【作者】 李娜；

【导师】 陈煜；

【作者基本信息】 北京理工大学 ， 材料科学与工程， 2017， 硕士

【摘要】 作为自然界中存在的唯一的碱性多糖,壳聚糖因其良好的生物相容性、多功能反应活性、阳离子聚电解质、抗菌性等性能而成为高分子领域的研究热点之一。但是,壳聚糖作为一类天然多糖,其结构复杂,构象多变,使其结构与性能之间的关系无法精确控制。近年来,为了精确的分析多糖结构与性能之间的关系,控制其分子量及其分布,合成多糖逐渐进入人们的视野。到目前为止,人们已经采用多种合成手段成功制备出了与多糖具有相似结构和性能的多糖模拟物,其中,开环易位聚合（ROMP）随着其催化剂的快速发展,特殊的反应机理和温和的反应条件,成为合成多糖的一种重要的手段。基于ROMP方法,合成了与壳聚糖具有相似结构的多糖模拟物—聚双羟基降冰片烯甲胺（PHNI）。降冰片烯叔丁氧羰基亚胺（NIB）在Hoveyda-Grubbs 2代催化剂的催化下进行ROMP反应,生成聚降冰片烯叔丁氧羰基亚胺（PNIB）。随后,PNIB经不对称双羟化,脱氨基保护反应之后生成100%脱乙酰度的壳聚糖模拟物PHNI。采用傅里叶变换红外光谱（FTIR）,核磁（¹H-NMR）等手段对产物进行结构表征,结果表明,PHNI被成功制备。不同摩尔比的单体/催化剂的ROMP产物PNIB的分子量采用凝胶渗透色谱（GPC）进行测试,结果证明NIB的ROMP反应体系为活性聚合反应。不同阶段生成的聚合物的差式扫描量热仪（DSC）,热重（TG）及X-射线衍射仪（XRD）等数据表明,不同官能团的引入,使聚合物的热稳定性能、结晶性能和溶解性能发生了很大的变化,而PHNI具有良好的热稳定性能,较低的结晶度以及良好的水溶性。根据脱乙酰度的不同,壳聚糖结构中含有不同含量的乙酰氨基基团。在NIB的ROMP反应体系中,加入带有乙酰氨基的降冰片烯乙酰亚胺（NIA）,生成嵌段聚合物聚降冰片烯叔丁氧羰基亚胺-聚降冰片烯乙酰亚胺共聚物（PNIB-PNIA）。随后,PNIB-PNIA经不对称双羟化,脱氨基保护反应之后生成不同乙酰氨基含量的壳聚糖模拟物—聚双羟基降冰片烯甲胺-聚双羟基降冰片烯乙酰亚胺（PHNI-PHNIA）。采用FTIR,¹H-NMR及¹³C-NMR等手段对合成物进行结构表征,结果表明,PHNI-PHNIA被成功制备。不同摩尔比的NIB/NIA的嵌段ROMP产物PNIB-PNIA的GPC数据表明,该嵌段ROMP为活性聚合反应。不同阶段生成的嵌段聚合物的DSC,TG及XRD等数据表明,嵌段聚合物与均聚聚合物具有相似的热稳定性和结晶性,并且同样易溶于水。更多还原

【Abstract】 As the only basic polysaccharide in nature,chitosan has been a hotspot of research in polymeric material field due to its excellent performance,such as biocompatibility,multi-function reaction activity,cationic polyelectrolyte and antibacterial activity.However,as a natural polysaccharide,the complexties of structure and conformation make it extremely difficult to control the relationship between structure and property.In order to precisely analyze the relationship between structure and property,to accurately control the the relative molecular weight and distribution,the synthetic polysaccharide has been an effective research tools.Up to now,varieties of polysaccharide mimics that with similar structures and properties to nature polysaccharide had been prepared by many methods,in which,the ring-opening metathesis polymerization（ROMP）has been an important method because of the rapid development of catalyst,special reaction mechanism and moderate reaction condition.The polysaccharide with similar structure to chitosan was prepared via ROMP.The ROMP of 5-norbornene-2-methylimine-t-butyloxycarboryl（NIB）was catalyzed by Hoveyda-Grubbs 2nd catalyst to afford poly（5-norbornene-2-methylimine-t-butyloxycarboryl）（PNIB）.Then the chitosan mimics,poly（5,6-dihydroxynorbornene-2-methylimine）（PHNI）,was synthesized after the asymmetric dihydroxylation and deprotected of amino of PNIB.The result of Fourier transform infrared spectroscopy（FTIR）and ¹H nuclear magnetic resonance（¹H-NMR）of products were showed the mimic,PHNI,was successfully prepared.The ROMP system of different molar ratio of monomer and catalyst were measured by gel permeation chromatography（GPC）,the result showed the ROMP of NIB was a“living”polymerization.The differential scanning calorimetry（DSC）,thermogravimetry（TG）and X-ray diffraction（XRD）datas of polymers in each step showed the thermal stabilities,crystallinities and solubilities were significantly changed.The PHNI has excellent thermal stability,low crystallinity and excellent solubility in water.The contents of acetamide group in chitosan were different due to the different degree of deacetylation of chitin.The 5-norbornene-2-methylimine-acetyl（NIA）was added into the ROMP system of NIB to afford block polymer PNIB-PNIA.Then the chitosan mimic with different content of acetamide group,poly（5,6-dihydroxynorbornene-2-methylimine）-poly（5,6-dihydroxynorbornene-2-methylimine-acetyl）（PHNI-PHNIA）were synthesized after the asymmetric dihydroxylation and deprotected of amino of PNIB-PNIA.The result of FTIR,¹H-NMR and ¹³C-NMR of products were showed the mimics,PHNI-PHNIA,was successfully prepared.The block-ROMP system of different ratio of NIB and NIA were measured by GPC,the result showed the block-ROMP of NIB and NIA was also a“living”polymerization.The DSC,TG and XRD datas of block polymers in each step showed the thermal stabilities,crystallinities and solubilities were significantly changed.The PHNI-PHNIA has excellent thermal stability,low crystallinity and excellent solubility in water.更多还原