多官能化POSS及其生物可降解纳米杂化材料的制备与研究

发布时间：2018-07-07 07:00

本文选题：多面体低聚倍半硅氧烷(POSS) + 有机-无机杂化　；参考：《电子科技大学》2012年硕士论文

【摘要】：笼型多面体低聚倍半硅氧烷(Polyhedral Oligomeric Silsesquioxanes,POSS)是一种分子水平的有机-无机杂化材料,由于其独特的分子结构,基于POSS制备的有机-无机杂化材料成为当今材料学领域的研究热点。本论文在POSS以及POSS基生物医用材料的研究现状的基础上,围绕多官能化POSS单体的合成及制备工艺改进,含有POSS结构的星型杂化生物可降解聚合物的合成和表征,以及杂化球状分子增韧剂对聚乳酸材料的改性等方面展开,通过1H-NMR、GPC、FTIR、 DSC、TG、SEM和拉伸试验等手段对杂化聚合物和复合材料的结构和性能等进行了研究。首先,本文合成和表征了八聚四甲基铵倍半硅氧烷、八聚(二甲基硅氧基)倍半硅氧烷、八聚[2-(2-羟基乙氧基)二甲基硅氧基]倍半硅氧烷(POSS-OH)等三种具有不同官能团的POSS单体,获得了高纯度产物。在合成过程中,溶剂极性、反应温度、催化剂、产物处理等对POSS的单体的产率和纯度都有较大影响。其次,本文通过“先核后臂”方法,以纳米尺寸的含八羟基的POSS-OH为核,引发D,L-丙交酯开环聚合,合成了八臂星型有机-无机POSS-PDLLA杂化聚合物。GPC、DSC、TG结果显示,该杂化聚合物分子量分布极窄,热稳定性良好,表现出与普通线性聚乳酸完全不同的特性。第三,本文通过溶液聚合的方法,同样以含八羟基的POSS-OH为核,先后引发ε-己内酯(CL)和D,L-丙交酯(LA)发生次序开环聚合,制备了一系列具有不同组成(CL:LA=3:1;2:2;1:3),核为聚己内酯(PCL)软段、壳为聚乳酸硬段的星型有机-无机POSS-g-PCL-b-PLA杂化嵌段共聚物。1H-NMR谱图证实了POSS-OH的羟基确实引发了聚合,且PCL和PLA链段之间形成了嵌段结构。GPC和DSC研究表明,三种杂化嵌段共聚物分子量分布很窄且PCL的结晶受到抑制,是潜在的球状分子增韧剂。最后,本文通过溶液共混法,以POSS-g-PCL-b-PLA (CL:LA=2:2)为增韧剂,制备了组成不同的POSS-g-PCL-b-PLA/PDLLA复合材料。拉伸试验表明,当复合材料中增韧剂的含量低于10%时,它能有效改善基体材料的韧性；而当其含量增加到20%时,其增韧效果显著下降。这主要是因为在低含量下,增韧剂能以分子级状态分散在基体中,其PCL链段的结晶受到抑制,主要以无定形状态存在,因而其增韧效果非常显著。综上所述,将POSS引入到可生物降解高分子材料中,在分子水平上构建含有POSS结构的有机-无机杂化生物可降解材料,对发展具有新性能、新结构、新功能的纳米医药材料具有重要的理论意义和实用价值。
[Abstract]:Polyhedral Oligomeric SilsesquioxanesPOSS is a kind of organic-inorganic hybrid material at molecular level. Because of its unique molecular structure, the organic-inorganic hybrid material based on poss has become a research hotspot in the field of materials science. On the basis of the research status of poss and poss based biomedical materials, the synthesis and characterization of star hybrid biodegradable polymers containing poss structure have been improved around the synthesis and preparation of polyfunctional poss monomers. The structure and properties of hybrid polymers and composites were studied by means of 1H-NMR-GPC-FTIR, DSC-TGX SEM and tensile test. Firstly, three kinds of POSS monomers with different functional groups have been synthesized and characterized, including tetramethylammonium tetrasiloxane, octamer (dimethylsiloxy) silicoxane and octamer [2- (2-hydroxyethoxy) dimethylsiloxane] multisilane (POSS-OH). High purity products were obtained. In the process of synthesis, the polarity of solvent, reaction temperature, catalyst and product treatment have great influence on the yield and purity of POSS monomer. Secondly, by means of the method of "first nucleation after arm", using the nano-size POSS-OH containing octyl group as the nucleus, the ring-opening polymerization of DHL-lactide was initiated and the octa-star organic-inorganic POSS-PDLLA hybrid polymer, .GPC-PDLLA hybrid polymer, was synthesized. The molecular weight distribution of the hybrid polymer is very narrow and the thermal stability of the hybrid polymer is good. Thirdly, by solution polymerization, we have initiated sequential ring-opening polymerization of 蔚 -caprolactone (CL) and DL- lactide (LA) with POSS-OH containing octyl groups. A series of polycaprolactone (PCL) soft segments with different composition (CL: LA-31: 2: 2: 1: 3) have been prepared, and the core of PCL is polycaprolactone (PCL) soft segment, and the core of PCL is polycaprolactone (PCL), the core of which is polycaprolactone (PCL). The star POSS-g-PCL-b-PLA hybrid block copolymers with poly (lactic acid) hard segments in the shell. 1H-NMR spectra confirmed that the hydroxyl groups of POSS-OH really initiated the polymerization, and the block structure. GPC and DSC showed that there was a block structure between the PCL and PLA segments. The molecular weight distribution of the three hybrid block copolymers is very narrow and the crystallization of PCL is inhibited. Finally, a POSS-g-PCL-b-PLA / PDLLA composite with different composition was prepared by solution blending with POSS-g-PCL-b-PLA (CLL: LA2: 2) as toughener. The tensile test shows that when the content of toughener in the composite is lower than 10%, the toughness of the matrix material can be improved effectively, but when the content of the toughener is increased to 20%, the toughening effect of the composite decreases significantly. This is mainly due to the fact that at low content the toughening agent can disperse in the matrix in the molecular state and the crystallization of the PCL segment is inhibited mainly in the amorphous state so the toughening effect is very remarkable. In conclusion, the introduction of poss into biodegradable polymer materials and the construction of organic-inorganic hybrid biodegradable materials with poss structure at molecular level have new properties and new structures. New functional nanometer medical materials have important theoretical significance and practical value.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TB383.1;R318.08

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