Stereospecific reversible deactivation radical polymerization of biomass‐based acrylates for precise control of tacticity and molecular weight

Reversible deactivation radical polymerization (RDRP) of biomass‐based acrylates, (S )‐ and (R )‐2‐isopropyl‐5‐methylene‐1,3‐dioxolan‐4‐ones (S‐MiPDO and R‐MiPDO), was successfully performed to produce a well‐defined polymer with simultaneously controlled tacticity and molecular weight, and low dispersity (? < 1.3). In particular, meso triad (mm ) of the polymer was continuously controlled as designed from 28.1% to about 100% by changing the molar ratio of S‐MiPDO/R‐MiPDO in feed. In kinetic studies, the rate of RDRP was strongly influenced by the stereostructures of the propagating radical, and it was much lower in isospecific RDRP than atactic one in reversible chain transfer catalyzed polymerization (RTCP) in contrast to atom transfer radical polymerization (ATRP) where the rate would not change regardless of the tacticity. Increase of molecular weight and low ? of the polymer were also observed in reversible addition‐fragmentation chain transfer (RAFT) polymerization of MiPDO. In addition, block copolymers including stereoblock copolymers were feasibly synthesized by RTCP of styrene and methyl methacrylate using poly(MiPDO) prepolymer. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 445–456     

Characterization of Cu species on SiO2 and ZSM-5 by temperature-programmed reduction by ammonia

We studied the temperature-programmed reduction by NH₃ (NH₃-TPR) as a supplement to the temperature-programmed reduction by H₂ (H₂-TPR) for the characterization of supported Cu species. The NH₃-TPR profile of Cu/SiO₂, which contained only bulk CuO, exhibited two peaks for N₂ formation in equal amounts, suggesting stepwise reduction of the bulk CuO. In contrast, the H₂-TPR profile exhibited only one H₂ consumption peak. We also studied Cu-NaZSM-5 samples with various Cu and Na loadings. The Cu ions on ZSM-5 were reduced to Cu⁺ but no further. Kinetic analysis revealed that the NH₃-TPR profile exhibited peaks for separate reductions of isolated and binuclear Cu²⁺ ions. Thus, we found NH₃-TPR to be useful for detailed analysis of the reducibility of Cu²⁺ to Cu⁺ in zeolite pores.     

Preparation and Free-Radical Polymerization of 2,4-Dichloro-6-(p-Vinylphenyl)-1,3,5-triazine as a Reactive Monomer Containing Two Replaceable Groups

Abstract

A new monomer containing two replaceable groups, 2,4-dichloro-6-(p-vinylphenyl)-1,3,5-triazine (DCVT) was prepared by the reaction of p-vinylphenylmagnesium chloride with cyanuric chloride. This monomer was polymerized readily in benzene by AIBN at 60°C. From the copolymerization with styrene, Q and e values of DCVT were obtained as Q = 2.42 and e = 0.08. An insoluble terpolymer prepared from DCVT, styrene, and divinylbenzene was treated with several nucleophilic reagents, including sodium methoxide, sodium methylmercaptide, dimethylamine, and triethylphosphite, to afford the corresponding polymers in high conversions.     

Formation of the Liquid Crystal of a Surface-active Dye in Aqueous Methanol Solutions

The formation of the liquid crystal phase of a surface-active dye, p-octylphenol yellow amine poly(ethylene oxide), in aqueous methanol solutions has been examined by optical microscopy. Rodlike swarms appear at relatively low dye concentrations only slightly higher than the second critical micelle concentration. They develop into liquid crystal phase when the dye concentration is further increased. It takes some hours for the formation of a stripe-like texture characteristic of nematic liquid crystals, depending on the methanol content and dye concentration. The combination of the surface active-part and the azobenzene moiety would be responsible for the formation of the liquid crystal.     

Mesomorphic phase transitions of a series of D-phase compounds

Abstract

Mesomorphic phase transitions of 4′-n-alkoxy-3′-nitrobiphenyl-4-carboxylic acids (ANBC) with numbers of carbons (n) in the alkoxy group ranging from 11 to 22 have been studied by differential scanning calorimetry (DSC) and polarizing optical microscopy. The D phase, a mesophase of particular interest through its being optically isotropic, was observed for the n = 17, 19, 20, 21, and 22 members of the ANBCs, as well as for the n = 16 and 18 members, as reported previously. The S_c-D phase transition temperature decreased with increasing n, so that the temperature range of the D phase extended over 64° at n = 22. In the n = 15 member, the D phase was certainly observed on first heating, but was not seen on subsequent cooling and second heating processes.     

Inversion of the phase sequence between the cubic and smectic C phases under pressure

The phase behaviour of a thermotropic cubic mesogen of 1,2-bis(4′-n-tetradecyloxybenzoyl)hydrazine BABH-14 was studied under hydrostatic pressure using a polarising optical microscope equipped with a high-pressure optical cell, and the P–T phase diagram was constructed. BABH-14 shows the Cr–Cub–I transition sequence under atmospheric and lower pressures, but the Cub phase is replaced completely by the high-pressure SmC, SmC(hp), phase under higher pressures. There is a narrow intermediate-pressure region between the low- and high-pressure regions, in which the Cr–SmC(hp)–Cub–I phase sequence is recognised. The SmC(hp)–Cub transition line has a positive slope with pressure and there are two triple points: one is for the Cr, Cub and SmC(hp) phases and the other is for the I, Cub and SmC(hp) phases. Comparing the phase sequence of BABH-14 with those for BABH-8 and -10, the pressure-induced inversion of the phase sequence between the cubic and SmC phases occurs in the BABH-n homologous compounds. Another new phenomenon is the formation of the monotropic cubic phase on cooling in the intermediate- and high-pressure regions, and an intriguing phenomenon of the cubic phase appearing twice, i.e. I–Cub–SmC(hp)– Cub–Cr phase transition, occurs in the intermediate-pressure region.     

Hydration effect on the ion-pair extraction of lithium picrate by hydrophobic benzo-15-crown-5 ether into various less-polar diluents.

The ion-pair formation constant (K(MLA)(0) in mol(-1) dm(3)) for Li(B15C5)(+) with a picrate ion (Pic(-)) in water was determined by potentiometry with a K(+)-selective electrode at 25 degrees C and an ionic strength of 0, where B15C5 denotes benzo-15-crown-5 ether. Using the concentration equilibrium constants, K(MLA), estimated from this value, the extraction constants (mol(-2) dm(6) unit) of about ten diluents were re-calculated from previously reported extraction data. Also, the distribution constants of an ion-pair complex, Li(B15C5)Pic, between water and the diluents were re-estimated. A disagreement in the determined K(MLA) value between a solvent-extraction method and potentiometry was explained in terms of the Scatchard-Hildebrand equation; it came from the fact that the hydration of Li(I) in Li(B15C5)Pic was larger than that of free B15C5 in water. Then, the previously determined value by the former method was re-estimated using the potentiometric K(MLA) value.