isosorbide carbonate) (PIC)-based polymer and evaluate its recyclability, several types of diol comonomers were copolymerized with isosorbide. The thermal and mechanical properties and decomposition behavior of the PIC copolymers were investigated. The thermal stability of PIC was retained, and its glass transition temperature was systematically controlled by copolymerization. The decomposition of the PIC copolymers upon treatment with aqueous ammonia yielded monomers and urea, and the decomposition rate was governed by the structure of the comonomer.

Oligoisoprene macromonomer, which bears a terminal vinyl group and cis-1,4 regularity, was prepared by the metathesis degradation of high-molecular-weight polyisoprene with ethylene in a high selectivity and yield. The ethenolysis is also applicable for the degradation of natural rubber-derived polyisoprene, although the catalytic activity decreased. The prepared oligoisoprene macromonomer was successfully copolymerized with ethylene similarly with 1-hexadecene using a phenoxyimine-ligated titanium catalyst. The oligoisoprene-grafted polyethylene showed a typical stress‒strain curve, of which the tensile modulus and yielding stress are comparable to those of linear low-density polyethylene.

As porous polymer materials with continuous epoxy skeletons and pores, epoxy monoliths exhibit unique mechanical properties and fracture behavior different from the bulk thermoset of epoxy resins. In this article, we describe the thermal properties, pore structures, and mechanical properties of epoxy resins with tensile and compressive deformation of the monoliths. In addition, a change in the inner porous structure after large deformation was nondestructively observed by X-ray CT imaging.

Amine-cured epoxy resins bearing ester moieties were synthesized, and their properties, hydrolytic degradation behavior, and biomineralization were investigated. Neopentyl glycol diglycidate (NPG) was used as the epoxide and was cured with diethylenetriamine and isophoronediamine at different ratios. The T_gs and degradability were controlled using the composition of amines. To demonstrate their potential application as degradable materials for bone and dental repair, composites containing hydroxyapatite were prepared by curing NPG and the amines in the presence of HA. Bone-like apatite was grown on a composite by immersion in synthetic biofluid.

Our recent studies on the synthesis, characterization, degradation and applications of vinyl polyperoxides are reviewed. Primarily, the recent achievements in the design, biocompatibility, thermal and enzymatic degradation of water-soluble vinyl polyperoxides and copolyperoxides are described. Finally, future development possibilities and challenges of vinyl polyperoxides for various potential applications are summarised.

Acrylate polymerizations catalyzed by Lewis pairs (LP) composed of B(C₆F₅)₃ and various Lewis bases were investigated using two procedures based on different monomer/catalyst addition sequences. When Lewis bases were added to B(C₆F₅)₃-activated n-butyl acrylate (nBA) (procedure 1), the polymerization proceeded quantitatively using all Lewis bases. In contrast, the type of Lewis base significantly affected the polymerization results when nBA was added to interacting LPs (procedure 2). ¹⁹F nuclear magnetic resonance analysis of the LPs indicated that weakly interacting LPs efficiently initiated the polymerizations in procedure 2.

The depolymerization of super engineering plastics such as polysulfone (PSU) smoothly proceeded in the presence of methanol mediated by sodium hydroxide in 1,3-dimethyl-2-imidazolidinone (DMI) at 80 °C to form bis(4-methoxyphenyl)sulfone and 4,4’-(propane-2,2-diyl)diphenol (bisphenol A) in high yields. These products were readily isolated by simple filtration. The DMI solvent effectively promoted depolymerization and allowed insoluble resins such as polyetheretherketone (PEEK) to undergo the reaction. This method was applicable to other alcohols, such as ethanol and isopropyl alcohol.

The hydrogenolysis of PEG-modified soluble lignin was investigated with series of transition metal complexes to afford alkyl guaiacols. Although the introduced PEG moiety was also susceptible against the hydrogenolysis, in situ modification in PEG solvent was found effective for maintaining the lignin soluble and improved degradation efficiency.

A buffer solution of dual stimuli-responsive polymer with photodimerizable groups and temperature-responsive moieties undergoes a phase transition from a sol state to a gel state by exposure to ultraviolet light. The resulting gels changed the physical (elastic modulus) and chemical (hydrophilicity) properties by varying UV exposure time and temperature, respectively. Cell adhesion, spreading, and proliferation were strongly influenced by the physical and chemical properties of the polymer gels, which were regulated by varying UV exposure time and temperature.

The aggregation states from the interface to the bulk of the adhesive/adherend is a key to unraveling adhesion at the molecular level. We applied X-ray absorption spectroscopy (XAS) in combination with an Ar gas cluster ion beam (Ar GCIB) to poly(methyl methacrylate) (PMMA) films adsorbed onto a SiO_x/Si(111) surface. GCIB-XAS analysis revealed that the orientation of the C=O group in the side chain of PMMA differs between the region from the SiO_x interface to a distance on the order of 1 nanometer and the bulk PMMA region.

In this review, we show that reversibility of charge storage occurs in polymers with bistable redox-active groups populated in the repeat units of a nonconjugated backbone, especially when an electron self-exchange reaction spreads throughout the polymer. We will also show that extending the idea of electron exchange to electron/proton exchange leads to reversible hydrogen storage based on the bistability of hydrogenated and dehydrogenated states and the equilibrium for hydrogenation.

