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Hydroxy-functional poly(propenyl ether)s are promising thermoresponsive materials; here we establish a controlled synthesis via living cationic polymerization of silyl-protected monomers. Among the silyl protecting groups examined, only tert-butyldiphenylsilyl (TBDPS) enabled living cationic polymerization. The living cationic polymerization of tert-butyldiphenylsiloxybutyl propenyl ether (TBDPSBPE) afforded a high-molecular-weight polymer (poly(TBDPSBPE)) with a narrow molecular weight distribution (Mn = 12,900; Mw/Mn = 1.22). Additionally, chain propagation continued in monomer addition experiments, and the molecular weight increased further with a narrow molecular weight distribution, confirming the success of living cationic polymerization. Poly(TBDPSBPE) was successfully desilylated to afford poly(HBPE) with a narrow molecular weight distribution. Poly(HBPE) exhibited a glass transition temperature (Tg) of 44 °C, 82 °C higher than that of the corresponding polymer without β-methyl groups, poly(HBVE). The enhanced thermal properties of poly(HBPE) were attributed to the steric hindrance of the β-methyl group, which fixes the position of the hydroxy group and allows stronger hydrogen bonding. To investigate the aqueous thermoresponse, a hydroxylated analog with a shorter side-chain spacer (poly(HPPE)) was synthesized, and poly(HPPE) exhibited lower critical solution temperature (LCST)-type phase separation in water with a cloud-point temperature (Tcp) of 6 °C, showing reversible transitions with thermal hysteresis.

Hydroxy-functional poly(propenyl ether)s are promising thermoresponsive materials; here we establish a controlled synthesis via living cationic polymerization of silyl-protected monomers. Among the silyl protecting groups examined, only tert-butyldiphenylsilyl (TBDPS) enabled living cationic polymerization. The living cationic polymerization of tert-butyldiphenylsiloxybutyl propenyl ether (TBDPSBPE) afforded a high-molecular-weight polymer (poly(TBDPSBPE)) with a narrow molecular weight distribution (M [sub.n] = 12,900; M [sub.w]/M [sub.n] = 1.22). Additionally, chain propagation continued in monomer addition experiments, and the molecular weight increased further with a narrow molecular weight distribution, confirming the success of living cationic polymerization. Poly(TBDPSBPE) was successfully desilylated to afford poly(HBPE) with a narrow molecular weight distribution. Poly(HBPE) exhibited a glass transition temperature (T [sub.g]) of 44 °C, 82 °C higher than that of the corresponding polymer without β-methyl groups, poly(HBVE). The enhanced thermal properties of poly(HBPE) were attributed to the steric hindrance of the β-methyl group, which fixes the position of the hydroxy group and allows stronger hydrogen bonding. To investigate the aqueous thermoresponse, a hydroxylated analog with a shorter side-chain spacer (poly(HPPE)) was synthesized, and poly(HPPE) exhibited lower critical solution temperature (LCST)-type phase separation in water with a cloud-point temperature (T[sub.cp]) of 6 °C, showing reversible transitions with thermal hysteresis.

Cationic polymerization of 2-adamantyl vinyl ether (2-vinyloxytricyclo[3.3.1.1 3,7 ]decane; 2-AdVE) and copolymerization of 2-AdVE with n -butyl vinyl ether (NBVE), 2-methoxyethyl vinyl ether (MOVE), or 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA), vinyl ethers containing a flexible chain or a polymerizable group, were performed to obtain poly(vinyl ether) plastics for optical use. With the living cationic initiating systems such as isobutyl vinyl ether–acetic acid adduct/ethylaluminum sesquichloride (IBEA/Et 1.5 AlCl 1.5 ) or the hydrogen chloride/zinc chloride (HCl/ZnCl 2 ), all the obtained copolymers had unimodal and relatively narrow molecular weight distributions (polydispersity ratio: M w / M n  = ~1.5 at high conversion) throughout the copolymerizations. These results indicate that the copolymerizations of 2-AdVE with the three comonomers led to the statistical copolymers without contamination of homopolymers. With BF 3 OEt 2 as an initiator, homopolymer of 2-AdVE and poly(2-AdVE)-based polymers, poly(2-AdVE- stat -NBVE), poly(2-AdVE- stat -MOVE), and poly(2-AdVE- stat -VEEA), were produced with high-molecular weights ( M n  = 31,800–116,000) in toluene at −30 °C in quantitative yield within 10 min. They have excellent thermal stability owing to their high glass transition and thermal decomposition temperatures. The transparency (86–91 %) and refractive index (1.52–1.53) of the molded polymers are similar to those of conventional optical plastics such as poly(methyl methacrylate) (PMMA) and polycarbonate (PC), whereas their specific gravity (1.09–1.12) and water absorption (0.06–0.17 %) are significantly lower than those of PMMA and PC. In addition, the Abbe number of poly(2-AdVE), poly(2-AdVE- stat -NBVE), and poly(2-AdVE- stat -MOVE) exceeded 60 and was higher than those of PMMA and PC, indicating that the poly(2-AdVE)-based plastics are very suitable for optical lens.

