【作者】 高晓燕；

【导师】 王子忱；

【作者基本信息】 吉林大学 ， 物理化学， 2011， 博士

【摘要】 聚氨酯作为一类性能优异的多用途高分子合成材料,广泛应用在涂料、建筑、机械、胶黏剂、合成革等行业。由于组成聚氨酯的软、硬链段化学结构的不同,其热力学不相容会引发微相分离,严重影响聚氨酯的性能,从而限制了聚氨酯产业的发展。为了拓展其应用,制备高性能的聚氨酯合成材料,需要对其进行改性。通常改性的方法有两种：(1)通过异氰酸酯与多元醇的逐步聚合反应改变其化学结构；(2)在聚氨酯中加入有机或无机填料。近年来,聚合物/无机纳米复合材料具有的潜在优越性能,引起了科学界的广泛关注。由于纳米材料的小尺寸效应、表面效应、量子尺寸效应和宏观量子隧道效应,即使在较低的添加量下,聚合物/无机纳米复合材料仍会表现出比普通聚合物更优越的性能。纳米CaCO3是一种无毒、无刺激性、无气味的白色软质填料,与其它普通填料相比,处于较低的价位。近年来,随着纳米材料和纳米技术的兴起,纳米CaCO3已经广泛应用于各种聚合物中,尤其是国内众多万吨级的纳米碳酸钙生产线的建成,更是迫切要求在包括聚氨酯在内的一系列领域中获得应用,但是,有关CaCO3在聚氨酯中应用的研究还不多。经过纳米SiO2改性的聚合物具有质轻、高强度、高韧性等优点,是科学界应用最广泛的无机填料之一。因此,制备综合性能优异的聚氨酯/纳米SiO2复合材料显得尤为重要。聚氨酯是一种易燃的高分子材料,提高阻燃性是聚氨酯行业重要的研究内容之一。纳米硼酸锌是一种高热稳定性的无毒阻燃剂,具有比重小、易分散、粒度小、无毒性、受热稳定性好等显著特点。因此,把纳米硼酸锌添加到聚氨酯基体中提高其阻燃性是可行的。基于以上原因,本论文在聚氨酯体系中,选用纳米碳酸钙(CaCO3)、纳米二氧化硅(SiO2)和纳米硼酸锌(ZB)为无机填料。纳米粒子在聚氨酯中应用的关键是纳米粒子在基体中的均匀分散以及与基体具有好的相容性。本论文(1)利用多聚磷酸为磷酸化试剂,通过酯化反应,合成了系列酯含量高的磷酸酯表面活性剂；(2)用系列表面活性剂对无机纳米粒子进行表面改性,改善了无机纳米粒子的表面性能；(3)将改性后的纳米粒子首先分散在聚氨酯的反应单体多元醇中,制备出均匀分散的分散液,随后通过原位聚合法制备出分散性良好的聚氨酯/纳米无机复合材料。在此基础上,方面研究了合成表面改性剂的最佳条件,探讨了改性后无机纳米粒子的表面性能及相互作用机理；另一方面研究了不同种类纳米粒子的加入对聚氨酯内部结构、热稳定性及力学性能的影响,着重探讨了经聚丙二醇磷酸酯改性的纳米粒子在聚氨酯中的均匀分散以及界面之间的相互作用。本论文首次用聚氨酯的反应单体多元醇与多聚磷酸通过酯化反应,制备出色泽好、单酯含量高的多元醇磷酸酯；无机纳米粉体经其表面改性后,由于修饰在表面的长链烷氧基与多元醇相同,使无机纳米粉体能够均匀地分散在多元醇中；随后通过原位聚合反应,进一步均匀分散在聚氨酯中,在根本上解决了无机纳米粉体在聚氨酯中分散不均的难题。所述多元醇可以是合成聚氨酯的各种醇类,其与多聚磷酸合成多元醇磷酸酯的工艺简单、原料易得、环保、成本低廉。所采用的无机填料来源广、易加工、改性过程成本低；工艺简单、安全无污染,适用于聚氨酯的产业化发展。本论文将油酸改性的纳米硼酸锌通过原位聚合法添加到聚氨酯中,制备出分散性能良好的聚氨酯/纳米硼酸锌复合材料。由于聚氨酯易燃,而硼酸锌是一种高热稳定性的无毒阻燃剂,因此,把两者复合起来适用于阻燃型聚氨酯的发展。本论文还将经油酸改性的纳米碳酸钙通过原位聚合法添加到水性聚氨酯中,制备出的水性聚氨酯/纳米碳酸钙复合材料综合性能良好,为无机纳米粒子在水性聚氨酯中的应用奠定了基础。更多还原

