ZetaPlus Zeta电位测量应用案例-19

文献名： Thermal and osmotic deswel领 of poly(NIPAM) microgel particles 作者： Brian R. Saunders and Brian Vincent 摘要： The effects of temperature and added free polymer on the swel领 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 °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 cyc领 of the temperature between 28 and 60 °C was examined and some hysteresis was observed. Excluded free polymer [PEG, where PEG = poly(ethyleneglycol)] also caused deswel领 of the poly(NIPAM) particles at 25 °C due to osmotic pressure effects. Osmotic deswel领 occurred in the presence of monodisperse PEG when the molecular weight of the latter was 1470 g mol1. Higher molecular weight PEG polymers caused a general decrease in the extent of deswel领 (at a fixed concentration of PEG).