Transport polymerization

Transport polymerization has also been studied with other monomers, including methylene and other carbenes (phenylcarbene, 1,4-phenylenecarbene), silylenes such as Si2 and germy-lenes such as GeCl2 and Ge2 [Lee, 1977-1978 lee and Wunderlich, 1978]. 

Ball JM, Moldoveanu Z, Melsen LR, et al. A polarized human endometrial cell line that binds and transports polymeric IgA. In Vitro Cell Dev Biol Anim 1995 31(3) 196-206. 

The 4-(4-(hexyloxy)phenyl)-3,5-diphenyl-4H-1,2,4-triazole moiety can be used in electron transporting polymeric segments and shows electroluminescence in poly(p-phenylene vinylene) (PPV) derivatives. 

The molecular weights of these polymers were estimated to be as high as 500,000. The total process is sometimes called transport polymerization. Poly(p-xylylene) films are produced commercially. The value of Tm for this polymer, which is crystalline, is 400 °C and it carries the trade name of Parylene. Films of poly(p-xylylene) have only fair thermal stability and are brittle, but exhibit good chemical resistance and are very good electrical insulators. Pyrolysis of xylene in steam at 950 °C yields the dimer intermediate. The yield is reported to be 15%. ... 

Discuss transport polymerization and explain how it is currently practiced commercially. 

The main issue in condensation polymerization is the retention of equivalent concentrations of both contra-functional groups (COOH and NH2), because an excess of either one eventually decreases the chain length significantly. Hence it is customary to react both monomers in a first stage forming a Nylon salt (hexa-methylene diammonium adipate) as an aqueous solution which is conveniently stored or transported. Polymerization is carried out in a stirred tank (autoclave), either batchwise or continuously, at pressures up to 20 atmospheres and temperature of 200 C to 275 C. 

C. J. Lee, Transport polymerization of gaseous intermediates and polymer crystals growth, J. 

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