【作者】 张军瑞；

【导师】 涂伟萍；

【作者基本信息】 华南理工大学 ， 化学工程， 2013， 博士

【摘要】 聚氨酯(PU)独特的链结构和聚集态结构赋予其极优异的物理性能和加工性能，如强度高、韧性好、优异的耐磨、耐油特性等，已被广泛地应用于工农业和日常生活的各个领域。透明聚氨酯材料既具有聚氨酯优异的性能，又具有较高的透明度，是近年来透明高分子材料的重要发展方向。根据高聚物结构理论，结晶共聚物由于存在晶区和非晶区，光线对这两相的折射率不同，因此结晶聚合物往往是不透明的，只有无规非晶的聚合物才有可能是透明的。聚酯聚氨酯中由于酯基极性高，易产生结晶，影响其透明性，而聚醚分子链间的相互作用力较聚酯弱，易无规随机排列，结晶度低，因此透明性好，目前透明聚氨酯多采用聚醚多元醇制备。但聚醚型透明聚氨酯由于分子间作用力小、内聚强度低，其机械强度较差、耐紫外和耐溶剂性能不理想。本文在前人的研究基础上，根据聚合物结构-性能之间的关系，通过合理设计聚酯多元醇的结构及选择原料，制备出高透明且性能优异的聚氨酯涂层，并对其结构-性能关系进行了深入研究，同时在此基础上对其进行改性，赋予其特殊性能，以使其适用于对涂层有特殊要求的领域，具体研究工作及取得的成果如下：（1）根据聚合物结构与性能的关系，设计合成一系列直链和支链、分子量大小和分布可控、透明、流动性好的聚酯多元醇，研究了聚酯多元醇的结构和组成对其玻璃化温度（Tg）和粘度的影响。结果表明环状单体可以提高聚酯多元醇的Tg和粘度；长链线性脂肪族二元酸和二元醇可使其Tg和粘度降低、流动性变好；少量三官能度单体的加入可以提高其Tg和粘度。（2）以聚酯多元醇和多异氰酸酯为主要原料制备一系列透明聚氨酯涂层，对其物理化学性质、机械性能和光学性能等进行测试，并对涂层结构进行了表征。研究表明：聚酯多元醇中直链单体赋予涂层优异的耐冲击性和柔韧性，环状单体使涂层硬度和剪切强度增加，涂层的冲击强度随环状单体的增加先增加后降低；环状异氰酸酯制备的涂层又韧又硬，而直链异氰酸酯赋予涂层较好的柔韧性；通过合理设计涂层的结构，使涂层的微相分离控制在一定程度，可制备出同时具有优异机械性能和光学性能的聚氨酯涂层。（3）以聚酯多元醇和含氟异氰酸酯预聚物为原料制备一系列含氟聚氨酯涂层，探讨了不同氟碳链序列长度对涂层性能的影响。结果表明：含氟链段的引入使聚氨酯内部短程有序结构程度增加，导致聚氨酯的透明度下降，而有序结构增加的程度和氟碳链的长度成反比；氟元素的引入使聚氨酯的机械性能下降，适度的微相分离可以使机械性能下降的程度降低；氟元素的引入可以提高聚氨酯的耐热性能，且异氰酸酯中氟碳链越短，聚氨酯的耐热性能越好；聚氨酯内部的氟元素有向表面迁移的趋势，使其表面能得到降低，迁移的程度和聚氨酯中的结晶程度有关。（4）通过溶胶-凝胶法制备一系列不同粒径的二氧化硅溶胶，采用原位聚合的方法将二氧化硅引入到聚酯多元醇中，将杂化聚酯与多异氰酸酯交联固化制备聚氨酯纳米复合涂层，对其结构与性能进行表征。结果表明：杂化聚酯的粘度随着二氧化硅粒径的增大而增大；二氧化硅的加入使聚氨酯的机械性能、耐磨性能和Tg得到明显的提高，且当二氧化硅表面羟基含量越高，效果越明显。涂层的透明度随着二氧化硅粒径的增大而降低，但二氧化硅的加入并没有提高涂层对紫外线的屏蔽作用。（5）以蛇纤纹石为原料，采用化学分散、酸浸方法制备出氧化硅纳米纤维。采用共混法将其引入到聚氨酯中，并对其性能进行测试。结果表明：涂层的透光率随着氧化硅纳米纤维加入量的增加而降低，涂层由无色透明转为黑色，但氧化硅纳米纤维在一定程度上提高了涂层对紫外线的屏蔽效果。同时氧化硅纳米纤维可作为补强填料进一步提高聚氨酯涂层的硬度、剪切强度、耐磨性能和热稳定性，但会使涂层的韧性降低。更多还原

