The Preparation Of Sylilated PCL-based Polyurethane And Its Hybrids With Shape Memory Effect

The linear shape memory polyurethane has the following drawbacks:low recovery forece, low recovery rate and unable to use repeatedly. To improve the above shortcomings, two different silylated polyurethanes and its hybrids were prepared. My work included there parts:The new titanate derivate Ti(-OMEA-KH560)4 with silane side group prepared by the modification of titanium tetraisopropoxide was used for the polymerization ofε-caprolactone to obtain poly(caprolactone) diol (Degree of polymerization= 10～60) in order to prepare sylilated PCL-based polyurethane (s-SPCLU). The results showed that:the structure of Ti(-OMEA-KH560)4 was consistent with the designed structure. There was no effective crosslinks in s-SPCLU for the gel content was low; the thermal resistance and melt temperature were raised with the increasing of PCL chain length.PCL diols were prepared by bulk polymerization ofε-caprolactone initiated by ethylene glycol. PCL diols were used to react with 4,4'-diphenylmethane diisocyanate and 3-aminopropyltriethoxysilane in sequence to make sylilated PCLU(e-SPCLU) with different end-capping ratio(50-100%). Results showed that:With the increasing of end-capping ratio, the gel content raised, the melt point, crystallinity, crystallization temperature of e-SPCLU was decreased and the tensile modulus and elongation at break also droped. e-SPCLU with higher rubbery modulus had higher recovery force. The shape recovery ratio increased with end-capping ratio and the recovery ratio of all the e-SPCLUs was above 96%. Compared with linear PCLU, e-SPCLU had better cycle recovery properties and thermal resistance.PU/SiO2 hybrids were prepared with e-SPCLU as the matrix, tetraethoxysilane(TEOS) as the precursor by the sol-gel process. The effects of TEOS content on the crosslink character, thermal, mechanical, shape memory properties and thermal resistance of hybrids were studied. The results showed that:the crosslinking increased to a higher extent with the addition of TEOS; The melt point, crystallization temperature raised as the existing of interaction of silica and polyurethane. With lower TEOS content, the silica had the strengthening and toughening effects. The shape recovery ratio remained above 97% after five cycles. PU/SiO2 hybrids had better thermal resistance than the e-SPCLU.