Chain-growth polymerization nonionic monomers

A historical perspective on the development of hydrophobe-modified, water-soluble polymers is presented. The various synthetic procedures used to obtain different associative thickeners are discussed in terms of the complexities in ionogenic monomer polymerizations. This discussion serves two purposes. The first is to present the peculiarities in anionic and cationic polymer synthesis in contiguity with previous work on water-soluble polymers that related only to their use. The second purpose is to draw parallels between the discontinuities in the classical chain-growth polymerization of nonionic with ionogenic monomers and those that should be expected to occur with hydrophobe-modified monomers, but for which there are insufficient data in associative thickener technology to define properly. 

Homopolymerization. Nonionic Monomers. The chain-growth polymerization of vinyl monomers occurs via a three-part mechanism initiation, propagation, and termination. Under steady-state conditions, the rate of polymerization (R ) is defined (21-24) by equation 1 ... 

The mechanism of the anionic polymerization of lactams has been studied mainly for CL-the most easily accessible (and industrially produced) lactam. The basis for the mechanism of anionic polymerization of lactams is fixed [5, 12-14], and differs from conventional anionic polymerization. The process involves addition of the monomeric lactam anion (the so-called anionically activated monomer ) onto a nonionic growth center located at the end of the growing chain. Thus, lactam anion 2 is formed by the reachon of a proper nucleophile with lactam 1 (Equation 7.1) ... 

Thus, the initiation system of the activated polymerization has two components anionicaUy activated monomer (lactam salt) or its precursor are denoted nonuni-formly in the literature as, for example, the initiator, catalyst or activator similarly, the source of the nonionic growth center is called the promoter, catalyst, cocatalyst, chain initiator, initiator, coinitiator, activator, accelerator, and so on. In this chapter, the combined term initiator/activator wUl be used. 

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