含氟丙烯酸酯聚合物乳胶膜表面性质

采用XPS和界面张力仪分别测定了含氟丙烯酸酯聚合物乳胶膜表面的组成及水在其表面的动态接触角, 并用状态逼近方程模型计算了含氟聚合物乳胶膜的表面张力, 考察了温度对乳胶膜润湿性的影响. 结果表明, 含氟聚合物乳胶膜表层较深处的F 1s信号强度比近表面要弱, 乳胶膜表面张力随表面氟原子浓度增加在一定程度上呈现线性下降；含氟侧链(Rf)较长(碳原子数n＞6)的含氟聚合物, 其表面张力随Rf单元含量增加而下降的趋势显著高于Rf较短(n≤6)的含氟聚合物, 而水在含氟聚合物乳胶膜表面上的后退接触角θr随n增大出现急剧上升, n≥10 时, θr值几乎恒定不再随n增大而改变. 此外, 参与共聚的非氟丙烯酸酯酯基碳链较短时, 水在共聚物乳胶膜表面的θr随氟单元含量增加而增加的趋势更显著；温度超过40 ℃后, 水对聚合物乳胶膜的润湿性随温度上升略有改善.

Surface Properties of Fluorinated Acrylate Polymers Latex Films

The surface chemical compositions of fluorinated latex films and the dynamic contact angle of water were determined using X-ray photoelectron spectroscopy (XPS) and a Krüss interface tension measurement, respectively. The surface tensions of the films were calculated by the equation of state approach using the dynamic contact angles, and the effect of temperature on the wetting behavior of these films was investigated. It was shown that the F 1s signal intensity from the outermost surface of these fluorinated latex films was stronger than that from the interior surface of the film and that the surface tension showed a linear decrease with the increase of density of fluorine atom on the latex film surface to a certain extent. The surface tensions rapidly decreased with the increase of fluorinated lateral chains (Rf) content in the copolymer with longer Rf (carbon atomnumber n＞6). The water receding contact angles (θr) on the latex films sharply decreased with the increase of n value, leveled off nearly at n=10, and almost remained unchanged when n＞10. In addition, θr increased more remarkably with the increase of F content in the poly (protonated acrylate-co-fluorinated acrylate) with shorter hydrocarbon side chains. The water wetting ability of the fluorinate latex films became slightly better only when temperature was more than 40 ℃.