Centro de Física de Materiales (CSIC, UPV/EHU)-Materials Physics Center, Paseo Manuel de Lardizabal 5, 20018 San Sebastián, Spain.
Macromol Rapid Commun. 2011 Apr 4;32(7):573-8. doi: 10.1002/marc.201000720. Epub 2011 Jan 27.
Direct observation of the miscibility improving effect of ultra-small polymeric nanoparticles (radius ≈4 nm) in model systems of soft nanocomposites is reported. We have found thermodynamically arrested phase separation in classical poly(styrene) (PS)/poly(vinyl methyl ether) blends when PS linear chains were totally replaced by ultra-small, single chain PS nanoparticles, as determined by thermo-optical microscopy measurements. Partial arrested phase splitting on heating was observed when only some of the PS chains were replaced by unimolecular PS nanoparticles, leading to a significant increase of the lower critical solution temperature (LCST) of the system (up to 40 °C at 15 vol.-% nanoparticle content). Atomic force microscopy and rheological experiments supported these findings. Thermodynamic arrest of the phase separation process induced by replacement of linear polymer chains by unimolecular polymer nanoparticles could have significant implications for industrial applications requiring soft nanocomposite materials with excellent nanoparticle dispersion in a broad temperature range.
本文报道了在软纳米复合材料的模型体系中，通过直接观察超小聚合物纳米粒子（半径≈4nm）对提高混溶性的影响。我们发现，当 PS 线性链完全被超小的单链 PS 纳米粒子取代时，在经典的聚苯乙烯（PS）/聚（乙烯基甲基醚）共混物中会发生热力学上被阻止的相分离，这是通过热光学显微镜测量确定的。当只有部分 PS 链被单分子 PS 纳米粒子取代时，观察到部分被阻止的相分离，导致体系的低临界溶液温度（LCST）显著升高（在 15vol.-%纳米粒子含量下高达 40°C）。原子力显微镜和流变学实验支持了这些发现。通过用单分子聚合物纳米粒子取代线性聚合物链来阻止相分离过程的热力学，可以为需要在较宽温度范围内具有优异纳米粒子分散性的软纳米复合材料的工业应用带来重要意义。
