Polymer Chemistry Blog

Polyisoprene (PI) is an interesting backbone material for graft copolymer synthesis. Isoprene can be renewably sourced and polymerized through a variety of methods. Hydroxyl functionalized PI is interesting as it allows for the synthesis of polylactide graft copolymers with a rubbery backbone, which can be quite tough materials as compared to the brittle poly(lactic acid) (PLA) homopolymer. In an effort to develop a hydroxyl functionalized PI macroinitiator, the authors investigated RAFT copolymerizations of isoprene with 2-methylenebut-3-en-1-ol (IOH) and with commercially available, hydroxyl containing monomers 2-hydroxyethyl acrylate (HEA) and 2-hydroxyethyl methacrylate (HEMA). The monomer IOH, structurally similar to isoprene, exhibited favorable kinetics towards copolymerization and copolymerized with isoprene in a rather random manner, producing P(I-co-IOH) macroinitiators with hydroxyl content close to that which was fed into the system. Additionally, IOH was copolymerized with isoprene in an emulsion process at room temperature. The hydroxyl containing isoprene copolymers were also able to undergo subsequent reactions efficiently to produce PLA graft copolymers.

The world market for nonvolatile memory devices has grown rapidly as the demand for mobile devices has increased. The high-performance polymers based on aromatic polyimides (PIs) under development yield many advantages and several PIs have been introduced as the active materials in nonvolatile memory devices. The authors reported here the effects of substituents on the electrical memory characteristics of poly(4,4′-aminotriphenylene hexafluoroisopropylidenediphthalimide) (6F-TPA PI) analogs prepared from two different triphenylamine (TPA) derivatives. These PIs exhibited various types of memory behavior, namely, unipolar WORM and ON/OFF switching-type memory and bipolar ON/OFF switching type memory, depending on the incorporated substituents. The underlying switching mechanism was investigated, and the interfaces between the PI films and the metal electrodes in devices were examined.

Single electron transfer-living radical polymerization (SET-LRP) has been recently proposed as a “variant” of the originally-developed atom transfer radical polymerization (ATRP). There has been very little research done, however, combining SET-LRP with reducing agents. In this view, Cunningham and co-workers reported an innovative design for a flow reactor for the continuous production of uniform polymer with high livingness using SET-LRP, improving upon the initial concept. Instead of using copper tubing to construct the entire reactor, a short copper coil was used to initiate polymerization and generate soluble copper species. The bulk of the reaction then took place in inert stainless steel tubing, using ascorbic acid as a reducing agent to drive the catalytic cycle and mediate the polymerization. Polymerizations were conducted at ambient temperature with 30 wt% DMSO as solvent, producing well defined living polymer at a steady state conversion of 78% for a residence time of 62 min. Chain extensions using outlet polymer solutions were well-controlled and proceeded to high conversion in a short period of time, with a final concentration of 10 ppm of residual copper. The results illustrate the significant potential of using a continuous tubular reactor with ascorbic acid as a reducing agent as an efficient means to scale-up production of well controlled polyacrylics and other multiblock copolymers.

The specific recognition of targeting glucose moieties and antioxidant ability of GSH make peptide–glycopolymer bioconjugate PGlcEMA-GSH a suitable candidate for antioxidant delivery systems, biomimetics and biodetection.

This approach appeared here to be extremely robust for the preparation of a broad range of cyclic block copolymers with tailored ring morphology and functionalities.