RAFT polymerization of activated 4-vinylbenzoates

Influence of Backbone on the Performance of Pendant Polymer Electrode Materials in Li-ion Batteries

Pendant polymers are a promising class of electrode materials due to their synthetic simplicity, derivation from sustainable feedstocks, and potentially benign synthesis. These materials consist of a redox-active pendant tethered to a polymer backbone, which mitigates dissolution during electrode cycling. To date, an extensive number of pendant groups have been studied within the context of metal-ion batteries. However, the choice of the polymer backbone and its impact on the electrode performance have been relatively understudied. In this work, we use a postpolymerization modification approach to synthesize a series of viologen-bearing redox-active pendant polymers with similar molecular weights but three distinct chemical backbones, namely, polyacrylamide, polymethacrylamide, and polystyryl. By evaluating the polymers in lithium-ion batteries, we show that the polymer backbone has a significant influence on electrode performance and behavior. Specifically, the polymethacrylamide displays slower kinetics than the other two polymers, resulting in lower capacities, particularly at high cycling rates. Furthermore, the charge storage mechanism is dependent on the nature of the backbone: the polyacrylamide shows a significant capacitive contribution to charge storage, while the polystyryl does not. The difference in performance between the polymer electrode materials is ascribed to a difference in chain mobility and packing within the electrode films. Overall, this work shows that the fundamental properties of the polymer backbone are critical to the design of high-performance polymer electrodes.

Visible-light-induced synthesis of polymers with versatile end groups mediated by organocobalt complexes

Synthesis of polymers with well-defined functional groups at α and ω ends by using carefully designed organocobalt complexes has been accomplished.

Folate conjugation to polymeric micelles via boronic acid ester to deliver platinum drugs to ovarian cancer cell lines

In this study, a novel technique was used for the reversible attachment of folic acid on the surface of polymeric micelles for a tumor-specific drug delivery system. The reversible conjugation is based on the interaction between phenylboronic acid (PBA) and dopamine to form a borate ester. The conjugation is fast and efficient and in vitro experiments via confocal fluorescent microscopy show that the linker is stable in for several hours. Reversible addition-fragmentation chain transfer (RAFT) polymerization was used to synthesize two various sized water-soluble block copolymer of oligoethylene glycol methylether methacylate and methyl acrylic acid (POEGMEMA(35)-b-PMAA(200) and POEGMEMA(26)-b-PMAA(90)). The platinum drug, oxoplatin, was then subsequently attached to the polymer via ester formation leading to platinum loading of 12 wt % as determined by TGA. The platinum-induced amphiphilic block copolymers that consequently led to the formation of micelles of sizes 150 and 20 nm in an aqueous environment with the longer PMAA block forming larger micelles. The small micelles were in addition cross-linked using 1,8-diaminooctane to further stabilize their structure. The targeting ability of folate conjugated polymeric micelles was investigated against two types of tumor cell lines: A549 (-FR) and OVCAR-3 (+FR). The cell line growth inhibitory efficacy of material synthesized was evaluated by using SRB method. The results revealed that folate conjugated micelles showed higher activity in FR + OVCAR-3 cells but not in FR - A549 cells. Similar results were obtained for both small and large micelles without the conjugation of folate. Comparing large and small micelles it can be observed that larger micelles are more efficient, which has been attributed to the lower stability of the smaller micelles. Micelle stabilization via cross-linking could indeed increase the toxicity of the drug carrier.

Living Radical Polymerization by the RAFT Process - A Second Update

This paper provides a second update to the review of reversible deactivation radical polymerization achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of reversible addition–fragmentation chain transfer (RAFT) that was published in June 2005 (Aust. J. Chem. 2005, 58, 379–410). The first update was published in November 2006 (Aust. J. Chem. 2006, 59, 669–692). This review cites over 500 papers that appeared during the period mid-2006 to mid-2009 covering various aspects of RAFT polymerization ranging from reagent synthesis and properties, kinetics and mechanism of polymerization, novel polymer syntheses and a diverse range of applications. Significant developments have occurred, particularly in the areas of novel RAFT agents, techniques for end-group removal and transformation, the production of micro/nanoparticles and modified surfaces, and biopolymer conjugates both for therapeutic and diagnostic applications.