Topology effects on the LCST of end-capped poly(ethylene glycol)s
Topology effects on the LCST of end-capped poly(ethylene glycol)s
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DOI：
10.12989/bme.2015.2.1.015
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发表时间：
2015-03-01
影响因子：
0.8
通讯作者：
Jeong, Byeongmoon
中科院分区：
文献类型：
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作者：
Kim, Jin Young;Moon, Hyo Jung;Jeong, Byeongmoon
制备了阿坝（FP-PEG-FP）和AB（mPEG-FP）类型的用五氟苯基封端的聚（乙二醇）。即使它们在组成上相似，FP-PEG-FP的低临界溶解温度（LCST）在23 ℃下观察到，而mPEG-FP的低临界溶解温度（LCST）在65 ℃下观察到。为了理解两种聚合物的溶液行为的巨大差异，使用了UV-VIS光谱、微量热法、1H-NMR光谱和动态光散射。FP-PEG-FP在亲水性PEG（1000道尔顿）的末端具有两个疏水性五氟苯基基团，而mPEG-PF具有锚定到疏水性五氟苯基基团的高度动态PEG（550道尔顿）嵌段。PF-PEG-PF不仅具有比mPEG-PF更小的构象自由度，而且可以形成广泛的分子间聚集体，因此PF-PEG-PF的LCST显著低于mPEG-PF。
Poly(ethylene glycol) end-capped with pentafluorophenyl group(s) in ABA (FP-PEG-FP) and AB (mPEG-FP) types were prepared. Even though they were similar in composition, the lower critical solution temperature (LCST) of FP-PEG-FP was observed at 23 degrees C, whereas that of mPEG-FP was observed at 65 degrees C. To understand the large difference in solution behaviour of the two polymers, UV-VIS spectroscopy, microcalorimetry, 1H-NMR spectroscopy, and dynamic light scattering were used. FP-PEG-FP has two hydrophobic pentafluorophenyl groups at the ends of hydrophilic PEG (1000 Daltons), whereas mPEG-PF has a highly dynamic PEG (550 Daltons) block that are anchored to a hydrophobic pentafluorophenyl group. PF-PEG-PF not only has a smaller conformational degree of freedom than mPEG-PF but also can form extensive intermolecular aggregates, therefore, PF-PEG-PF exhibits a significantly lower LCST than mPEG-PF. This paper suggests that topological control is very important in designing a temperature-sensitive polymer.