摘要
通过表面引发单电子转移活性自由基聚合和自由基聚合法,分别将N-异丙基丙烯酰胺(NIPAM)和丙烯酸(AA)接枝聚合到纤维素纳米晶(CNCs)的羟基上,制备了PNIPAM和PAA双重接枝的改性CNCs(PNIPAM-g-CNCs-gPAA)。利用红外光谱(FT-IR)、热重分析(TGA)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外-可见光分光光度计(UV-Vis)和粒度仪等对改性CNCs进行了测试表征。FT-IR和XPS分析证实了改性CNCs的成功制备;TEM显示改性CNCs依旧保留棒状晶体形态但直径变宽;TGA表明改性CNCs的热稳定性较CNCs有显著提升;UV-Vis分析改性CNCs的低临界相转变温度(LCST)约为37℃,此时该纳米颗粒发生体积收缩,粒径收缩为原来的68%,且随着温度的提高,完成体积相转变的时间越短,此外该温度响应具有可逆性;UV-Vis对pH响应测试可知,在pH<5时,悬浮液的光透过率显著下降,表明接枝后的CNCs在强酸性条件下易团聚,而在中碱性环境下,亲水性良好,该p H响应具有可逆性。温度和pH双重响应的改性CNCs以期应用于如智能药物缓释、智能响应开关膜等领域。
In this work,N-isopropylacrylamide(NIPAM)and acrylic acid(AA)were graft-polymerized onto hydroxyl groups of cellulose nanocrystals(CNCs)by surface-initiated single-electron transfer living radical polymerization and free radical polymerization,respectively.Modified CNCs double-grafted with PNIPAM and PAA(PNIPAM-g-CNCs-g-PAA)were obtained.The modified CNCs were characterized by FT-IR,TGA,TEM,XPS,UV-Vis and particle size analyzer.FT-IR and XPS tests confirm the successful preparation of modified CNCs;TEM shows that the modified CNCs still retain the rod-like crystal shape,but the diameter becomes wider;TGA shows that the thermal stability of modified CNCs is significantly improved compared with that of CNCs;lower critical solution temperature(LCST)of modified CNCs tested by UV-Vis is about 37℃,at this time,the volume of the nanoparticles is shrinking,and the particle size(particle size meter test)is shrinking to 68%of the original,with the increase of temperature,the time to complete the volume phase transition becomes shorter,and the temperature response is reversible;pH-response test by UV-vis shows that when pH<5,the light transmittance of the suspension decreases significantly,indicating that CNCs after grafting are easy to agglomerate under strong acid condition,while in moderate alkaline environment,the hydrophilicity is well,and the pH response is reversible.The modified CNCs with dual response of temperature and pH are expected to be applied in such fields as intelligent drug sustained-release and intelligent responsive switching membrane.
作者
付志威
周益名
黄倩
朱敬洋
Zhiwei Fu;Yiming Zhou;Qian Huang;Jingyang Zhu(College of Textile Science and Engineering(International Institute of Silk),Zhejiang Sci-Tech University,Hangzhou 310018,China)
出处
《高分子材料科学与工程》
EI
CAS
CSCD
北大核心
2023年第2期143-153,共11页
Polymer Materials Science & Engineering
基金
国家自然科学基金青年基金资助项目(21908202)
中国博士后科学基金(2020M671794)。
