【作者】 徐坤；

【导师】 周树学； 武利民；

【作者基本信息】 复旦大学 ， 材料物理与化学， 2009， 博士

【摘要】 有机无机纳米复合材料综合了有机材料的特性（韧性好、耐冲击、质量轻、易加工等）和无机材料的优点（高强度、高硬度、热稳定性、抗腐蚀和优异的光学性能等）,受到了科学界越来越广泛的关注,并在许多领域已得到较好的应用。紫外光纳米复合材料既有杂化材料的高性能和新功能,又有紫外固化的环保友好性,完美结合纳米复合与紫外光固化技术的优点,大大推动涂料的发展与应用。目前,文献中有关紫外光固化纳米复合涂层的研究集中在纳米SiO₂、纳米TiO₂、粘土等纳米材料体系,对纳米ZrO₂的应用研究较少。但纳米ZrO₂具有硬度高、折光指数高、化学惰性、热稳定好等优点,是制备高力学性能涂层或光功能涂层的理想纳米填料。本文以市售纳米ZrO₂粉体和非水合成纳米ZrO₂晶粒为原料,通过与不同比例的活性单体、聚氨酯丙烯酸酯（PUA）低聚物及光引发剂相复合,制备纳米复合涂料。并以此为涂料体系,采用介电树脂固化监测仪（DEA）为新的在线监测手段,考察了紫外光固化纳米复合涂料的固化动力学行为,研究了纳米ZrO₂粒子在完全初级粒子分散状态下,纳米复合涂层的力学性能、光学性能及热学性能,考察了改性ZrO₂纳米粒子在不同活性单体及低聚物中的相行为以及纳米ZrO₂粒子的涂层性能调节效率对有机基质组成的依赖性。具体研究内容及结果如下:采用市售ZrO₂粉体为原料,经γ-缩水甘油醚氧丙基三甲氧基硅烷（Z-6040）改性后,与聚氨酯丙烯酸酯低聚物（UVU6219）和二缩三丙二醇二丙烯酸酯（TPGDA）等组分共混制备了紫外光固化聚氨酯/ZrO₂纳米复合涂层。利用DEA系统研究了引发剂类型与用量、光强、膜厚、固化气氛、纳米ZrO₂用量等因素对纳米复合涂层紫外光固化动力学的影响规律,并与在线红外光谱研究结果进行了比较。研究发现,DEA获得的离子粘度对数（Logη）-时间（t）曲线与占线红外光谱获得的双键转化率（C）-时间（t）曲线在转化率低于85%时有很好的对应关系,而在高转化率阶段（＞85%）,DEA具有更高的灵敏度,对于纳米复合涂料配方和固化工艺优化具有很好的使用价值。另外,由于纳米ZrO₂粉体的复合导致涂层透明性下降,纳米复合涂层的光固化转化率随着纳米ZrO₂用量的增加而下降。采用溶剂热合成法获得的高结晶性纳米ZrO₂粒子为原料,经甲基丙烯酰氧基丙基三甲氧基硅烷（MPS）表面修饰后,与聚氨酯丙烯酸酯低聚物（6148J-75）共混,制备纳米复合涂料。考察了纳米ZrO₂晶粒改性工艺对涂层透明性以及改性纳米ZrO₂用量对涂层光固化动力学、光学性能、力学性能和热学性能的影响规律。研究表明,纳米复合涂层存在从透明向不透明转变的临界ZrO₂用量,即20wt%。在临界浓度以下,纳米复合涂层完全透明,纳米ZrO₂粒子在涂层中完全达到初级粒子分散水平,涂层的光固化转会率随着纳米ZrO₂用量的增加而增大,硬度、耐磨损和热稳定性等性能得到显著改善,折光指数最高可达1.63。但在临界ZrO₂含量以上时,涂层中的纳米粒子发生团聚,涂层透明性迅速下降,各项性能急剧恶化,甚至低于纯聚氨酯涂层的性能。在前述工作基础上,进一步深入研究了MPS改性的纳米ZrO₂晶粒在不同紫外光固化单体和低聚物中的分散稳定行为,并考察了相应纳米复合涂层的力学性能和光学性能。研究发现,MPS改性纳米ZrO₂粒子在小分子活性剂中的分散性优于PUA低聚物中的分散性,MPS接枝量越少,纳米复合涂层的透明性越好。在TPGDA中,ZrO₂添加量可以达到62wt%而保持透明。因此,涂层透明向不透明转变的临界ZrO₂用量可以通过在PUA低聚物中加入活性稀释单体加以调节。性能测试表明,有机基质的力学性能越佳,则纳米ZrO₂粒子对涂层力学性能的改进效率越高。另外,本文还初步探讨了TiO₂溶胶作为热固性丙烯酸树脂涂层固化剂的可行性,以替代传统的异氰酸酯等毒性大的有机固化剂。该TiO₂溶胶由溶胶—凝胶法制备,为网络状团簇结构。采用DEA考察了其与含羧基官能团的丙烯酸树脂的固化行为。研究初步证实了TiO₂溶胶对丙烯酸树脂的固化交联能力,并且研究表明,TiO₂的引入,有助于提高涂层的力学性能、热稳定性及紫外屏蔽性。为新型无毒固化剂与纳米杂化技术在双组分热固化涂层中应用开辟了新的思路。更多还原

