
2: POLY( p-XYLYLENE)S 45
ammonium chloride, tetrabutyl ammonium bromide,
and benzyl triethyl ammonium chloride were used.
A molecular weight of 3 kDa was obtained.
2.3 Polymerization and Fabrication
A wide varietyof PPXshave beensynthesized, how-
ever only a few materials are commercially sold.
2.3.1 Chemical Vapor Deposition
One of the earliest methods for the preparation of
polymeric p-xylylene coatings is a high-temperature
pyrolysis of p -xylene at 800–1000
◦
C and subatmo-
spheric pressures, followed by cooling the pyrolysis
vapors to a polymerization temperature by condensing
the vapors on a cold surface [2,29]. During pyroly-
sis, reactive radicals