Does PNIPAM block really retard the micelle-to-vesicle transition of its copolymer?
Does PNIPAM block really retard the micelle-to-vesicle transition of its copolymer?
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PNIPAM 嵌段真的能延缓其共聚物的胶束到囊泡的转变吗？
DOI：
10.1016/j.polymer.2011.06.005
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发表时间：
2011-07
期刊：
影响因子：
4.6
通讯作者：
Jiang M.
中科院分区：
文献类型：
--
作者：
Wei K.;Su L.;Chen G.;Jiang M.
众所周知，聚(N-异丙基丙烯酰胺)(PNIPAM)在其LCST处的线团到球体的转变持续了几百秒，完全可逆。然而，对于含有PNIPAM的嵌段共聚物，由于PNIPAM的构象转变而导致的胶束到囊泡的热转变需要长达数周的时间，即使在远高于LCST的温度下也是如此，而且可逆性不理想。在文献中，这种缓慢的过程被归因于PNIPAM中强烈的链间氢键，这阻碍了转变。本工作制备了不对称改性的PNIPAM(Mw 10K)，即C12-PNIPAM-CA，其一端带有疏水碳链-C12H25(C12)，另一端带有亲水性羧基-COOH(CA)，并发现其以轻缔合碳链为核心形成胶束。当温度升高到PNIPAM的LCST时，胶束向囊泡的转变在30分钟内就可以实现，而相反的过程只需要几分钟。在充分监测过渡过程的基础上，提出胶束作为构建块通过结合、融合等过程构建囊泡，其中只涉及PNIPAM的局部构象调整。因此，减少胶束核对PNIPAM链构象变化的限制是实现快速转变的关键因素之一。
The well-known coil-to-globule transition of poly(N-isopropyl acrylamide) (PNIPAM) at its LCST lasts as short as hundred of seconds with fully reversibility. However, for the PNIPAM-containing block copolymers, thermal transformation from micelles to vesicles caused by the conformation transition of PNIPAM took as long as several weeks, even at the temperatures much higher than the LCST, and without satisfactory reversibility. In the literature, this slow process has been attributed to the strong interchain hydrogen bonding in PNIPAM, which retards the transition. In this work, asymmetrically modified PNIPAM (Mw 10K), i.e. C12-PNIPAM-CA with a hydrophobic hydrocarbon chain –C12H25(C12) at one end and a hydrophilic carboxyl group –COOH (CA) at the other, was prepared and found to form micelles with a core of the lightly associated hydrocarbon chains. When temperature is increased to the LCST of PNIPAM, the transformation from micelles to vesicles can be realized within 30 min, while the reverse process only takes a few minutes. Based on full monitoring of the transition process, it is proposed that the micelles serve as building blocks in constructing the vesicles via processes of combination, fusion, and etc., in which only local conformation adjustment of PNIPAM is involved. Therefore, reducing the restriction to the conformation change of PNIPAM chains, which is imposed by the micellar core, is one of the key factors in realizing the fast transition.
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影响因子：
5.5
作者：
WU, C;ZHOU, SQ
通讯作者：
ZHOU, SQ
影响因子：
4.9
作者：
Moughton, Adam O.;O'Reilly, Rachel K.
通讯作者：
O'Reilly, Rachel K.
影响因子：
5.2
作者：
Da‐Hui Qu;Qiaochun Wang;J. Ren;H. Tian
通讯作者：
Da‐Hui Qu;Qiaochun Wang;J. Ren;H. Tian
DOI：
10.1021/jp711291x
发表时间：
2008-06
期刊：
The journal of physical chemistry. B
影响因子：
--
作者：
So Young Kim;K. Lee;S. Han;B. Jeong
通讯作者：
So Young Kim;K. Lee;S. Han;B. Jeong
影响因子：
16.6
作者：
Chiu, Hsin-Cheng;Lin, Yue-Wen;Chern, Chorng-Shyan
通讯作者：
Chern, Chorng-Shyan