【Abstract】 The unique chain and aggregation structure enables polyurethanes (PU) with excellentphysical and processing properties, such as high strength, flexibility, excellent wear andchemical resistance, and they have been applied widely in industry, agriculture and daily life.Transparent polyurethanes not only have excellent properties of PU, but also have hightransparency, they are an important research direction in recent years.According to the theory of polymer, crystalline polymers are always opaque because ofthe different refractive index between the crystalline and amorphous region, and thetransparent materials are always amorphous polymers. Polyester polyurethanes possess highpolarity structure in the form of–(C=O)-, causing polyurethanes synthesized from thesematerials to crystallize easily. Polyether macrodiols are the most commonly used materials inpreparing transparent PU as weak force between molecular chains in these materials reducescrystallinity in the PU so synthesized. However, there are some disadvantages for polyetherpolyurethanes, such as: lower mechanical strength, ultraviolet and solvent resistance are poor.On the basis of previous research, we synthesized transparent and high performancepolyurethane coatings with polyester polyols and isocyanate trimers according to therelationship between structure and properties of polymers, and we researched the relationshipbetween structure and property in PU. At the same time, polyurethanes were modified to havespecial properties and make them suitable for coating with special requirements. The specificresearch and achievements are as follows:(1) We synthesized a series of linear and branched transparent polyester polyols withcontrollable molecular weight and distribution. The structure of monomer had a significanteffect on the glass temperature (Tg) and viscosity of polyester polyols. The cyclic monomerincreased Tg and viscosity of polyester polyols, while the long linear monomer decreased theTg and viscosity, small amounts of three functional monomer also increased the Tg andviscosity of polyester polyols.(2) Transparent polyurethane coatings were synthesised with homemade polyesterpolyols and aliphatic isocyanates. The physicochemical, mechanical, optical properties andthe structure in PU were characterized. Results indicated that the linear monomers inpolyester polyols enabled PU with excellent impact resistance and flexibility, the cyclicmonomers could increase the hardness and shear strength of PU, and the impact resistanceincreased first and then declined with the increased amount of cyclic monomers. The cyclic structure in polyisocyanate endowed PU with toughness and hardness, the linearpolyisocyanate enabled PU with good flexibility. The results indicated that high transparentpolyurethane coatings with excellent mechanical properties could be synthesized bycontrolling the microphase separation in PU to a certain degree.(3) Transparent fluorinated polyurethane coatings were synthesized with fluorinatedisocyanates and polyester polyol. The length of fluorocarbon chain on the properties of PUwas discussed. Results indicated that the introduction of fluorocarbon chain increased theinternal short-range ordered structure in PU, resulting in a decline in transparency, and thedegree of the structure increased is inversely proportional to the length of fluorocarbon chain.The mechanical properties were declined as the fluorocarbon chains were introduced topolyurethanes, and the moderate micro-phase separation in fluorinated polyurethanes loweredthe degree of mechanical performance degradation. The introduction of fluorine improved thethermal resistance of polyurethanes, and the short the fluorocarbon chain, the better theperformance of heat-resistant properties. Fluorine would migrate to the surface of PU andreduced the surface energy, and the degree of migration was related to the degree ofcrystallization in PU.(4) A series of nano silica sols with different particle size were prepared by sol-gelmethod, and introduced them to polyester polyol by in situ polymerization. Transparentorganic-inorganic hybrid polyurethane coatings were prepared by nano hybrid polyester resinsand polyisocyanates. Results indicated that the viscosity of hybrid polyester resins wasimproved with increasing silica particle size. The mechanical properties, abrasion resistanceand Tg were obviously increased as nanosilica particles were introduced to PU, especiallywhen the diameter was35nm. However, the effect on UV shielding was not obvious.(5) One-dimensional nanostructure material, silica nanofibers were prepared by chemicaldispersing and acid leaching route using chrysotile as raw material, and introduced them toPU by blending method. Results showed that: the transmittance of PU decreased withincreased amount of silica nanowires, and the appearance changed from colorless to black.However, silica nanofibers improved the UV shielding to a certain extent. At the same time,silica nanofibers could be used as reinforcing filler to improve the hardness, shear strength,wear resistance and thermal stability of PU, but they would decrease the flexibility of PU.更多还原