Radical polymerization procedure

NMP of S in heterogeneous media is discussed in reviews by Qiu et at.,205 Cunningham,206 207 and Schork et a/.208 There have been several theoretical studies dealing with NMP and other living radical procedures in emulsion and miniemulsion."09 213 Butte et nr/.210 214 concluded that NMP (and ATRP) should be subject to marked retardation as a consequence of the persistent radical effect. Charlcux209 predicted enhanced polymerization rates for minicmulsion with small... 

Dynamic formation of graft polymers was synthesized by means of the radical crossover reaction of alkoxyamines by using the complementarity between nitroxide radical and styryl radical (Fig. 8.13) [40]. Copolymer 48 having alkoxyamine units on its side chain was synthesized via atom transfer radical polymerization (ATRP) of TEMPO-based alkoxyamine monomer 47 and MMA at 50°C (Scheme 8.9). The TEMPO-based alkoxyamine-terminated polystyrene 49 was prepared through the conventional nitroxide-mediated free radical polymerization (NMP) procedure [5,41], The mixture of copolymers 48 and 49 was heated in anisole... 

The potential for surface-initiated polymerizations using nitroxide-mediated living free radical procedures is perhaps best illustrated by the direct synthesis of dispersed nanocomposities by Sogah and Giannelis.212 In this approach the synthetic versatility of the alkoxyamine group is again exploited to... 

It can be formed by suspension polymerization. One procedure is to carry out the reaction in an aqueous solution of lithium bromide at -25 °C with magnesium carbonate as the suspending agent. No initiator is added and the reaction takes about 20 hours. Because the reaction is inhibited by hydroquinone and accelerated by ultraviolet light, it is believed to take place by a free-radical mechanism. Whether it is chain-growth polymerization, however, is not certain. A1 1 copolymer is always formed regardless of the composition of the monomer feed, and the copolymerization takes place only at low temperatures. At elevated temperatures, however, cyclic oxazetidines form instead ... 

Most of the MIPs are fashioned through the free-radical polymerization (FRP) procedures that are initiated upon the decomposition of a radical producing compound, referred to as the initiator, by means of thermal or photochemical stimuli. Such reactions are commonly conducted imder mild temperature and pressure conditions. The FRP is appropriate for a variety of functional monomers and templates [28]. According to the general pattern of free-radical reactions, after the initiation phase, the number of the free radicals increases, leading to the propagation stage where the main portion of... 

A commercially available monomer that is structurally related to 2-methylene-oxetane is ketene dimer. However, almost nothing has been reported concerning its polymerization by free radical procedures. When ketene dimer was heated with di-Jt-butyl peroxide at 130° in a sealed tube, a small pressure built up and the resulting polymer consisted of mostly 1,3-diketone units. When the pol3nneriza-tion was carried out in a solvent at atmospheric pressure, carbon monoxide was liberated and a copol3nner consisting of mainly monoketone units was obtained. 

Trilialophenols can be converted to poly(dihaloph.enylene oxide)s by a reaction that resembles radical-initiated displacement polymerization. In one procedure, either a copper or silver complex of the phenol is heated to produce a branched product (50). In another procedure, a catalytic quantity of an oxidizing agent and the dry sodium salt in dimethyl sulfoxide produces linear poly(2,6-dichloro-l,4-polyphenylene oxide) (51). The polymer can also be prepared by direct oxidation with a copper—amine catalyst, although branching in the ortho positions is indicated by chlorine analyses (52). 

One of the key benefits of anionic PS is that it contains much lower levels of residual styrene monomer than free-radical PS (167). This is because free-radical polymerization processes only operate at 60—80% styrene conversion, whereas anionic processes operate at >99% styrene conversion. Removal of unreacted styrene monomer from free-radical PS is accompHshed using continuous devolatilization at high temperature (220—260°C) and vacuum. This process leaves about 200—800 ppm of styrene monomer in the product. Taking the styrene to a lower level requires special devolatilization procedures such as steam stripping (168). 

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