中文摘要：

采用原位无皂乳液聚合法,以丙烯酸羟乙酯（HEA）对聚氨酯预聚体（PU）进行功能化,获得乙烯基PU大分子,继而通过自由基共聚制备聚氨酯-丙烯酸酯微乳液（APUA）;并将其应用于纸张表面改性。FT-IR证实了乙烯基PU与聚丙烯酸酯（PA）间的共聚反应;TGA亦说明PA的引入延缓了聚合物的分解。随着HEA用量的增加,APUA粒径由63.33nm下降至22.54nm;透射电镜图亦表明,未经HEA改性的APUA乳胶粒大小不均;经4%（质量分数）的HEA改性后,APUA呈现核壳结构,粒径分布相对均一。但随着PA含量的增加,乳液粒径增加,壳层PU胶粒中同时包裹多个PA胶粒。纸张性能测试表明,当体系m（2,2-二羟甲基丁酸）=10%,m（HEA）=4%,n（NCO）/n（OH）=1.6,m（PA）=35%时,以7%（质量分数）的APUA对纸张进行表面改性,纸张耐折度增加。扫描电镜亦表明改性后的纸纤维表面裂纹和缺陷明显减少,可有效改善其强度。

英文摘要：

A facile route to prepare polyacrlate/polyurethane microemulsion （APUA） by in-situ surfactant-free emulsion polymerization was proposed. Polyurethane prepolymers （PU） were functionalized by hydroxyethyl acrylate （HEA） to obtain PU end-capped with vinyl groups, and copolymerization among vinyl-containing PU and vinyl monomers was initiated subsequently. The products were thereby utilized for the surface modification of paper. FT-IR demonstrated the copolymerization between vinyl-containing PU and polyacrylate （PA）; TGA demonstrated the introduction of PA into the PU, which can delay the degradation of APUA films. The average particle size decreased from 63.33nm to 22.54nm with the increase of HEA content. Transmission electron mi- croscope showed that APUA particles unmodified with HEA displayed as spherical morphology with heteroge- neous particle size, while core-shell morphology and mono-modal distribution of particle size was detected for APUA particles modified with 4wt% HEA. However, the average particle size increased with increasing PA content, and several PA particles were simultaneously encased in PU colloidal particles. It can be also found that the folding strength of paper modified with 7wt~ APUA increased when m （DMBA）= 10%, m （HEA）= 4%, n （NCO）/n （OH） = 1.6 and m （PA）= 35%. Scanning transmission electron photographs further certified that the cracks and defects on the fibers were apparently reduced, resulting in the effective improvement of the strength.