PS-b-PAA嵌段共聚物包覆碳酸钙的表界面性质和机理研究

The study on Mechanism, Interfacial Properties of PS-b-PAA Copolymer Coated Calcium Carbonate Particulate

通过聚苯乙烯-丙烯酸嵌段共聚物(PS-b-PAA)包覆碳酸钙系列样品的溶解曲线,结合近红外光谱和XPS推断得到了PS-b-PAA分子与碳酸钙表面的键合方式、形态和作用机理。认为形成单分子层包覆时表面PS-b-PAA的质量分数(C_b)为0.92％,PS-b-PAA羧基与碳酸钙表面的作用方式为:CaCO_3+[-C-CCOO^--]_n→Ca[-OOCC-C-]_n+CO3_(2-) 。在PS-b-PAA浓度较低时,热力学上的不稳定使得链呈现PAA朝下的竖直状态,而随着PS-b-PAA浓度的增加,PS链段岛状聚集体的形成,原先直立和新键合的PS-b-PAA链将逐渐地以包绕的方式结合在碳酸钙的表面。

In this paper, particulate calcium carbonate is surface treated by PS (polystyrene)-b-PAA ( polyacrylic acid) with varied amount. By measuring the dissolve curve, coating efficiency, NIR and XPS spectra, the way PS-b-PAA molecules align around and react on the surface of calcium carbonate are deduced. We suppose that surface PS-b-PAA reaches 0.92% at the stage of monolayer coverage and that surface carboxyl reacts with PS-b-PAA according to the equation CaCO3 + [-C-CCOO--](n) --> Ca[-OOCC-C-](n) + CO32-. Initially, PS-b-PAA chains bond vertically to the calcite surface with PAA block down when PS-b-PAA concentration in the solution is low. With the increase of PS-b-PAA concentration, PS block forms islandlike micelles and gradually the formerly bonded together with the newly bonded PS-b-PAA will change their shape and wrap around the particle surface.