【作者】 张步峰；

【导师】 王忠刚；

【作者基本信息】 大连理工大学 ， 高分子材料， 2010， 博士

【摘要】 微孔材料由于具有分子尺寸级别的开放孔道和较高的比表面积,在气体储存、分子筛、催化和光子晶体等诸多领域有着广泛的应用。最近几年来,微孔材料尤其是微孔有机聚合物材料在制备方面取得了重要进展。然而,到目前为止,除了已报道的几例微孔聚酰亚胺外,大部分的研究都集中在聚(乙烯苄基氯)、聚苯胺、梯形聚苯并二氧六环、共轭聚合物和聚硼酸酯等几类较为特殊的聚合物上。因此,将微孔的概念进一步拓展至更为普通的有机聚合物,成为微孔材料和聚合物化学家们当前亟需要做的工作。本论文旨在以一些已经工业化了的聚合物种类为基体树脂,例如氰酸酯树脂,聚芳酯和聚酰亚胺等,在分子水平上合理设计并合成出新的微孔有机聚合物。同时,在这种分子设计思想的启示下,开发出一些性能优异的工程和功能树脂。论文研究的主要内容及结论概况如下：1.设计并合成出具有四面体几何构型的氰酸酯单体四(4-氰酰基苯基)硅烷(TCNS)。研究发现,TCNS在稀溶液中进行固化时,可以得到高比表面积(>530 m2／g)和窄孔径分布(4-6 A)的超微孔固化树脂,但当它进行本体熔融聚合反应时,即使在较长的反应时间和非常高的反应温度下,固化后的树脂中也没有任何孔隙存在,这是因为交联网络中存在着残余的柔性线性中间体链段。该研究结果为将微孔的概念拓展至通用热固性树脂提供了一条重要的途径。2.刚性立体扭曲中心是制备微孔聚合物的重要构筑基元。通过酚酞及其衍生物在三乙胺催化下与溴化氰反应,合成了一系列含有扭曲中心的双官能氰酸酯树脂。DMA结果表明,在三嗪环交联网络中引入苯酞环后,能显著提高氰酸酯树脂的热性能。这些完全固化后的氰酸酯树脂的玻璃化转变温度(Tg)在298℃～362℃之间,超过了绝大部分双酚型氰酸酯树脂的Tg值。将所合成的氰酸酯与商品化的双酚A型氰酸酯在热稳定性、抗热氧化性以及吸水率等各种性能上进行了详细的比较,并从化学结构和交联密度的角度揭示了扭曲中心对材料性能的影响。3.采用工业原料对二乙酰基苯作为A2单体,四(4-羧酸苯基)硅烷作为B4单体,通过异相逐步缩聚反应合成了超支化芳香聚酯前驱体。研究表明,选择合适的聚合反应介质能有效地抑制聚合过程中凝胶的产生。调节反应单体的摩尔比,得到了两种类型的前驱体,即以端羧酸为主的超支化前驱体CTHP和以端乙酰基团为主的超支化前驱体ATHP。将CTHP和ATHP按一定比例混合后进行旋转涂膜,制备出含有等量羧酸端基和乙酰端基的前驱体薄膜,高温热固化后获得了具有优异热稳定性,良好耐溶剂能力,低折光指数和低介电常数的全芳香聚酯交联网络。低温氮气吸附实验结果表明,固化薄膜具有本质上的微孔特征,BET比表面积达到158m2／g,平均孔径为11.2A。4.采用一种新的含硅芳香二酸单体双(4-苄氧羰基苯基)双(4-羧酸苯基)硅烷(BBCS)与对苯二酚在吡啶中用对甲基苯磺酰氯作为缩合剂直接合成出主链含有四苯基硅烷结构以及侧链带苄酯基团的芳香聚酯。通过催化氢解反应顺利除去芳香聚酯侧链上的苄酯基团,最后得到了主链上与每个硅原子相连的两个苯环侧基对位都带有羧酸功能基团的全芳香聚酯PARB-C。沿主链两侧位置精确地分布着羧酸功能基团,使PARB-C为超高度交联微孔聚合物的制备提供了一种新的高性能树脂基体。5.从容易制备且结构规整的三角形三胺单体(结点)和刚性棒状的商品化二酐单体(连接桥)出发,选择工业生产聚酰亚胺的合成方法,制备了一系列具有微孔和介孔结构的聚酰亚胺交联网络。采用FTIR, TGA,氮气吸附,分子模拟和SEM等多种手段对聚合物的结构和形貌进行了研究。结果表明,通过调节交联网络中结点和连接桥的尺寸,就可以控制聚酰亚胺交联网络的比表面积、孔容和孔径等孔结构性质。6.以具有正四面体几何构型的四(4-氨基苯基)甲烷为四胺单体(TAPM),刚性棒状的均苯四甲酸酐(PMDA)或1,4,5,8-萘四甲酸酐(NTDA)为二酐单体,合成出具有类金刚石网络结构的聚酰亚胺。所制备的这些聚合物具有本质上的微孔特征,通过77K下的氮气吸附实验测得它们的最高比表面积可达到1400m2／g。储氢能力评估结果表明,这些聚酰亚胺交联网络的起始氢气吸附热在5.2-7.0kJ/mol之间,由TAPM和PMDA制备的聚酰亚胺在77K和3MPa下的储氢量可达到3.3wt%。更多还原

