Thermo-responsive behavior and microenvironments of poly(N-isopropylacrylamide) microgel particles as studied by fluorescent label method
Thermo-responsive behavior and microenvironments of poly(N-isopropylacrylamide) microgel particles as studied by fluorescent label method
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DOI：
10.1016/j.jcis.2005.09.002
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发表时间：
2006-04-01
影响因子：
9.9
通讯作者：
Iwai, K
中科院分区：
文献类型：
--
作者：
Matsumura, Y;Iwai, K
采用乳液聚合法制备了荧光单体4-N-（2-丙烯酰氧乙基）-N-二甲氨基磺酰基-7-N，N-二甲氨基磺酰基-2，1，3-苯并恶二唑（DBD-AE）标记的聚N-异丙基丙烯酰胺（PNIPAM）微凝胶。用浊度法和荧光法研究了微凝胶颗粒在水中的温敏行为和微环境。对于在1 mM的交联剂浓度下制备的微凝胶颗粒，浊度在约100 μ g/ml时开始增加。32.5度，但相对荧光强度急剧增加，波长。在最大荧光强度（λ（max））处的Th在约100 nm处显著蓝移。31.5表明DBD-AE单元周围的疏水性显著增加，随后微凝胶颗粒发生收缩。当交链体浓度从0.5增加到20 mM时，通过浊度分析测定的转变温度恒定到2 mM，在2和10 mM之间上升，在10 mM以上趋于平稳，并且约为10 mM。在油中的高交联剂浓度下，微凝胶颗粒内部的温度诱导的微环境变化也减少。从DBD-AE单元和另一荧光单体单元3-（2-丙烯基）-9-（4-N，N-二甲基氨基-苯基）菲（VDP）的荧光获得的结果表明，在20 mM的交联剂浓度下制备的微凝胶颗粒内部的不均匀性变高。(c)2005年爱思唯尔公司All rights reserved.
Poly(N-isopropylacrylamide) (PNIPAM) microgel particles labeled with a fluorescent monomer 4-N-(2-acryloyloxyethyl)-N-dimethylaminosulfonyl-7-N,N-dimethylaminosulfonyl-2,1,3-benzoxadiazole (DBD-AE) were prepared by emulsion polymerization Under various crosslinker concentrations. The thermo-responsive behavior and the microenviroment of the microgel particles were studied in water by turbidimetric and fluorescence analyses. For file microgel particles prepared Under the crossfinker concentration of 1 mM, the turbidity began to increase at ca. 32.5 degrees C, but the relative fluorescence intensity dramaically increased and the wavelength.,th at the maximum fluorescence intensity (lambda(max)) was dramatically blue-shifted both at ca. 31.5 degrees C with increasina the temperature, Suggesting the hydrophobicity around the DBD-AE unit was dramatically increased and the Subsequent shrinking of the inicrogel particles occurred. As the crossfinker concentration increased from 0.5 to 20 mM, the transition ternperature determined by turbidimetric analysis was constant upto 2 mM, rose between 2 and 10 mM. leveled off above 10 mM, and was ca. 34 degrees C at 20 mM. The temperature-induced microenvironmental change inside the microgel particles was also reduced at high crosslinker concentractions i oils. The results obtained from the fluorescence of the DBD-AE unit and another fluorescent monomer unit 3-(2-propenyl)-9-(4-N,N-dimethylamino-phenyl)phenanthrene (VDP) suggested that the heterogeneity inside the rnicrogel particles prepared under the crosslinker concentration of 20 mM became high. (c) 2005 Elsevier Inc. All rights reserved.