Tuning the thermoresponsive properties of weak polyelectrolytes:: Aqueous solutions of star-shaped and linear Poly(N,N-dimethylaminoethyl methacrylate)
Tuning the thermoresponsive properties of weak polyelectrolytes:: Aqueous solutions of star-shaped and linear Poly(N,N-dimethylaminoethyl methacrylate)
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DOI：
10.1021/ma071203b
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发表时间：
2007-11-13
期刊：
影响因子：
5.5
通讯作者：
Mueller, Axel H. E.
中科院分区：
文献类型：
--
作者：
Plamper, Felix A.;Ruppel, Markus;Mueller, Axel H. E.
研究了星形和线型聚甲基丙烯酸N，N-二甲氨基乙酯（PDMAEMA）水溶液的温敏行为。观察到的浊点随着溶液pH值的升高而强烈降低。这可以通过星星聚合物随pH降低而弱带电来解释。对于高pH，浊点随分子量增加而显著降低，即，对于几乎不带电的状态，被发现几乎是独立的臂数和臂长。这些发现可以用经典的Flory-Huggins理论来解释。通过引入有效的聚合度来捕获充电时浊点的增加。具有较短臂的聚合物在低pH下显示出比具有较长臂的聚合物略高的浊点。分子内片段密度也影响观察到的表观pK（B）值，导致较高的值与较高的臂数的恒星。
We investigated the thermoresponsive behavior of aqueous solutions of star-shaped and linear poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA). The observed cloud points strongly decrease with increasing pH of the solution. This is explained by a weak charging of the star polymers with decreasing pH. A significant decrease of the cloud points with increasing molecular weight for high pH, i.e., for the almost uncharged state, was found to be virtually independent of the arm number and arm length. These findings are explained by classical Flory-Huggins theory. The increase of cloud points upon charging is captured by introduction of an effective degree of polymerization. Polymers with shorter arms show slightly higher cloud, points at low pH than polymers with longer arms. The intramolecular segment density also influences the observed apparent pK(b) values, leading to higher values for stars with higher arm numbers.