| Polyurethanes (PU) are becoming more and more important as engineering materials, and also, important material in paint & coating industry due to their many excellent properties such as high abrasion resistance, chemical resistance and high flexibility. However, it's well known that conventional polyurethanes exhibit poor thermal stability, which limits their more application in paint & coating fields .An effective way to improve the thermal and mechanical properties of polyurethane is a chemical modification by introducing heteroaromatic groups into polyurethane backbones. In this work, polyurethanes have been modified in view of hard and soft segment respectively. A novel fluoro-containing diamine has been synthesized and was used as the chain-extender to prepare polyurethane(urea) elastomers. In addition, polyurethane was modified by incorporating polydimethylsiloxane into its soft segments in the last sector. The main contents were listed below:1. Polyurethane-urea material based on fluorine-containing bisphenoxydiamineA novel fluorine-containing bisphenoxydiamine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexa- fluoropropane (BAFP), was synthesized and characterized by means of FTIR, nuclear magnetic resonance (NMR) and EA. The obtained BAFP was used as chain-extender to prepare polyurethane-urea material (FPUU), whose morphology and properties was measured through FTIR, DSC, TGA and tensile measurements. The results showed that FPUU exhibited good mechanical properties and thermal stability than conventional polyurethane-urea (MPUU) based on MOCA. On the other hand, it could be concluded that the miscibility between soft and hard segments of FPUU was higher than that of MPUU perhaps because the introduction of fluorine atoms increased the interaction of two segments.2. Silicone-modified polyurethane-urea material A series of silicone-modified polyurethaneurea material (SPUU) were prepared with different composition ofα,ω-(6-hydroxyethoxypropyl) polydimethylsiloxane (PDMS)/polytetramethylene glycol (PTMG) mixed macrodiol. The results of field emission scanning electronic microscope (FESEM) and energy emission X-ray (EDX) measurements showed that no more than 10% (PDMS/PTMG, wt%) of PDMS could be introduced into PUU backbones. If more than 10%, the extra PDMS would separate out from PUU bulk and become solid matter.SPUU material were characterized by means of FTIR, TGA, DSC, tensile measurements and water contact angle. The results indicated that thermal stability of PUU material has been improved by incorporating a small quantity of silicone into the main chains. However, the typical composition temperatures of SPUU were not as high as that of modified PUUs in previous studies. It maybe indicated that the effect of improving the thermal stability by modifying polyurethane soft segments was not as much as that by modifying hard segments. Furthermore, the mechanical property of SPUU material has been weakened due to the introduction of silicone but the decreasing degree was very little.The results of EDX and water contact angle measurements showed that silicone segments tend to appear in the surface of SPUU films. However, compared to silicone-modified polyurethanes by introducing silicone into the side chains, the enrichment degree of silicone was not so high. It's probably because the main chains limited the activity of silicone segments.
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