Controlled/living polymerizations

Phosphoranyl radicals can be involved [77] in RAFT processes [78] (reversible addition fragmentation transfer) used to control free radical polymerizations [79]. We have shown [77] that tetrathiophosphoric acid esters are able to afford controlled/living polymerizations when they are used as RAFT agents. This result can be explained by addition of polymer radicals to the P=S bond followed by the selective p-fragmentation of the ensuing phosphoranyl radicals to release the polymer chain and to regenerate the RAFT agent (Scheme 41). 

The development of controlled/living radical polymerization processes, yielding polymers with narrow polydispersities and a high percentage of liv-... 

In recent years, much attention has been paid to the use of controlled/ living polymerizations from flat and spherical surfaces [121,122],because this allows better control over the MW and MWD of the target polymer. By using these techniques, a high grafting density and a controlled film thickness can be obtained, as such brushes consist of end-grafted, strictly linear chains of the same length and the chains are forced to stretch away from the flat surface. Several research... 

Controlled/living radical polymerisation (CRP) is currently a fast developing area in polymer synthesis and it allows preparation of many advanced polymeric materials, including thermoplastic elastomers, surfactants, gels, coatings, biomaterials, materials for electronics and many others. 

A similar in situ approach to alkoxide formation employs the readily accessible tris(amide)-Y(NTMS2)3, (293), and PrOI 1.881 In the absence of alcohol the polymerization of CL is fast but not controlled (Mw/Mn > 3). However, upon addition of alcohol, a controlled living system with polydispersities 1.1-1.2 results. At least 50 equivalents of PrOH may be added (the excess effects rapid chain transfer) with molecular weights in good agreement with theoretical values. Similar results have been reported using Nd(NTMS2)3, (294), and PrOH.882 The reactions of PrOH with (292) and (293) have both been studied by NMR, and in both cases Y5(/r5-0)(0 Pr)13 is not... 

Additionally, research on FI catalysts has provided useful information on high catalytic activity, the formation of highly syndiotactic PPs with C2-symmetric catalysts, the origin of highly controlled living olefin polymerization, and the high incorporation capability for higher a-olefins. 

In 1995, a new class of controlled/ living radical polymerization methods was reported by the groups of Matyjaszewski [34] and Sawamoto [35], This new process, named atom transfer radical polymerization (ATRP) [34], has had a tremendous... 

Pyun, J. Xia, J. Matyjaszewski, K. Organic-Inorganic Hybrid Materials from Polysiloxanes and Polysilsesquioxanes Using Controlled/ Living Radical Polymerization. In Synthesis and Properties of Silicones and Silicone-Modified Materials Clarson, S. J., Fitzgerald, J. J., Owen, M. J., Smith, S. D., Van Dyke, M. E., Eds. ACS Symposium Series 838 American Chemical Society Washington, DC, 2003 pp 273—284. 

Figure 2.44. Hypothetical scheme for TEMPO controlled "living" radical polymerization...

K. Matyjaszewski, In Controlled/Living Radical Polymerization Matyjaszewski,... 

The use of several diorganyl tellurides as initiators for controlled living radical polymerization of styrenes has been investigated. " ... 

Becer CR, Schubert US (2009) Parallel optimization and high-throughput preparation of well-defined copolymer libraries using controlled/ living polymerization methods. Adv Polym Sci DOl 10.1007/12 2009 16... 

Parallel Optimization and High-Throughput Preparation of Well-Defined Copolymer Libraries Using Controlled/ Living Polymerization Methods... 

Abstract This chapter highlights the application of controlled/ living polymerization (CLP) techniques in automated parallel synthesizers for both optimizing reaction parameters as well as preparing copolymer libraries. Special attention is given to the use of CLP techniques for constructing well-defined copolymer libraries. Furthermore, alternative strategies for the preparation of block copolymer libraries are discussed. 

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