Hydroxy-functional poly(propenyl ether)s are promising thermoresponsive materials; here we establish a controlled synthesis via living cationic polymerization of silyl-protected monomers. Among the silyl protecting groups examined, only -butyldiphenylsilyl (TBDPS) enabled living cationic polymerization. The living cationic polymerization of -butyldiphenylsiloxybutyl propenyl ether (TBDPSBPE) afforded a high-molecular-weight polymer (poly(TBDPSBPE)) with a narrow molecular weight distribution ( = 12,900; / = 1.22). Additionally, chain propagation continued in monomer addition experiments, and the molecular weight increased further with a narrow molecular weight distribution, confirming the success of living cationic polymerization. Poly(TBDPSBPE) was successfully desilylated to afford poly(HBPE) with a narrow molecular weight distribution. Poly(HBPE) exhibited a glass transition temperature ( ) of 44 °C, 82 °C higher than that of the corresponding polymer without β-methyl groups, poly(HBVE). The enhanced thermal properties of poly(HBPE) were attributed to the steric hindrance of the β-methyl group, which fixes the position of the hydroxy group and allows stronger hydrogen bonding. To investigate the aqueous thermoresponse, a hydroxylated analog with a shorter side-chain spacer (poly(HPPE)) was synthesized, and poly(HPPE) exhibited lower critical solution temperature (LCST)-type phase separation in water with a cloud-point temperature (T ) of 6 °C, showing reversible transitions with thermal hysteresis.

A soluble and stable one-handed helical poly(substituted phenylacetylene) without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer followed by two-step polymer reactions in membrane state: (1) removing the chiral groups (desubstitution); and (2) introduction of achiral long alkyl groups at the same position as the desubstitution to enhance the solubility of the resulting one-handed helical polymer (resubstitution). The starting chiral monomer should have four characteristic substituents: (i) a chiral group bonded to an easily hydrolyzed spacer group; (ii) two hydroxyl groups; (iii) a long rigid hydrophobic spacer between the chiral group and the polymerizing group; (iv) a long achiral group near the chiral group. As spacer group a carbonate ester was selected. The two hydroxyl groups formed intramolecular hydrogen bonds stabilizing a one-handed helical structure in solution before and after the two-step polymer reactions in membrane state. The rigid long hydrophobic spacer, a phenylethynylphenyl group, enhanced the solubility of the starting polymer, and realized effective chiral induction from the chiral side groups to the main chain in the asymmetric-induced polymerization. The long alkyl group near the chiral group avoided shrinkage of the membrane and kept the reactivity of resubstitution in membrane state after removing the chiral groups. The g value (g = ([θ]/3,300)/ε) for the CD signal assigned to the main chain in the obtained final polymer was almost the same as that of the starting polymer in spite of the absence of any other chiral moieties. Moreover, since the one-handed helical structure was maintained by the intramolecular hydrogen bonds in a solution, direct observation of the one-handed helicity of the final homopolymer has been realized in CD for the solution for the first time.

