Thermal and osmotic deswelling of poly(NIPAM) microgel particles
Thermal and osmotic deswelling of poly(NIPAM) microgel particles
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DOI：
10.1039/ft9969203385
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发表时间：
1996-09-21
期刊：
影响因子：
--
通讯作者：
Vincent, B
中科院分区：
文献类型：
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作者：
Saunders, BR;Vincent, B
研究了温度和自由基聚合物对N，N ′-亚甲基双丙烯酰胺交联聚NIPAM（NIPAM = N-异丙基丙烯酰胺）微凝胶粒子溶胀的影响。通过光相关光谱（PCS）、透射电镜（TEM）和扫描电镜（SEM）对微凝胶颗粒进行了表征。通过TEM测定的粒径总是大于在50 ℃下通过PCS测量的粒径。SEM数据表明干燥颗粒具有扁球体形状。检测了聚（NIPAM）颗粒响应于28 - 60 ℃温度循环而塌陷和溶胀的速率，并观察到一些滞后现象。排除的游离聚合物[PEG，其中PEG =聚（乙二醇）]由于渗透压效应也导致聚（NIPAM）颗粒在25 ℃下的去溶胀。当单分散PEG的分子量大于或等于1470 g mol（-1）时，发生渗透消溶胀。较高分子量的PEG聚合物引起去溶胀程度的普遍降低（在固定浓度的PEG下）。
The effects of temperature and added free polymer on the swelling of poly(NIPAM) (NIPAM = N-isopropylacrylamide) microgel particles cross-linked with N,N'-methylene bisacrylamide have been investigated. The microgel particles were characterized by photocorrelation spectroscopy (PCS), TEM and SEM measurements. Particle sizes determined by TEM were invariably larger than those measured at 50 degrees C by PCS. SEM data suggest that dried particles have an oblate spheroid shape. The rate at which poly(NIPAM) particles collapse and swell in response to cycling of the temperature between 28 and 60 degrees C was examined and some hysteresis was observed. Excluded free polymer [PEG, where PEG = poly(ethyleneglycol)] also caused deswelling of the poly(NIPAM) particles at 25 degrees C due to osmotic pressure effects. Osmotic deswelling occurred in the presence of monodisperse PEG when the molecular weight of the latter was greater than or equal to 1470 g mol(-1). Higher molecular weight PEG polymers caused a general decrease in the extent of deswelling (at a fixed concentration of PEG).