【作者】 高琼芝；

【导师】 曾幸荣；

【作者基本信息】 华南理工大学 ， 材料学， 2011， 博士

【摘要】 超支化聚合物由于具有独特的球形多分枝结构,与线性聚合物相比有许多优点:如粘度低、溶解性好、活性高、与其它材料有较好的相容性等,可被用于制备高性能的超支化聚合物基有机/无机杂化涂料。但目前关于UV固化超支化聚合物基杂化涂料的研究还较少。本论文采用软硬段比例不同的超支化聚氨酯丙烯酸酯-聚氨酯双丙烯酸酯（HBPUA-PUDA）作为有机组分,以溶胶-凝胶法制备的含乙烯基的偶联剂改性的硅溶胶为无机组分,通过UV固化制备硬度高、柔韧性好、耐磨性优良的HBPUA-PUDA/SiO₂杂化涂料。研究HBPUA-PUDA/SiO₂杂化涂料的组成、结构、性能、UV固化反应动力学及热稳定性与热降解机理。论文的研究内容和成果包括如下四点。第一:以异佛尔酮二异氰酸酯（IPDI）和丙烯酸羟乙酯（HEA）的加成物（IPDI/HEA）为改性剂,对超支化聚酯B-H20的端羟基进行改性,制备了一系列分子量不同的UV固化超支化聚氨酯丙烯酸酯（HBPUA）;采用GPC、FT-IR、1H-NMR对HBPUA结构进行了表征;探讨了预聚物分子量对粘度、固化膜机械性能及UV固化速率的影响。发现合成HBPUA的最佳反应条件为:采用0.5 wt.%二月桂酸二丁基锡为催化剂,第一步反应温度为35℃,反应时间为150min;第二步的反应温度为70℃,反应时间为180 min。HBPUA的粘度比线性的聚氨酯丙烯酸酯（PUA）低得多;随着B-H20端羟基改性程度的增加,HBPUA分子量的增加,分子量分布变宽。预聚物HBPUA的UV固化速率较快,固化时碳碳双键的最大转化率达81%。随着分子量的增加,固化膜的摆杆硬度增加,但柔韧性和附着力下降。第二:以IPDI/HEA为改性剂,对不同摩尔比的超支化聚酯（B-H20）及聚乙二醇（分子量为200和400）的端羟基改性,可制备出一系列软硬段含量不同的超支化聚氨酯丙烯酸酯-聚氨酯双丙烯酸酯（HBPUA-PUDA）预聚物;采用DSC、FTIR等方法探讨了PEG分子量及用量对反应速率、预聚物粘度、UV固化速率、固化膜性能等的影响。发现随着PEG分子量与用量的增加,反应时间逐渐增加,HBPUA-PUDA粘度也逐渐增加。与HBPUA相比,HBPUA-PUDA的固化速率较慢,固化时碳碳双键的转化率下降;其固化膜的摆杆硬度较HBPUA固化膜低,并且随着PUDA含量与分子量的增加,HBPUA-PUDA固化膜的硬度逐渐下降,但其柔韧性、附着力及冲击强度较HBPUA高,并随着PUDA含量与链长的增加,其柔韧性、附着力及冲击强度升高的幅度增大;以HBPUA-PUDA30的综合性能最佳。HBPUA-PUDA的固化膜出现两个玻璃化转变温度,且随着PUDA含量和链长的增加,软段的Tg,s逐渐降低,硬段的Tg,h逐渐升高。第三:将HBPUA-PUDA30与用偶联剂γ-甲基丙烯酰氧丙基三甲氧基硅烷（MPTMS）改性的硅溶胶按不同比例混合,制备了一系列可UV固化的HBPUA-PUDA/SiO₂杂化涂料;研究了杂化涂料的配比对杂化漆膜的结构、界面相容性及性能的影响。发现当MPTMS与正硅酸乙酯（TEOS）的摩尔比为1:3时,杂化涂料的胶凝时间高于183d;与HBPUA-PUDA相比,HBPUA-PUDA/SiO₂杂化涂料的UV固化速率较快,C=C双键的转化率增加了5%左右。HBPUA-PUDA/SiO₂杂化漆膜的有机/无机相间具有良好的相容性,纳米SiO₂粒子均匀地分散于有机相中;当SiO₂用量为30%时,HBPUA-PUDA/SiO₂杂化漆膜的Tg较杂化前提高了18.4℃,储能模量也较杂化前增加了。随着SiO₂用量的增加,HBPUA-PUDA/SiO₂杂化漆膜的摆杆硬度增加,冲击强度先增加再减少,附着力和柔韧性有所下降,其中以HBPUA-PUDA/SiO₂-30的综合性能最佳:透光率为93.1%、摆杆硬度为0.74、附着力为0级、柔韧性为2mm、冲击强度为43Kg.cm、300圈的磨耗量仅为14.8mg。第四:采用TGA-FTIR联用的方法研究了杂化漆膜的热稳定性,探讨了杂化漆膜的热降解机理。结果表明,固化漆膜的热失重分为两个阶段:在300℃～370℃间的热失重主要对应为HBPUA-PUDA中聚氨酯丙烯酸酯基团的分解,主要分解产物有CO₂、小分子胺及异氰酸酯的化合物;在390℃～460℃间的失重是由于HBPUA的超支化聚酯的核心单元及PUDA链中聚醚软段的分解,分解产物有PUDA软段分解形成的小分子醛及超支化聚酯的核分解的脂类等。纳米SiO₂粒子能有效的提高漆膜的耐热性,并且硅溶胶用量越高,漆膜的热分解温度越高;当SiO₂用量为30%时, HBPUA-PUDA/SiO₂-30杂化漆膜的第一阶段的分解温度较HBPUA-PUDA漆膜的提高了15°C左右。更多还原

