Chemical vapor deposition liquid phase polymerization

The techniques of graft polymerization have been developed for liquid as well as gas phase. One of the polymerization techniques comprises impregnation of cellulose by a solution of conjugated monomers, followed by soaking in a relevant initiator. Chemical vapor deposition (CVD) of poly(3,4-ethylenedioxythiophene) is another, solvent-less technique, used for thin layer deposition of conjugated polymer on fibers [33]. Three CVD methods have been developed physical vaporization CVD [34, 35], plasma-enhanced CVD [36], and thermally initiated CVD [37, 38]. However, low conductivity is achieved when dopants are not used. 

One of the primary differences between CVD (or in the case of polymers, commonly referred to, as chemical vapor polymerization or CVP) and other conventional deposition techniques, particularly for polymer thin films, is that CVD is a dry process. There is no liquid intermediate between the gas phase reactants and the resultant solid thin film and thus, problems due to surface tension such as pulling away from the corners, sharp edges etc, are not present. Additionally, CVD enables deposition of uniform thin films in recesses, holes and other difficult three dimensional configurations unlike solution based techniques which are limited to planar substrates. In the terminology of thin film device fabrication, CVD films have excellent gap-filling and step coverage characteristics. 

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