Abstract
A considerable amount of the worldwide industrial production of synthetic polymers is currently based on radical polymerization methods. The steadily increasing demand on high performance plastics and tailored polymers which serve specialized applications is driven by the development of new techniques to enable control of polymerization reactions on a molecular level. Contrary to conventional radical polymerization, reversible-deactivation radical polymerization (RDRP) techniques provide the possibility to prepare polymers with well-defined structures and functionalities. The review provides a comprehensive summary over the development of the three most important RDRP methods, which are nitroxide mediated radical polymerization, atom transfer radical polymerization and reversible addition fragmentation chain transfer polymerization. The focus thereby is set on the newest developments in transition metal free systems, which allow using these techniques for biological or biomedical applications. After each section selected examples from materials synthesis and application to biomedical materials are summarized.
Highlights
Conventional radical polymerization was already a widespread technique when Swarcz introduced the concept of living anionic polymerization for the first time in 1956 [1] and demonstrated its viability for the fabrication of block copolymers [2]
nitroxide mediated radical polymerization (NMRP) shows all typical features of a living polymerization reaction and tuning the alkyl as well as the nitroxide fragment in the unimolecular initiator allows for preparation of α- and ω-end-functionalized polymers
We reported the successful photo-induced metal free Atom Transfer Radical Polymerization (ATRP) using highly conjugated thienothiophene derivatives
Summary
Conventional radical polymerization was already a widespread technique when Swarcz introduced the concept of living anionic polymerization for the first time in 1956 [1] and demonstrated its viability for the fabrication of block copolymers [2]. A low degree of termination reactions is necessary These criteria are met by a dynamic equilibrium between a dormant and an active state which can be enabled by trapping radical chains with stable radicals or by reversible transfer processes. In degenerative exchange chain transfer (DT, Scheme 1b) the dormant polymer is attracted by a propagating radical to form the active species and the dormant species, P–X. Two catalytic pathways exist to establish a dynamic equilibrium: In reversible chain transfer polymerization (RCTP, Scheme 1d) iodine complexes of Ge, Sn, N or P compounds (AI) mediate as catalysts the abstraction of capping iodine from dormant polymer species to form a complex A . Decreasing the degree of polymerization (DPT), conversion (p) or rate coefficients of termination (kt) to propagation (kp) as well as increasing monomer concentration [M]0 and reaction time (t) results in decreased DCF and increased chain end-functionality. Polymers obtained by NMRP do not require additional purification steps
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
