| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 95 === The gold nanoparticles (GNPs) coated by MUD were successfully prepared in the organic solvent. This GNPs substituted the chain extender of polyurethanes (PU) and reacted with the diisocyanate. GNPs became a part of the polymer main chain, and hence can be dispersed uniformly in the nanocomposites. Because the previous literatures which used blend method to prepare the polymer-nanogold composites were the low content of GNPs, in this study the chemical bonding between the polymers and GNPs were formed to prepare the composites of high content of GNPs. The polyurethane-nanogold (PU-Au) nanocomposites were synthesized by the polyester and polyether individually. The preparation and characterization of nanocomposites and the effects of GNPs on the crystallinity and hydrogen-bonded in the different soft segments were investigated.
SEM, UV-Vis, FT-IR, NMR and XRD results show that PU and PU-Au nanocomposites are prepared successfully, and GNPs of uniform size are well dispersed in the solid composites. FT-IR results indicate that GNPs can improve the hydrogen-bonded between the soft and hard segments in the polyester-type PU-Au composites, but it reduces the hydrogen-bonded between the hard and hard segments in the polyether-type PU-Au composites. TGA results show that GNPs can improve the thermal stability of PU. DSC and POM results indicate that the crystallinity, number of spherulities and glass transition temperature (Tg) are increased with the amount of GNPs in the polyester-type PU-Au composites. DMA results show that the storage modulus is decreased with the amount of GNPs in the polyester-type PU-Au composites below Tg which is due to the increasing free volume, but the results of storage modulus are reverse when the temperature above Tg due to the resistance of hydrogen-bonded between GNPs and soft segments. The results of storage modulus in the polyether-type PU-Au composites are similar to the polyester-type PU-Au composites. The degree of storage modulus changes slightly in the polyether-type PU-Au composites, because the effects of hydrogen-bonded and free volume are smaller than the polyester-type PU-Au composites. Stress-strain measurement results show that the tensile strength is raised by increasing the content of GNPs in the polyester-type PU-Au composites.
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