【Abstract】 Polyurethane (PU) is one of the most important and versatile class of polymer materials in industry, which has been widely used in adhesives, synthetic leather, construction, automatic applications, etc. Hence, it has received wide attention for its synthesis, morphology, chemical and mechanical properties. PU generally consists of a soft segment which is a high molecular weight macrodiol and a hard segment which is composed of diisocyanate and low molecular weight diol or diamine. Due to the difference in the chemical structure of the soft and hard segment, microphase separation takes easily arising from the thermodynamic incompatibility in PU. The domain morphology in such phase-separated structures achieved by phase separation or phase mixing has a great influence on the PU properties, which has limited its wide engineering usages. To extend the application fields of PU, researches are compelled to search for alternative PU with higher performance.In general, there are two approaches:the first is to change the molecular structure of polyurethane by modification of its basic building blocks. The second is to introduce the inorganic filler into the polyurethane matrix. Nanocomposites attract increasing interests because of their potential of providing novel performances. The tremendous interfacial area in a polymer nanocomposite helps to influence the composites properties to a great extent even at rather low filler loading. However, the homogeneous dispersion of nanoparticles is very difficult to achieve, because nanoparticles with high surface energy tend to easily agglomerate. To break up the agglomerates, studies have been carried out on the approaches of in situ polymerization of monomers in the presence of nanoparticles and other intercalation polymerization techniques.In this paper, a-chlorohydrin phosphate ester and a high molecular weight poly (propylene glycol) phosphate ester (PPG-P) were firstly obtained by polyphosphoric acid (PPA). Secondly, phosphate betaine was obtained by the reaction ofa-chlorohydrin phosphate and tertiary amine.PPG and TDI were used as main materials, nano-CaCO3, nano-SiO2, nano-ZB were used as fillers to prepare PU nanocomposites.In this paper, we prepared PU/CaCO3, PU/SiO2, PU/ZB and WPU/CaCO3 nanocomposites via in-situ polymerization.In polyurethane/CaCO3 nanocomposites experiments, it was found that PPG-P had successfully attached on the surface of nano-CaCO3 and influenced the decomposition of CaCO3. Well-dispersed and long-term stable nano-CaCO3/polyol dispersions were prepared by a mechanochemical approach with the aid of poly (propylene glycol) phosphate ester (PPG-P). Polyurethane (PU)/CaCO3 nanocomposites were prepared by further in situ polymerization with 6wt% nano-CaCO3. The microstructure and dispersion of nano-CaCO3 in the nanocomposites were investigated. It was found that well dispersion was obtained up to 6 wt% of the surface treated CaCO3 loading for PU/CaCO3 nanocomposite. The segmented structures of PU were not interfered by the presence of nano-CaCO3 in these nanocomposites as evidenced by Fourier transform infrared. Compared with the pure PU, a significant improvement in thermal stability was observed with the addtion of 6wt% of the surface treated CaCO3. The experimental results suggested that the properties of nanocomposites were correlated with the dispersion of nano-CaCO3 in PU and the interfacial interactions between nano-CaCO3 and polymer matrix.In polyurethane/SiO2 nanocomposites experiments, it was found that PPG-P had successfully grafted onto the surface of nano-SiO2 and influenced the dispersion and decomposition of nano-SiO2. Then a series of polyurethane (PU) nanocomposites with the blank SiO2 and the surface treated SiO2 have been successfully prepared via in situ polymerization. The surface modification of nano-SiO2, the microstructure and the properties of nanocomposites were investigated by FTIR, SEM, XRD and TGA. The dispersion quality of SiO2 nanoparticles in PU has greatly improved by the addition of PPG-P. The segmented structure of PU has not been affected by the presence of SiO2 in these nanocomposites. The incorporation of the surface treated SiO2 into PU doesn’t improve the first decomposition temperature, but does improve the second decomposition temperature, and in the mass rang of 3 wt% to 10 wt%, the thermal stability of polyurethane increases with increasing nano-SiO2 content due to more interaction between nano-SiO2 particles and macromolecular chainsA series of polyurethane/zinc borate nanocomposites were successfully prepared via in situ polymerization. The PPG-P and OA had successfully grafted onto the surface of ZB and the dispersion quality of ZB nanoparticles in PU has greatly improved by the addition of 1% OA. The segmented structure of PU has not been affected by the presence of ZB in these nanocomposites. Moreover, the incorporation of ZB nanoparticles modified with OA greatly improved the thermal property of PU without disrupting the intrinsic structure of PU, in the range of 1%-4%, the proper amount of OAZB incorporating into PU is 2%.A series of WPU/CaCO3 nanocomposites have been successfully prepared via in situ polymerization. OA has greatly improved the surface characteristics of nanoparticles, from hydrophilic to hydrophobic. SEM examination of the fractured surfaces of nanocomposites showed that OA-CaCO3 achieved well dispersion in WPU matrix. FTIR analysis suggested no major changes in the chemical structure of WPU in the presence of 2 wt% CaCO3. Thermal stability of WPU measured by TGA was greatly improved with the addition of OA-CaCO3. Meanwhile, the mechanical properties of the nanocomposites, examined by tensile tests, showed higher tensile strength than that of the pure WPU, especially incorporation of OA-CaCO3.This paper also investigated the modification of nano-filler by PPG-P and proposed a simple model for the dispersion of nano-filler in PU matrix with the modification of PPG-P. The long alkyl chain of PPG-P is the same as PU matrix’, thus, nanoparticles modified with it can exhibit good dispersion and compatibility with PU matrix. The process of preparing phosphate ester is simple and the cost is low, moreover, the source of inorganic filler used is wide, easily to processing and the cost is low, thus, it is useful for the development of PU industry.更多还原