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新型聚氨酯纳米复合材料的制备、结构与性能研究
【作者】 郭述忠；
【导师】 刘天西；
【作者基本信息】 复旦大学 ， 高分子化学与物理， 2009， 硕士
【摘要】 聚氨酯(PU)弹性体是一种介于橡胶与塑料之间的弹性材料,既具有橡胶的高弹性,又具有塑料的高强度。它的耐磨性、生物相容性与血液相容性特别突出。同时,它还具有优异的耐油、耐冲击、耐低温、耐臭氧、耐辐射和负重隔热、绝缘等性能。由于综合性能出众而被广泛应用于民用、体育、航天、军事等领域,成为不可缺少的重要材料之一。但由于其强度、生物相容性,耐热氧化等性能还不够理想,其应用受到了一定程度的限制。为了进一步拓宽其应用领域,研究者通常把某些纳米颗粒加入体系以改善聚氨醋材料的一些性能。本文在聚酯多元醇(PDA)、异佛尔酮二异氰酸酯(IPDI)、异佛尔酮二胺(IPDA)体系下,采用预聚体法制备了三种不同的聚氨酯纳米复合材料体系,并对其结构与性能进行了详细研究,所得主要研究结果如下:(1)结合了原位聚合与溶液浇铸法来制备聚氨酯/多壁碳纳米管(MWNT)复合材料。通过扫描电镜可以看出,在低含量的时候,碳管均匀分散在聚氨酯本体中,而且碳管聚合物本体与碳管之间有较强的界面相互作用力(由嵌在聚氨酯基体中被拉断的碳纳米管形貌特征),这有利于应力从聚合物本体传递到碳管,在保持高断裂伸长率的前提下成功制备了具有优异力学拉伸强度的纳米复合材料,并且这种材料的热稳定性能也有显著提高。(2)通过RAFT聚合方法合成了一系列不同分子量的PU-b-PTPM(PTPM,聚[3-(三甲氧基硅烷)丙基丙烯酸脂])两亲性嵌段共聚物,这种共聚物在THF/甲醇混合溶剂中可自组装成以PU为壳、以疏水的PTPM为核的核-壳结构,然后通过催化剂来水解和缩合成聚氨酯/聚倍半硅氧烷球纳米复合材料。由拉伸实验、TGA和原子力显微镜研究发现,相对于纯聚氨酯树脂,所得复合材料的机械性能与热稳定性能均有显著提高;且随嵌段聚合物分子量的提高,可得到数量越来越多的、尺寸均一的聚倍半硅氧烷纳米球。(3)采用十二烷基磺酸阴离子对CoAl-层状双氢氧化物(LDH)进行插层,并通过原位聚合方法首次制备出剥离型聚氨酯/CoAl-LDH纳米复合材料。使用X射线衍射、拉伸试验、热重分析法、实时傅里叶变换红外光谱等手段对纳米复合材料的结构/形态、力学性能、热稳定性进行了研究,发现其耐热氧化性能以及力学性能均显著优于纯聚氨酯树脂。
【Abstract】 The properties of polyurethane elastomer（PUE） are between rubber and plastics. PUE not only owns the property of high elasticity and high strength,but also its abradability,especially the biologic and blood compatibility.Meanwhile,PUE has other property such as oil resistivity,shockproof,low temperature resistance, resistance to ozon,radio-resistance,insulation,and so on.PUE has outstanding comprehensive properties,and has been widely used in civil,sports,aerospace, military affairs and other fields,and thus has become one kind of indispensable important materials.However,strength,biocompatibility,and thermal oxidation resistance properties of PUE greatly limit its wider applications.In order to widen its realm of applications,particular nanoparticles are usually added in PU system to improve its physical properties.In this thesis,poly（diethylene adipate）（PDA）,isophorone diisocyanate（IPDI）, isophorone diamine（IPDA） were used to prepared three different types of polyurethane nanocomposites.The main contents and the results obtained are as follows:（1） A series of polyurethane/carbon nanotube composites has been prepared through in-situ polymerization and solution casting.Homogeneous dispersion of multi-walled carbon nanotubes（MWNTs） throughout PU matrix is observed by scanning electron microscopy on the fracture surfaces of the composites.Strong interfacial adhesion between the MWNTs and the PU matrix,as evidenced by the presence of broken but strongly embedded MWNTs in the matrix,is favorable to stress transfer from polymer matrix to the nanotubes.The fine dispersion of carbon nanotubes（CNTs） and strong interfacial adhesion between the CNTs with the matrix are responsible for the simultaneous and significant enhancement in the strengthening and toughening of PU matrix.In addition,the thermal stability of PU was also improved after incorporating CNTs into the matrix.（2） A series of organic/inorganic hybrid materials have been prepared by copolymerizing polyurethane and 3-（trimethoxysilyl） propyl methacrylate（TPM） via addition fragmentation chain transfer（RAFT）,at several feeding ratios.The copolymer precursors could self-assemble into spherical micelles in selective solvents and then be hydrolyzed and condensed to generate PU-SiO2 hybrid sol-gel materials. The silica spheres undergo a change from less number with larger diameter to more number with smaller and homogeneous diameter with increasing the TPM content. The hybrid copolymers possess excellent thermal stability and mechanical property.（3） The interlayer surface of CoAl-layered double hydroxide（CoAl-LDH） was modified by exchanging the interlayer carbonate anions by dodecyl sulfate anions （DS）.PU was then intercalated by in situ polymerization to get the PU/CoAl-LDH nanocomposites.By using XRD technique,the nanoscale exfoliated dispersion of CoAl-LDH layers in the PU matrix was verified by the disappearance of the（003） reflection of the organically modified CoAl-LDH when the LDH loading is less than 2.0 wt%.The strong interaction between the LDH nanolayers and polyurethane chains is responsible for the excellent mechanical properties of PU/LDH nanocomposites.The weak alkaline catalysis of DS to polyurethane chain,together with the degradation of LDH below 300℃,accounts for the faster degradation process shown in the TGA profiles.The real-time Fourier transform infrared reveals that these nanocomposites have a slower thermo-oxidative rate than neat PU between 160℃and 340℃,due to the barrier effect of CoAl-LDH nanolayers.The nanocomposites obtained are one kind of promising flame-retardant materials.