科研之友
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摘要
The self-assembly of hyperbranched polymers (HBPs) is a powerful strategy to design and fabricate functional materials. In this paper, we present a novel hybrid self-assembly of carboxyl-ended hyperbranched polyester/platinum complex in a mixed solvent of chloroform and ethanol. Both crystalline and amorphous domains were observed in the self-assembled micrometer-sized lamellar films using transmission electron microscopy. The indications for the coordination bond (-COOPt) include the appearance of a new peak at 1605 cm(-1) and its shift to 1634 cm(-1) in infrared spectra, the disappearance of C1s peak at 288.6 eV, the emergence of a peak at 73 eV corresponding to Pt4f in X-ray photoelectron spectra. The self-assembly mechanism was further analyzed, suggesting that the coordination between carboxyl-ended group and platinum plays a key role in the micro-phase separation and the formation of ordered films. The amphiphilic intramolecular chains and end groups of carboxyl-ended hyperbranched polyester/platinum complex aggregated, respectively, and formed ordered self-assemblies with a crystal structure in the mixed solvent. TGA and XRD analyses of the self-assembled films confirmed that the crystal structure originated from the polymer chains. The platinum appeared preferentially in the surface region of the complex, demonstrating much higher catalytic activity for hydrosilylation than traditional homogeneous platinum catalyst.
