No abstract

Nitroxide-mediated polymerization (NMP) of N-(2methacryloyloxyethyl) pyrrolidone (MAEPYR) with 2-([tertbutyl[1-(diethoxyphosphoryl)-2,2-dimethylpropyl]amino]oxy)-2methylpropanoic acid (BlocBuilder) initiator and N-tert-butyl-N-[1-diethylphosphono-(2,2-dimethylpropyl)] (SG1) nitroxide permitted controlled synthesis of poly(N-(2-methacryloyloxyethyl)pyrrolidone-stat-9-(4-vinylbenzyl)-9H-carbazole) (poly(MAEPYRstat-VBK)) statistical copolymers. With at least 5 mol % VBK, the dispersity -D of the copolymers was below 1.4 at conversions less than 50%. At conversions higher than 50%, and at lower VBK feed content, there was a significant amount of termination reactions, which broadened the molecular weight distribution of the final polymers ( -D 5 1.4-2.3). The MAEPYR-rich statistical copolymers were subsequently tested for thermoresponsive behavior in aqueous media. The cloud point tempera-tures (CPTs) in aqueous solution were tuned by changing the VBK composition, solution concentration, and heating rate, and the transitions were thermally reversible with partial loss of reversibility at higher heating rates. The CPT decreased from 59.0 to 49.7 C with addition of only 1 mol % of VBK in the copolymer, and at more than 6 mol % VBK, the copolymer was water insoluble.

NANOCOMPOSITE On page 3506, Adriana C. Pinheiro, Adriana C. A. Casagrande, and Osvaldo L. Casa-grande, Jr., report linear low density polyethylene (LLDPE) nanocomposites containing different types of nanofiller (TiO 2 , MWCNT, expanded graphite, and boehmite) prepared with a tandem catalyst system composed of {Tp Ms }NiCl and Cp 2 ZrCl 2 with only ethylene as the monomer. Among the nanofillers utilized, carbon nanotubes and boehmite can nucleate LLDPE crystallization, as indicated by increased crystallization temperature. Furthermore, the presence of these nanofillers in the LLDPE matrix results in substantial improvement of the storage modulus as compared to neat LLDPE. The TEM images of LLDPE nanocomposites containing boehmite and MWCNT reveal homogeneous dispersion of these nanofillers into the LLDPE matrix. report on nanoparticles obtained after complexa-tion of Ru(NH 3) 3 Cl 3 with hydroxyl groups of dendritic copolymers of tert-butyl-glycidyl-ether and glycidol using silver tetrafluoroborate as a dechlorination agent. Visualization is performed by cryogenic transmission electron microscopy using a Libra 120 Zeiss microscope , operated at an acceleration voltage of 120 kV, at the Leibniz Institute of Polymer Research Dresden.

4‐acryloylmorpholine/4‐acryloylpiperidine statistical copolymers were synthesized by nitroxide mediated polymerization (NMP) with BlocBuilder unimolecular initiator in dimethylformamide solution at 120 °C. The copolymers had narrow molecular weight distributions (dispersity Đ = 1.25–1.35, number average molecular weights Mn = 8.5–13.7 kg mol−1). The copolymer microstructure was essentially statistical (reactivity ratios r4AP = 0.81 ± 0.73, r4AM = 0.73 ± 0.68 based on non‐linear fitting of the Mayo‐Lewis equation). Cloud point temperatures (CPT) in aqueous media were tuned from 11 °C to 92 °C, merely by adjusting the initial monomer composition. Using NMP permitted sharper control of the CPT transitions, compared to the similar copolymer made using conventional radical polymerization. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2160–2170

Low concentrations of 4-vinylphenylboronic acid (VPBA) were copolymerized with 2-N-morpholinoethyl methacrylate (MEMA) by nitroxide mediated polymerization using BlocBuilder TM unimolecular initiator at 80 to 90 8C. The MEMA/VPBA copolymerizations were performed at initial feed compositions (f VPBA,0 ) of 0.05 to 0.10 VPBA, with f VPBA,0 5 0.10 using dimethylacetamide (DMAc) solvent being most effective, as seen by a linear increase in number average molecular weight, M n , versus conversion and low dispersity, -D < 1.40. The copolymers were further chain-extended with a second batch of VPBA, resulting in a block copolymer with monomodal molecular weight distribution and -D 5 1.66. For MEMA/VPBA copolymers, increases in VPBA composition and polymer solution concentration resulted in decreases in the cloud point temperature (CPT, typically varied between 27.4-37.8 8C) and CPT increased from 31.2 to 33.8 8C to about 88 8C with decreases in pH from 7 to 4. Rheological tests with small angle light scattering (SALS) confirmed CPTs measured by UV-Vis and DLS. These copolymers were targeted as models to combine possible glucose-sensing boronic acid functionality the thermoresponsiveness provided by MEMA groups. V C 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016Chem. , 54, 1560Chem. -1572

A series of random copolymers and block copolymers containing water‐soluble 4AM and fluorescent VAK are synthesized by NMP. The homopolymerizations of 4AM and VAK and 4AM/VAK random copolymerization are performed in 50 wt% DMF using 10 mol% SG1, resulting in a linear increase in $\overline {M} _{{\rm n}} $ versus conversion, and final polymers with narrow molecular weight distributions ($\overline {M} _{{\rm w}} /\overline {M} _{{\rm n}} $ < 1.4). Reactivity ratios rVAK = 0.64 ± 0.52 and r4AM = 0.86 ± 0.66 are obtained for the 4AM/VAK random copolymerization. In addition, a poly(4AM) macroinitiator is used to initiate a surfactant‐free suspension polymerization of VAK. After 2.5 h, the resulting amphiphilic block copolymer has $\overline {M} _{{\rm n}} $ = 12.6 kg · mol−1, $\overline {M} _{{\rm w}} /\overline {M} _{{\rm n}} $ = 1.48, molar composition FVAK = 0.38 with latex particle sizes between 270 and 475 nm.