Coutinho Cecil A, Gupta Vinay K
Department of Chemical Engineering, University of South Florida, ENB 118, 4202 E Fowler Avenue, Tampa, FL 33620, USA.
J Colloid Interface Sci. 2007 Nov 1;315(1):116-22. doi: 10.1016/j.jcis.2007.06.016. Epub 2007 Jun 16.
Organic-inorganic composites were prepared with titanium dioxide (TiO2) nanoparticles embedded within colloidal particles of a cross-linked, thermally responsive polymer. To promote the incorporation of unaggregated nanoparticles of TiO2, temperature responsive microspherical gels (microgels) of N-isopropylacrylamide (NIPAM) with interpenetrating (IP) linear chains of poly(acrylic acid) (PAAc) were synthesized. Dynamic light scattering (DLS) measurements revealed that these microgels reversibly shrink and swell in diameter from 300-400 nm to 600-800 nm with temperature. Two types of nanoparticles of TiO2 were immobilized within the IP-microgels-fine TiO2 nanoparticles synthesized by the hydrolysis of titanium(IV) isopropoxide and commercially available Degussa P25. Characterization of the composite was conducted using transmission electron microscopy (TEM) and UV-vis absorption spectroscopy from which it was determined that the extent of loading of the TiO2 within the colloidal particles can be easily manipulated from a low value of 10% (weight) to a value as high as 75%. The TiO2 nanoparticles were in a dispersed state within the microgels and the composites showed rapid (approximately minutes) sedimentation, which is useful for gravity separations. By using turbidometry to characterize the settling behavior of the organic-inorganic composites, it was found that the settling time decreases as the content of TiO2 increases within the particles.
通过将二氧化钛（TiO₂）纳米颗粒嵌入交联的热响应聚合物的胶体颗粒中制备有机-无机复合材料。为促进未聚集的TiO₂纳米颗粒的掺入，合成了具有互穿（IP）聚丙烯酸（PAAc）线性链的N-异丙基丙烯酰胺（NIPAM）温度响应微球凝胶（微凝胶）。动态光散射（DLS）测量表明，这些微凝胶的直径随温度可逆地收缩和膨胀，从300 - 400 nm变化到600 - 800 nm。两种类型的TiO₂纳米颗粒被固定在IP微凝胶中——通过异丙醇钛水解合成的细TiO₂纳米颗粒和市售的德固赛P25。使用透射电子显微镜（TEM）和紫外-可见吸收光谱对复合材料进行表征，由此确定TiO₂在胶体颗粒中的负载量可以很容易地从低至10%（重量）的值调节到高达75%的值。TiO₂纳米颗粒在微凝胶中处于分散状态，并且复合材料显示出快速（约几分钟）沉降，这对于重力分离很有用。通过使用比浊法表征有机-无机复合材料的沉降行为，发现随着颗粒中TiO₂含量的增加，沉降时间缩短。
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