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In this work, a cationic star polymer [poly(2-dimethylamino)ethyl methacrylate (PDMAEMA)] was prepared via atom transfer radical polymerization (ATRP), using brominated calix[4]resorcinarene as an initiator. Hydrophobic moieties, methyl methacrylate (MMA) and butyl acrylate (BA), were further incorporated via "one-pot" method. Well-defined eight-armed star block copolymers bearing hydrophilic blocks inside and hydrophobic blocks outside were synthesized. The molecular weight, particle size, electrophoretic mobility and apparent charge density were determined by gel permeation chromatography (GPC), dynamic light scattering (DLS), phase analysis light scattering (PALS) and colloidal titration, respectively. The zeta potentials and apparent charge densities of the products exhibited the characteristics of polyelectrolyte. The incorporation of hydrophobic moieties generated electrostatic screening effect. The as-synthesized amphiphilic star copolymer is promising as a thermo-sensitive gene carrier for gene therapy., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The alkyl‐terminated poly(hexamethyleneguanidine hydrochloride) (PHMG‐L), which is antibacterial by physical membrane rupture, was selected as the functional gene, a nonleaching antimicrobial polymethyl methacrylate (PMMA) was developed by the melting grafting reaction between the random copolymer P (MMA‐co‐MAH) containing 5.0 wt% maleic anhydride (MAH) and the PHMG‐L. The results of Fourier transform infrared spectroscopy, X‐ray photoelectron spectra, energy spectrometer, atomic force microscope, scanning electron microscopy, elemental analyzer, UV–visible spectrophotometer confirmed that P(MMA‐g‐PHMG) had been successfully prepared, and the grafting efficiency was at 67.1%–70.7% while 1.0–3.0 wt% PHMG‐L was added. Furthermore, P(MMA‐g‐PHMG) was compatible with PMMA, and partially enriched on the surface of the mixture. The inhibition rates of antimicrobial PMMA with 3.0 wt% PHMG‐L against Escherichia coli and Staphylococcus aureus reached 99.9%, and the nonleaching characteristic ensured the safety and long‐term antimicrobial property. The antimicrobial PMMA also possessed excellent heat resistance and transparency. This study provides a green and promising approach for the industrial fabrication of antimicrobial PMMA. [ABSTRACT FROM AUTHOR]

In order to break through the bottleneck of anionic polymerization, polar monomers such as methyl methacrylate (MMA), ethyl methacrylate, butyl methacrylate, and hexyl methacrylate are subjected to anionic polymerization at room temperature in tetrahydrofuran (THF) using potassium tert‐butoxide (t‐BuOK) as the initiator. The polymerization of alkyl methacrylates is studied by multidetector gel permeation chromatography, proton nuclear magnetic resonance (1H‐NMR) and 13C‐NMR spectroscopy, and dynamic laser light scattering. It is found that t‐BuOK can initiate the living anionic polymerization of polar alkyl methacrylate, and the polymerization conversion almost reaches up to 100%. t‐BuOK exists into two kinds of agglomerates, whose hydrodynamic volumes are 10 and 80 nm, respectively. t‐BuOK in THF is similar to emulsion and has a critical active species concentration of about 0.0265 mol L−1 and does not depend on how much t‐BuOK is added. After the initiation of the polymerization, the large agglomerates of a loose and less regular structure that have occupied the main part of t‐BuOK are greatly reduced, but they do not continue to decrease until they disappear according to the equilibrium theory. Similarly, the active chain after initiation also will not aggregate again. Furthermore, t‐BuOK also has an active species with smaller average vibration size between cation and anion pairs, which can only initiate the polymerization of MMA with rather slow rate but cannot initiate other alkyl methacrylates. At last, because t‐BuOK can make the dormant species caused by side reactions to be revived, the anionic polymerization of MMA could obtain a high yield. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1130–1139 [ABSTRACT FROM AUTHOR]

Initiating Mechanism of the Anionic Polymerization of Methacrylates with t-BuOK and the Synthesis of ABA Type Triblock Copolymers B Back Cover b : In article number 1900390, Anna Zheng, Yong Guan, and co-workers report that using I t i -BuOK as initiator, an ABA-type triblock copolymer (PMMA-b-PLMA-b-PMMA) is synthesized at 0 °C without using any sidereaction inhibitors and the monomer conversion is over 97%, which paves the way for the synthesis of thermoplastic elastomers with full polar monomers and full saturated chains by anionic polymerization. [Extracted from the article]

• The Trommsdorff effect was weakened and postponed under higher shear rate. • Increasing shear rate significantly enhanced the chain initiation rate(R i) • The Trommsdorff effect occurred at a critical viscosity about 1000 ± 100 Pa·s. • The Trommsdorff effect was effectively utilized during reactive extrusion of PMMA. In this study, a concentric-cylinder and double-walled reactor accurately controlling shear rates was established to conduct the free radical bulk polymerization of methyl methacrylate, and the kinetics of Trommsdorff effect under constant shear was investigated. The results showed that increasing shear rate significantly enhanced the termination rate constant (k t), and thus effectively weakened and postponed the Trommsdorff effect. However, the polymerization rate during the "quasi-steady state" was almost not affected by shear rate. Differing from the classical theory, the chain initiation rate (R i) also increased with shear rate, which was due to the improving initiation efficiency of polymerization reaction. On the other hand, it was found that the critical viscosity when Trommsdorff effect occurred was about 1000 ± 100 Pa·s, independent of shear rates, temperatures and initiator concentrations. Based on utilizing the Trommsdorff effect, polymethyl methacrylate (PMMA) was further synthesized via reactive extrusion, with superior performance comparing to commercial product. [ABSTRACT FROM AUTHOR]