【Abstract】 Organic-inorganic hybrid materials combine both the advantages of organic polymer（flexibility,light weight,good impact resistance,good processability,etc.） and inorganic materials（high mechanical strength,high hardness,good chemical resistance,thermal stability,optical properties,etc.） and have been widely applied in various fields.Especially,the UV curable hybrid coatings have been widely concerned since they possess both the advantages of UV-curing process and of hybrid nanocomposite materias,namely,environmental-friend and high performance（or new function）.Up to now,some UV curable nanocomposite coatings were reported. However,the study was still limited and mostly focused on the systems containing SiO₂,TiO₂,and clay.The application of ZrO₂ nanoparticles was rarely reported.ZrO₂ nanoparticles would be an ideal building block for nanocomposites because they offer several advantages such as chemical inertness,excellent thermal stability,high refractive index,and high hardness.In this study,commercial ZrO₂ nanopowder or non-aqueous synthesized ZrO₂ nanocrystals was incorporated into poly（urethane-acrylate） oligomer（PUA）,monomers to fabricate UV-curable nanocomposite coatings.The photopolymerization kinetics of PUA/ZrO₂ nanocomposite coatings was on-line and in-real-time monitored with microdielectrometry（DEA）.Their mechanical properties,thermal properties and optical properties of the nanocomposite coatings as well as the phase behavior of ZrO₂ nanoparticles in different monomers and PUA oligomerr was studied.The dependence of the improving efficiency of nano-ZrO₂ on the properties of organic coatings was deeply investigated.All the results are expected to provide some concrete evidence for the development and application of nanocomposites.The detailed research contents and results are detailedly described as follows:Commercial ZrO₂ nanoparticles were functionalized by 3-glycidyloxypropyltrimethoxysilane（Z-6040）,After that,the modified nano-ZrO₂ were incorporated into PUA oligomer（UVU6219） and tripropylene glycol diacrylate （TPGDA） to prepare UV-curable PUA/ZrO₂ nanocomposite coatings.Effect of the zirconia content on the UV-curing kinetics of the coatings was investigated by dielectric analysis（DEA）.The influence of photoinitiator types,photoinitiator content, UV irradiation intensity,atmospheric character and film thickness were also investigated.For comparison,real-time infrared spectroscopy（RTIR） was also employed.Linear relationship between logηand C at conversion lower than about 85%is acquired via a large numbers of comparisons between DEA and RTIR results for those PUA/ZrO₂ nanocomposite coatings.DEA monitoring has longer time to reach polymerization equilibrium than RTIR for those cases with high limited conversion,suggesting that the former is more sensitive to C=C bond conversion than RTIR at high conversion stage（C＞～85%）.Due to the good reproducibility and sensitivity,DEA will be a highly efficient tool for the optimizations of both UV-curable coatings formulation and curing condition.In addition,the final double bond conversion decreases with increasing nano-ZrO₂ content because the transparency of the coatings unavoidably reduces after ZrO₂ nanopowder is incorporated.Highly-dispersible zirconia nanocrystals,ex situ synthesized from a solvothermal reaction of zirconium-（Ⅳ） isopropoxide isopropanol complex in benzyl alcohol,were functionalized with 3-（trimethoxysilyl）propyl methacrylate（MPS） and blended with UV-curable polyurethane oligomer（6148J-75） to fabricate transparent PUA/ZrO₂ nanocomposite coatings.Their photopolymerization kinetics,mechanical properties, thermal properties and optical properties were investigated.A critical ZrO₂ concentration of 20 wt%was observed for the evolutions of both the structure and properties of the nanocomposites as a function of ZrO₂ content.Below the critial concentration,completely transparent nanocomposite film was obtained and homogeneous dispersions of ZrO₂ nanoparticles with primary particle size level were achieved.As a consequence,the nanocomposites exhibit increasing final C=C double bond conversion,refractive index,hardness,modulus,and thermal stability as ZrO₂ content increases.Particularly,the nanocomposite with 20 wt%of ZrO₂ has extremely high performance,namely,a high refractive index of 1.63,82%increment on hardness and about 60℃higher thermal decomposition temperature relative to pure PUA film.However,beyond this critical ZrO₂ loads,ZrO₂ nanoparticles tend to agglomerate in the nanocomposite,leading to serious reduction of the transparency and thus lower final conversion,nearly no improvement on properties in comparison with pure PUA coating.Based on the above study,the phase behavior of MPS-functionalized ZrO₂ was further investigated in monomers or PUA/monomer mixtures.Their mechanical properties and optical properties were investigated as well.It’s found that the existence of reactive monomers with low molecular weight facilitates the compatibility between the PUA and MPS-functionalized ZrO₂.And the higher the amount of MPS attached to ZrO₂ nanoparticle is,the lower the transparency of nanocomposite coating is.The coatings keep transparent even at ZrO₂ content of 62 wt%in pure TPGDA.Thus,the critical ZrO₂ concentration can be adjusted by the composition of organic matrix.Moreover,the better the mechanical properties of the organic matrix are,the higher the improving efficiency of ZrO₂ on mechanical properties of the coatings is.In addition,preparation of thermosetting acrylic coatings with titanium-oxo-cluster as a curing agent is primarily confirmed.The effects of the titania content,the preparation condition on the structures and properties of the hybrid materials were studied.DEA was employed to monitor the curing reaction.The results indicate that the resulted acrylic/titania coatings have better thermal stability, mechanical property and UV-block property.Anyway,this method opens another way for fabrication of thermosetting coatings,which can eliminate the toxicity of common organic curing agent and meanwhile endow the coatings with the high performance of hybrid coatings.更多还原