We added lithium (trifluoromethane sulfonyl) imide (LiTFSI) salt into an immiscible poly(methyl methacrylate) (PMMA)/ethylene-vinyl alcohol copolymer (EVOH) to improve the transparency and tensile properties. The addition of LiTFSI reduced the refractive index of EVOH, which matched the refractive index of PMMA, resulting in high transparency. In addition, LiTFSI interrupted the intra- and intermolecular hydrogen bonds between the OH groups in EVOH, resulting in decreased crystallinity. Consequently, the amorphous and flexible EVOH domains in the PMMA matrix changed the tensile properties from brittle to ductile by suppressing the stress concentration.

The tensile strength of short carbon fiber (SCF)-reinforced plastics (SCFRPs) prepared by injection molding with various functionalized polypropylenes (PPs) using different types and contents of functional groups and crystallinity, depended on interfacial adhesion. Functionalized PP with more functional groups added to the side chains (PP-g- MA1) exhibited higher interfacial adhesion near the SCFRP surface where the SCF filaments and PP chains were highly oriented in parallel than that with fewer functional groups (PP-t-MA).

Although a fundamental problem, the effect of node functionality on network fracture has yet to be clarified. This study performed phantom chain simulations for networks made from star polymer mixtures with different functionalities. The results reveal that the fracture characteristics lie on the master curves if they are plotted as functions of the cycle rank of the network, irrespective of the mixing ratio and the conversion rate.

Electrically conductive porous materials consisting of cellulose nanofiber (CNF) and graphene were prepared with postreduction processes. Porous CNF/graphene oxide (GO) composites were used as precursors and the reduction of the GO under dry conditions was carried out. Both thermal and chemical reduction processes successfully proceeded to obtain the porous CNF/reduced GO (rGO) composites, in which the conductive path was effectively fabricated owing to the good dispersibility of GO sheets. As a result, the porous CNF/rGO exhibited high electrical conductivity of up to 1.39 × 10^–3 S/m.

The characteristic ratios C_∞ of syndiotactic, isotactic, and atactic hydrogenated ring-opened poly(norbornene)s, H-poly(NB)s, were determined in 1,2,4-trichlorobenzene at 140 °C with molecular dynamics simulations and size exclusion chromatography with a multiangle light-scattering online detector (SEC-MALS). The C_∞ results were 11, 14 and 12 for syndiotactic, isotactic and atactic H-poly(NB), respectively, all of which were consistent with the rotational isomeric state model, and definitely larger than those for polyethylene and polypropylenes. The stiffness of the H-poly(NB) chains was induced by the cyclopentane ring in the chains.

To examine the behavior of degradation by a conjugate substitution reaction in aqueous media, the degradation of a poly(conjugated ester), prepared from 1,4-butylene bis[α-(bromomethyl)acrylate] and fluorescein, with aqueous solution of various nucleophiles was investigated using UV‒vis spectrometry and size-exclusion chromatography. At the earliest stage of the degradation, the affinity between the nucleophile and the polymer affected the reaction rate, leading to faster degradation for relatively hydrophobic amines. On the other hand, hydrophilic nucleophiles that produce water-soluble degradation products promoted complete chain scission.

A degradable cross-linked polybutadiene was synthesized using a peptide-based cross-linker. As a degradable cross-linker, we synthesized poly(L-cysteine) (polyCys) by papain-catalyzed chemoenzymatic polymerization. The thiol-ene reaction between polybutadiene and polyCys was conducted in the presence of a radical initiator, resulting in the formation of an insoluble polybutadiene gel. The successful cross-linking and network formation was confirmed by Raman spectroscopy and viscoelastic analysis. Dynamic viscoelastic measurements of the cross-linked polybutadiene revealed the disappearance of slow relaxation mode. The polyCys-linked polybutadiene underwent degradation through acidic hydrolysis, allowing the recovery of soluble polybutadiene.

This study explores enhanced electrical properties in conductive polymers, particularly PEDOT:PSS, by creating multilayered films. Initial findings show a sheet resistance of 1639 Ω□^-1 for a single layer, but applying three additional layers reduces it to 29 Ω□^-1, boosting conductivity from 2.6 to 18.3 Scm^-1. Similar improvements are observed with formulations containing Tween 80. Analysis via X-ray diffraction and Raman spectroscopy indicates increased crystalline order and a benzoid to quinoid shift. Surface profiling reveals growing roughness with additional PEDOT:PSS layers, partially mitigated by Tween 80.

Tributylborane-initiated graft polymerization of methyl methacrylate on a poly(vinylidene fluoride) film was successfully achieved. The reaction was affected by the temperature and concentration of tributylborane, and a 41% graft yield was obtained under the optimized conditions. This value was higher than those obtained with other methods. This method facilitated modifications of only the surface of the poly(vinylidene fluoride) film, which was confirmed by IR spectroscopy and cross-section observations. New physical properties were added to the surface, such as hydrophilicity.