RAFT与点击化学结合合成SiO2/PNIPAm杂化微球

利用可逆加成-断裂链转移(RAFT)聚合与点击化学相结合的方法,将大分子链末端含巯基的聚(N-异丙基丙烯酰胺)(PNIPAm-SH)接枝到SiO2纳米粒子上制备了温度响应的SiO2为核、PNIPAm为壳的核-壳结构的SiO2/PNIPAm纳米杂化微球。采用FTIR、热重分析(TGA)、透射电镜(TEM)和动态光散射(DLS)对SiO2/PNIPAm杂化微球进行了表征。结果表明,SiO2/PNIPAm杂化微球粒径约为286 nm,尺寸均一。热重分析表明,PNIPAm接枝率为87%(质量分数),PNIPAm分子链在SiO2粒子上的接枝密度为0.4分子链/nm2。杂化微球表现出明显的温度响应性,温度从25℃升至35℃时,杂化微球粒径从286 nm减小至268 nm,PNIPAm壳层的厚度从16 nm减小至7 nm。

Synthesis of SiO_2/PNIPAm Hybrid Microspheres by Combination of RAFT and Thiol-ene Click Chemistry

The temperature-responsive silica core-poly(N-isopropylacrylamide) shell (SiO2/PNIPAm) hybrid microspheres were prepared by grafting PNIPAm chains to SiO2 nanoparticles via the combination of reversible addition - fragmentation chain transfer (RAFT) and thiol-ene click chemistry. The SiO2/PNIPAm hybrid microspheres were characterized by FTIR, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and dynamic laser scattering (DLS). Nearly monodispersed SiO2/PNIPAm hybrid microspheres of 286 nm in average diameters were obtained. The grafting yield and grafting density of PNIPAm brushes on the SiO2 nanoparticles was about 87% and 0.40 chains/nm2. The temperature-responsive of SiO2/PNIPAm hybrid microspheres were investigated by DLS. The hydrodynamic diameters (Dh) of SiO2/PNIPAm hybrid microspheres decreased from about 286 nm to about 268 nm as the temperature of the aqueous medium increased from 25 to 35 oC, the PNIPAm shell thicknesses decreased from about 16 nm to about 7 nm.