Temperature-dependent properties of telechelic hydrophobically modified poly(N-isopropylacrylamides) in water:: Evidence from light scattering and fluorescence spectroscopy for the formation of stable mesoglobules at elevated temperatures
Temperature-dependent properties of telechelic hydrophobically modified poly(N-isopropylacrylamides) in water:: Evidence from light scattering and fluorescence spectroscopy for the formation of stable mesoglobules at elevated temperatures
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DOI：
10.1021/ma0600254
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发表时间：
2006-04-18
期刊：
影响因子：
5.5
通讯作者：
Winnik, FM
中科院分区：
文献类型：
--
作者：
Kujawa, P;Tanaka, F;Winnik, FM
疏水改性（HM）遥爪聚的自组装性能用荧光光谱法研究了N-异丙基丙烯酰胺（PNIPAM）在0.1 ~ 11 g L ~（-1）水溶液中的荧光行为，以及通过在包含它们的浊点（T-cp）和线圈到线圈的温度域上的静态（SLS）和动态（DLS）光散射，球转变温度（T-M）。遥爪HM-PNIPAM样品具有正十八烷基末端，并且它们的摩尔质量（M.）范围为12 000 - 49 000 g mol（-1），多分散指数低于1.20。在冷水溶液中，HM-PNIPAM样品以花状胶束的形式缔合（10.8 < R-H <17.5nm，R-G/R-H一致于1.3-1.5），其由一致于16-27个聚合物链组成，取决于它们的分子量。在高于T-M的平衡条件下加热的溶液中，具有塌陷环的单个花胶束缔合形成稳定的介观分子（R-G/R-H类似于0.80），其包含数百个链，具有比水合花胶束的疏水核心更刚性和更极性的内部。介小珠的尺寸随着聚合物浓度的增加而增加（19 < R-H < 115 nm），但在所有情况下，介小珠的尺寸分布都比冷溶液中相应聚合物胶束的尺寸分布窄。
The self-assembling properties of hydrophobically modified (HM) telechelic poly(N-isopropylacrylamides) (PNIPAM) were studied in aqueous solutions of concentration ranging from 0.1 to 11 g L-1 by fluorescence spectroscopy, using N-phenyl-1-naphthylamine as a probe, and by static (SLS) and dynamic (DLS) light scattering over a temperature domain encompassing their cloud point (T-cp) and coil-to-globule transition temperature (T-M). The telechelic HM-PNIPAM samples bear n-octadecyl termini, and their molar mass (M.) ranges from 12 000 to 49 000 g mol(-1) with a polydispersity index lower than 1.20. In cold aqueous solution, the HM-PNIPAM samples associate in the form of flower micelles (10.8 < R-H < 17.5 nm, R-G/R-H congruent to 1.3-1.5) consisting of congruent to 16-27 polymer chains, depending on their molecular weight. In solutions heated under equilibrium conditions above T-M, individual flower micelles with collapsed loops associate to form stable mesoglobules (R-G/R-H similar to 0.80) comprising a few hundreds chains with a more rigid and more polar interior than the hydrophobic core of hydrated flower micelles. The size of the mesoglobules increases with increasing polymer concentration (19 < R-H < 115 nm), but in all cases the mesoglobule size distributions are narrower than those of the corresponding polymer micelles in cold solutions.