ABSTRACT
Whether or not the surface of a polymer is hydrophilic or hydrophobic is not determined by whether hydrophilic or hydrophobic moieties exist in a polymer molecule but by what kind of moieties actually occupy the top surface of the polymer. Namely, the surface properties are controlled by the surface configuration but not by the configuration of polymer molecules. The configuration of PVA can be represented by –[CH2-CH(OH)]n-, which indicates that the polymer is highly hydrophilic, and PVA is water soluble. However, the surface characteristics of a film of PVA depend entirely on how many OH groups exist on the top surface or buried in the bulk phase of the polymer that is described by the surface configuration.
