| Abstract: | Advancing and receding contact angles on paraffin (PF) and poly(methyl methacrylate) (PMMA) have been measured for solutions of hydroxypropyl cellulose (HPC) and hydroxycthyl cellulose (HEC), two hydrophohic polymers differing considerably in their surface activity at the air-water interface. Consistent with observations made previously with hydrocarbon-chain surfactant solutions, advancing contact angles with PF are the same as those observed with pure liquids having the same surface tension, while those with PMMA are considerably greater. Receding contact angles for these polymer solutions appear to he the same as those observed with pure liquids. Consequently, this leads to less wettability in an advancing mode and greater apparent contact angle hysteresis than might be expected. Concurrent studies of HPC and HEC adsorption with the same PMMA samples used in the wetting studies and estimates of adsorption of HPC and HEC at the air-water interface indicate that these effects on wetting are due primarily to greater nonspecific polymer adsorption to the air-water interface than to the more polar PMMA-water interface. |