【Abstract】 Due to the unique spherical-multibranched structure,hyperbranched polymer （HBP） has outstanding performance, such as low viscosity, high solubility and reactivity, good compatibility. Therefore, HBP can be applied to prepare high performance UV-curable hyperbranched polymer/inorganic hybrid coatings. However, there are few reports about HBP used as prepolymer in UV-cured hybrid coatings at present. In this work, UV-curable HBPUA-PUDA/SiO₂ hybrid coatings with high hardness, good flexibility and abrasive resistance were prepared by two parts: hyperbranched urethane acrylate-urethane diacrylates （HBPUA-PUDA） with different proportion of hard segment and soft segment was used as organic component, and vinyl-modified silica sol prepared by sol-gel method was used as inorganic component. The composition, structure, properties, photopolymerization kinetics and thermal degradation mechanism of HBPUA-PUDA/SiO₂ hybrid coatings were studied. The main research contents and achievements are listed as follow.Firstly, a series of UV-curable hyperbranched polyurethane acrylates （HBPUA） were synthesized from hyperbranched ester （B-H20）, isophorone diisocyanate （IPDI） and 2-hydroxyethyl acrylate （HEA）. The products were characterized by GPC, FTIR and 1H-NMR. The effect of molecular weight on the viscosity of prepolymer, UV-curing, mechanical properties of the cured films was studied. It was found that the optimal synthesis conditions of HBPUA was that the isocyanate adduct of IPDI/HEA was prepared with 0.5wt.% DBTDL as catalyst at 35℃for 150min, and then the adduct reacted with B-H20 at 70℃for 180min. The results showed that the viscosity of HBPUA was much lower than that of the linear PUA. The results of GPC showed that the molecular weight distribution index increased with the increase of molecular weight of HBPUA. The curing rate of HBPUA was fast and percentage conversion of C=C is 81%. With the increase of molecular weight of HBPUA, the pendulum hardness of the cured films increased, however, the flexibility and adhesion of the cured films decreased.Secondly, UV-curable hyperbranched polyurethane acrylates-polyurethane diacrylates （HBPUA-PUDA）was synthesized from the isocyanate adduct of IPDI/HEA and different proportion of B-H20 and PEG. The effect of molecular weight and content of PEG on the viscosity of prepolymer, UV curing and the mechanical properties of the cured films was studied. It was found that the reaction time of the second step and the viscosity of HBPUA-PUDA increased with the increase of content and molecular weight of PEG. The curing rate and conversion percentage of C=C of HBPUA-PUDA was lower than HBPUA’s. With the increase of content of PUDA, the flexibility, adhesion and impact strength of the cured films increased, however, the pendulum hardness of the films decreased, the comprehensive performance of HBPUA-PUDA30 was the best. The results of DSC analysis showed that there were two Tg in the cured films of HBPUA-PUDA, with the increase of the content of PUDA, the Tg,h of hard segment increased, but the Tg,s of soft segment decreased.Thirdly, A series of UV-curable HBPUA-PUDA/SiO₂ hybrid coatings were prepared from two parts: HBPUA-PUDA30 was used as organic components and the modified silica sol from TEOS and MPTMS was used as inorganic components. The effects of the ingredient on structure, interfacial compatibility, UV-curing and properties of hybrid films were studied. It was found that the gel time of HBPUA-PUDA/SiO₂ was 183d when the ratio of MPTMS toTEOS was 1/3. The curing rate of HBPUA-PUDA/SiO₂ was faster than HBPUA-PUDA and the conversion percentage of C=C was 5% higher than HBPUA-PUDA’s. HBPUA-PUDA/SiO₂ hybrid films had good interfacial compatibility and SiO₂ were uniformly distributed in organic matrix. Tg of HBPUA-PUDA/SiO₂ hybrid coatings increased by 18.4℃than HBPUA-PUDA, and the energe storage modulus also increased than HBPUA-PUDA. When the content of modified silicane sol was 30wt.%, HBPUA-PUDA/SiO₂ hybrid coatings had optimal properties with transmittance of 93.1%, pendulum hardness of 0.74, adhesion of 0 grade, flexibility of 4mm, impact strength of 43 kg.cm and abrasion resistance of only 14.8mg after 300 wear cycles.Finally, The thermal stability thermal degradation mechanism of the HBPUA-PUDA/SiO₂ films was studied by using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy （TGA/FTIR）. The results showed that all films exhibited two degradation stages located at about 320 and 440°C corresponding to the degradation for hard segments of urethane-acrylate and the degradation for soft segment and polyester core, decomposition products in the first stage were CO₂, amine with lower molecular weight, isocyanate and so on, in the second stage there were aldehyde, ester with lower molecular weight and some delayed CO₂. The results from the analysis of TGA/FTIR also indicated that decomposition temperature increased with the increase of the content of SiO₂, decomposition temperature of the HBPUA-PUDA/SiO₂-30 film were 15°C higher than that of the pure polymer.更多还原