Journal of Applied Polymer Science   2015 年 132 卷 6 期

2015.02.01

Research on platinum catalysts with high activity and long life for hydrosilylation has attracted a great deal of interest because of the increasing price of platinum metal. In this study, we examined the effect of the molecular weight of carboxyl-ended hyperbranched polyester/platinum complexes (HTD-n-Pt's, where n = 1, 2, 3, or 4) on hydrosilylation activity and self-assembled morphology. Relevant parameters tuning the morphology of self-assemblies, such as the temperature, time, concentration, and relative humidity, were examined. All of the HTD-n-Pt's with various molecular weights had much higher hydrosilylation activities than did the conventional homogeneous Speier's catalyst, and the HTD-n-Pt could be self-assembled into ordered two-dimensional treelike structures with a fractal dimension ranging from 1.48 to 1.83; this indicated perfect fractal properties. With the increase of the HTD-n-Pt molecular weight, the size of the self-assembled treelike structures and the catalytic activity increased first and then decreased. The self-assembly mechanism was speculated and analyzed by dynamic light scattering, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy; these suggested good agreement with the diffusion-limited aggregation theory of particles.