Chain transfer kinetics of acid/base switchable n-aryl- n-pyridyl dithiocarbamate RAFT agents in methyl acrylate, n-vinylcarbazole and vinyl acetate polymerization

This is an accepted manuscript of an article published by American Chemistry Society in Macromolecules on 14/05/2012, available online: https://doi.org/10.1021/ma300616g ©American Chemical Society. The accepted version of the publication may differ from the final published version.The structures of the "Z" and "R" substituents of a RAFT agent (Z-C(S)S-R) determine a RAFT agent's ability to control radical polymerization. In this paper we report new acid/base switchable N-aryl-N-pyridyl dithiocarbamates (R = -CH 2CN, Z = -N(Py)(Ar)) which vary in substituent at the 4-position of the aryl ring and the use of these to control molecular weight and dispersity. In their protonated form, the new RAFT agents are more effective in controlling polymerization of the more activated monomer, methyl acrylate (MA), whereas in their neutral form they provide more effective control of the polymerization of less activated monomers, N-vinyl carbazole (NVC) and vinyl acetate (VAc). For each polymerization, the apparent chain transfer coefficient (C trapp) shows a good correlation with Hammett parameters. Dithiocarbamates with more electron-withdrawing aryl ring substituents have the higher C trapp. This demonstrates the influence of polar effects on C trapp and supports the hypothesis that the activity of these RAFT agents is determined by the availability of the lone pair of the dithiocarbamate nitrogen.The authors gratefully acknowledge the Capability Development Fund of CSIRO Materials Science and Engineering for financial support.Published versio

Reverse thermo-responsive polymers for sustained delivery

Delivery of a therapeutic agent where needed in vivo (on site) at the required dose is a key issue faced in a number of interventions. Effective strategies to resolve this offer significant benefits, one of the key advantages being the use of lower doses compared to traditional administration methods such as in oral capsules or intravenus injections. This advantage coupled with sustained release of the agent on site at the required level over a long period of time eliminates the need for repeated interventions and set new standards in drug delivery technolgies. Such novel strategies lead to significant economic benefits, less toxic after effects (use of lower doses), minimal organ damage and most importantly less trauma to the patient. CSIRO has developed a series of aqueous polymer solutions capable of encapsulating a range of therapeutic agents, that are injectable through a fine needle, and form instantaneous gels at physiological temperatures

Formation of tethered polyacrylic acid loops in core-shell micelles

Well-defined amphiphilic four-arm star P(AA-b-STY) block copolymers have been dispersed in water to form core-shell micelles in which the shell consists of tethered PAA loops. The entropic penalty for having such loops resulted in a less densely packed PSTY core when compared to linear diblock copolymers of the same arm length. The surface of the shell is irregular because of the tethering points, but when cleaved the PAA chains extend to form a regular and relatively uniform corona