Poly(p-xylylene)(PPX)prepared by chemical vapor deposition(CVD)polymerization shows promising features like absolute conformation to substrate topology

pinhole—free coverage even in ultrathin films

the ability to penetrate and cover complex geometries

and extraordinarily high chemical inertness and purity compared to common polymer coatings．However

the exploitation of[2．2]paracyelophanes for generating functionalized surfaces is interesting．The funetional groups may be useful for further modifications．Poly(carboxyl—P—xylylene—co-p—xylylene) (PPX-carb) was prepared by CVD polymerization in present work．The chemical structure of the resulted polymer was confirmed by FTIR and elemental analysis．It is indicated that PPX—carb membrane has good solvent resistant and high chemical oxidation resistant．Thermogravimetrie analysis(TGA)

differential scanning calorimetry(DSC)

and dynamic mechanical analysis(DMA)were used to study the thermal properties of PPX—carb membranes．It is found that the initial degradation temperature and Tg of PPX-carb membranes are reduced with the introduction of carboxyl group as side groups

while the degradation temperature of the main chain of PPX-carb is higher than that of PPX．With the introduction of carboxyl

the polymer becomes amorphous

and the softness as well as the dynamic mechanical damping pmporties of PPX—carb are improved．The hydrophilieity and vapor permeability of PPX-carb membranes are also improved．