【Abstract】 Microporous materials possessing large specific surface areas and pores with molecular dimensions are of interest for applications in gas storage, molecular sieves, catalyst and photonic crystals et al.. Significant advances have been made most recently, particularly in the preparation of microporous pure organic polymers. Up to now, besides several limited examples of microporous polyimide networks, efforts to prepare microporous organic networks are mainly focused on several types of special polymers including poly(vinylbenzyl chloride), polyaniline, ladder-like poly(dibenzodioxane), conjugated polymer and poly(boronate). It will be strongly desirable to expand the microporosity concept to more common polymers. This dissertation is aimed to prepare novel kinds of microporous organic polymers with a rational design at the molecular level using common resins including cyanate resins, polyarylates and polyimides. Moreover, inspired by the molecular design idea of microporous polymers, several classes of high performance and functional polymers have been developed. The detail contents are listed as following:1. Tetrahedral cyanate monomer tetrakis(4-cyanatophenyl)silane (TCNS) is synthesiszed through multi-step reactions widely used in organic chemistry. It is observed that ultramicoporous structure with high surface areas (> 530m2/g) and narrow micopore size distribution (4-6 A) can be obtained by means of dilute solution polymerization method. On the contrary, no any porosity is detected for the cured product through bulk melting polymerization even under high curing temperature and long curing time, which reason is attributed to the existence of flexible intermediate segments. The finding may be an important approach to extend microporous concept (< 20 A) to general thermosetting resins in the area of polymer chemistry.2. A series of aromatic dicyanate monomers containing rigid contorted center, which is mostly used to construct microporous organic networks, have been synthesized by the reaction of phenolphthalein and its derivatives with cyanogen bromide in the presence of triethylamine. The dynamic mechanical analysis (DMA) results show that the introduction of phthalide ring (contorted center) into the polycyanurate network can effectively improve the thermal properties of the cyanate ester resin. The Tg values of the fully cured resins range from 298℃to 362℃, which are apparently higher than that of most bisphenol-based cyanate resins reported in the literatures. The thermal and thermo-oxidative properties as well as the water absorptions of the cured products are compared with those of the bisphenol-A cyanate ester (BACY), and the structure-property relationships are explained according to the chemical structures and crosslinking densities of the formed polymer networks.3. Using hydroquinone diacetate as A2 monomer and tetrakis(4-carboxyphenyl)silae as B4 monomer, the hyperbranched polyarylate precursors are successfully synthesized with high yields, during which the gelation process is efficiently suppressed by heterogeneous polycondensation method by means of the elaborate selection of reaction medium. The control of monomer ratio in the polymerization system leads to two type of precursors, i.e. mainly carboxyl-terminated hyperbranched polyarylate (CTHP) and mainly acetoxy-terminated hyperbranched polyarylate (ATHP). The precursor film, obtained by spin-coating from the mixture solution of CTHP and ATHP with equivalent amount of reactive carboxylic group and acetoxy groups, is readily thermally cured via transesterification reaction to form a crosslinked network, which exhibited excellent thermal stability, good chemical resistance, low birefringence and low dielectric constant as well as microporosity with average pore size of 11.2 A and surface area of 158 m2/g.4. Tetraphenylsilane-containing polyarylate with two pendant benzyl ester groups is synthesized successfully by direct polycondensation from a new silicon-containing aromatic diacid monomer bis[p-(benzyloxycarbonyl)phenyl]-bis(p-carbxyphenyl)siane (BBCS) with p-dihydroxybenzene in pyridine, using dimethylformamide as the activator and p-tosyl chloride as the condensing agent. Then, the benzyl ester groups are smoothly converted to carboxyl groups by catalytic hydrogenation, obtaining the polyarylate with two carboxyl groups attached on the phenylenes of tetraphenylsilane moiety. The presence of well-defined carboxyl groups and rigid tetrahedral structure of tetraphenylsilane in the polyarylate provides the feasible routes to the preparation of either hypercrosslinked covalent organic framework materials or optoelectronic materials through the reaction with chromophoric compounds.5. A series of rigid microporous and mesoporous polyimide networks is synthesized using a synthetic route that is closely related to the commercial preparations of aromatic polyimides, starting from readily available, well-defined triangular-like trisamino monomers (struts) and cheap, rigid rod-like bisanhydride monomers (linkers). Combined FTIR spectra, TGA analysis, N2 sorption analysis, atomistic simulations and SEM analysis clearly reveals that the pore structural properties such as BET surface area, pore volume and pore size in polyimide networks can be controlled by varying the size of the struts and linkers.6. Diamond-like polyimide networks are synthesized from tetrahedral monomer tetrakis(4-aminophenyl)methane (TAPM) and rigid rod-like bisanhydride monomers such as pyromellic dianhydride (PMDA) and 1,4,5,8-naphthalenetetracarboxylicdianhydride (NTDA). These polymers are substantially microporous materials and exhibit BET surface areas of up to 1400 m2/g as measured by N2 adsorption at 77K. The hydrogen storage capacities of these materials are also tested and a capacity of 3.3 wt% at 77K and 3 MPa was found for the best microporous polyimide prepared from TAPM and PMDA. The initial heats of adsorption of hydrogen molecules onto these polymers are around 5.2-7.0 kJ/mol.更多还原