A vinyl ether containing a five-membered cyclic carbonate group, 2-(2-vinyloxyethoxy)ethyl carbonate ( VEECN ), was synthesized by adding CO 2 to 2-(2-vinyloxyethoxy)ethyl glycidyl ether, which is a vinyl ether containing an epoxy group. Cationic polymerization of VEECN was performed in nitromethane at − 30 °C with boron trifluoride etherate. The resulting poly( VEECN ) exhibited a number-average molecular weight of ~ 3500 g/mol and a molecular weight distribution of ~ 1.40. Poly[2-(2-vinyloxyethoxy)ethyl hydroxyurethane]s [poly( VEEHU )- C 2 to -C 5 ] were synthesized by reacting the cyclic carbonates in the side chains of the obtained poly( VEECN) with four alkanolamines with different methylene numbers (2–5) to form hydroxyurethane groups. The reaction ratios were adjusted to approximately 50%, 75%, and 100%, and the thermal responses and properties of poly( VEEHU ) -C 2 to -C 5 were investigated. When the urethanization ratio was ~ 50%, the cloud points ( T cp ) of 1% w/v poly( VEEHU ) -C 3 to -C 5 aqueous solutions were observed at 46, 27, and 8 °C, respectively, with the temperature decreasing with increasing methylene number. Conversely, the poly( VEEHU ) -C 2 aqueous solution did not exhibit a T cp at ≤ 95 °C. The glass transition temperatures of the polymers were − 32 °C for poly( VEECN ) and − 28, − 32, − 33, and − 35 °C for poly( VEEHU ) -C 2 to -C 5 , respectively. Additionally, the thermal decomposition temperatures of the polymers were 279 °C for poly( VEECN ) and 253–262 °C for poly( VEEHU ) -C 2 to -C 5 , indicating that poly( VEEHU ) were flexible polymers at room temperature with relatively high thermal stabilities.

Fully aromatic polyimide particles were obtained in a single step via the polycondensation of diethyl (hexafluoroisopropylidene)diphthalate (6FE) and 4,4′-oxydianiline (ODA) using polyvinylpyrrolidone (PVP) as a steric stabilizer in ethylene glycol. Since the monomers are soluble in ethylene glycol, but the polyimide is insoluble, the polyimide particles grew gradually during the polycondensation process. The particle size and size distribution were controlled by varying the molecular weight and amounts of PVP. The particle size decreased with both increasing concentration and increasing molecular weight of the stabilizer. Furthermore, the solvent composition affected the particle size, i.e., the particle size decreased with increasing volume of glycerol as a cosolvent. Monodisperse particles (diameter: 8.5–1.8 μm) were obtained by varying the amounts of PVP and glycerol.

A ruthenium complex prepared in situ from [RuCl2(p-cymene)]2 and TpMe2K [TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate] is efficient for aromatic C–H borylation with pinacolborane (4,4,5,5-tetramethyl-1,3,2-dioxaborolane). Arenes were borylated at more electron-rich positions. DFT calculations and kinetic isotope effect experiments suggest that the catalytic cycle should involve an electrophilic aromatic substitution with a borenium cation.

Homochiral or enantioenriched helical polymers are essential for investigating the relationship between chirality of helical structures and their performance in the design of various optically active functional polymers. We have succeeded in obtaining the helical poly(phenylacetylene)s poly( 1 )–poly( 6 ) possessing no chiral moieties, except for helicity; the enantioenriched helical sense of these polymers was induced by transformation in chiral solvents, followed by removal of the chiral solvents, even if the interaction between the chiral molecule and the polymer was weak such as solvent–solute interaction. In particular, the newly synthesized poly( 6 ) retained the induced helical sense even in an achiral solvent. A series of racemic helical or achiral poly(phenylacetylene)s were prepared, and the preferential helical sense of the polymers was induced by transformation in chiral solvents, even if the interaction between the chiral molecule and the polymer was weak such as solvent–solute interaction. The enantioenriched helical poly(phenylacetylene)s possessing no chiral moieties except for helicity were obtained by removal of chiral solvents. In particular, one of them retained the induced helical sense even in an achiral solvent.

Nucleotide sequences in internal transcribed spacer (ITS)-1 region derived from dried nori products produced in Japan, China, and the Republic of Korea were compared. Thalli contained in the Japanese products were genetically homogenous, and their nucleotide sequences in ITS-1 were identical to those of the reference strains of Pyropia yezoensis f . narawaensis . In Chinese products, the thalli were related to P. yezoensis strain Minomiasakusa. In contrast, the thalli in the Korean products were genetically heterogeneous, and several different P. yezoensis strains and other Pyropia spp. were used for dried nori products. In some thalli produced in both China and Korea, the DNA sequences of the ITS-1 region were identical with that of Japan, suggesting that the cultivar strains might have been transplanted from Japan to China in recent years. The 432-bp-long nucleotide sequences in the ITS-1 region of thalli derived from Japanese origin were cleaved to two restriction fragments at 154 and 278 bp by cleavage of PCR-amplified products using Msp I. Conversely, almost all of the corresponding sequences derived from China and Korea were lacking Msp I or other restriction patterns, except for nori products from some areas that cultivate a closely related strain to the Japanese cultivar.