Physicochimie des Polymères et des Milieux Dispersés, UMR CNRS 7615, ESPCI-Université Paris 6, 10 Rue Vauquelin, 75231 Paris cedex 05, France.
Langmuir. 2010 Feb 16;26(4):2279-87. doi: 10.1021/la902726f.
This study deals with the fine-tuning of the interactions between silica nanoparticles and a LCST polymer in order to build permanent rigid linear aggregates. LCST polymers become hydrophobic and collapse above a critical temperature. The collapse of the polymer chains at the surface of the silica particles generates an attractive potential that can overcome the repulsive electrostatic forces between the silica particles under certain circumstances. The combined use of the thermoresponsiveness of poly(ethylene oxide) and of the chemical condensation properties of silica enables us to build permanent rigid aggregates displaying rodlike shapes just by increasing the temperature. These aggregates have been characterized using two complementary techniques: transmission electron microscopy and small angle neutron scattering. For low curing time, it appears that small linear aggregates are obtained when the electrostatic surface potential (pH = 8.5) is high and the initial ionic strength is low (I approximately = 10(-3) M). For higher heating time these objects aggregate further leading to some branching and ultimately to 3D gels which phase separate.
本研究致力于调整二氧化硅纳米粒子与 LCST 聚合物之间的相互作用，以构建永久性刚性线性聚集体。LCST 聚合物在临界温度以上会变得疏水并发生收缩。在某些情况下，聚合物链在二氧化硅粒子表面的收缩会产生吸引力，从而克服二氧化硅粒子之间的排斥静电作用力。聚（环氧乙烷）的温度响应性和二氧化硅的化学缩合性质的联合使用使我们能够仅通过升高温度来构建具有棒状形状的永久性刚性聚集体。已经使用两种互补技术对这些聚集体进行了表征：透射电子显微镜和小角中子散射。对于低固化时间，当静电表面电势（pH = 8.5）较高且初始离子强度较低（I 约为 10（-3）M）时，似乎会得到小的线性聚集体。对于更高的加热时间，这些物体进一步聚集，导致一些分支，最终导致相分离的 3D 凝胶。
