Musch Judith, Schneider Stefanie, Lindner Peter, Richtering Walter
Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52074 Aachen, Germany.
J Phys Chem B. 2008 May 22;112(20):6309-14. doi: 10.1021/jp711939v. Epub 2008 Apr 30.
The thermoresponsive behavior of poly-(N-isopropylacrylamide) (PNiPAM) microgels embedded in a covalently cross-linked polyacrylamide hydrogel matrix was investigated using ultraviolet-visible (UV-vis) spectroscopy, small-angle neutron scattering (SANS), and confocal laser scanning microscopy. The hydrogel synthesis was performed at two different temperatures, below and above the volume phase transition temperature of PNiPAM, resulting in highly swollen or fully collapsed PNiPAM microgel particles during the incorporation step. UV-vis spectroscopy experiments verify that the incorporation of thermosensitive microgels leads to temperature-sensitive optical properties of the composite materials. SANS measurements at different temperatures show that the thermosensitive swelling behavior of the PNiPAM microgels is fully retained in the composite material. Volume and structure criteria of the embedded microgel particles are compared to those of the free microgels in acrylamide solution. To visualize the temperature responsive behavior of larger PNiPAM particles, confocal fluorescence microscopy images of PNiPAM beads, of 40-microm size, were taken at two different temperatures. The micrographs also demonstrate the retained temperature sensitivity of the embedded microgels.
利用紫外可见光谱、小角中子散射和共聚焦激光扫描显微镜研究了嵌入共价交联聚丙烯酰胺水凝胶基质中的聚（N-异丙基丙烯酰胺）（PNiPAM）微凝胶的热响应行为。水凝胶合成在两个不同温度下进行，低于和高于PNiPAM的体积相变温度，导致在掺入步骤中PNiPAM微凝胶颗粒高度溶胀或完全塌陷。紫外可见光谱实验证实，热敏微凝胶的掺入导致复合材料具有温度敏感的光学性质。不同温度下的小角中子散射测量表明，PNiPAM微凝胶的热敏溶胀行为在复合材料中完全保留。将嵌入微凝胶颗粒的体积和结构标准与丙烯酰胺溶液中游离微凝胶的进行比较。为了可视化较大PNiPAM颗粒的温度响应行为，在两个不同温度下拍摄了40微米大小的PNiPAM珠的共聚焦荧光显微镜图像。显微照片也证明了嵌入微凝胶保留的温度敏感性。
