Water-Soluble Copolymers. 62. Nonradiative Energy Transfer Studies of pH- and Salt-Responsive Associations in Hydrophobically Modified, Hydrolyzed Maleic Anhydride-Ethyl Vinyl Ether Copolymers
Water-Soluble Copolymers. 62. Nonradiative Energy Transfer Studies of pH- and Salt-Responsive Associations in Hydrophobically Modified, Hydrolyzed Maleic Anhydride-Ethyl Vinyl Ether Copolymers
复制标题
水溶性共聚物。
DOI：
10.1021/ma00125a011
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发表时间：
1995
期刊：
影响因子：
5.5
通讯作者：
C. McCormick
中科院分区：
文献类型：
--
作者：
Yuxin Hu;Michael Krämer;C. Boudreaux;C. McCormick
一系列标记的，疏水改性的聚合物的基础上的交替共聚物的马来酸酐和乙基乙烯基醚（MAEVE）已被合成，以具体解决的问题，在域组织的封闭，聚皂系统和开放，缔合增稠系统的差异。通过伯胺与MAEVE在有机溶剂中的反应和在碱水溶液中的水解来实现改性。这种独特的方法允许用疏水和荧光基团进行化学计量修饰。分子内缔合在广泛的环境中占主导地位。这些相互作用发生的程度是有效地探测通过监测非辐射能量转移（NRET）之间的萘和芘基团共价键合到聚合物链。聚合物内NRET量子效率随pH降低而增加，因为链收缩成球形构象。互聚物NRET是独立的盐浓度，但聚合物内NRET稳步增加与[NaCl]作为屏蔽的电荷-电荷排斥收缩的线圈。在极端酸性和碱性环境中，互聚物NRET随着静电排斥被屏蔽或消除而增加。已经提出了一种机制，其中标记的聚合物胶束的压实结果在增强互聚物聚集由于疏水胶束表面的形成。
A series of labeled, hydrophobically modified polymers based on the alternating copolymer of maleic anhydride and ethyl vinyl ether (MAEVE) has been synthesized to specifically address the issue of differences in domain organization of closed, polysoap systems and open, associative-thickening systems. Modification was achieved by reaction of primary amines with MAEVE in organic solvent and hydrolysis in aqueous base. This unique method allows stoichiometic modification with hydrophobic and fluorescent groups. Intramolecular associations predominate in a wide range of environments. The extent to which these interactions occur is effectively probed by monitoring nonradiative energy transfer (NRET) between naphthalene and pyrene groups covalently bound to the polymer chain. Intrapolymer NRET quantum efficiency increases with decreasing pH as the chain contracts to a globular conformation. Interpolymer NRET is independent of salt concentration, but intrapolymer NRET steadily increases with [NaCl] as the shielding of charge-charge repulsions constricts the coil. In extremely acidic and basic environments, interpolymer NRET increases as electrostatic repulsions are shielded or eliminated. A mechanism has been proposed whereby the compaction of labeled polymer micelles results in an enhancement in interpolymer aggregation due to the formation of hydrophobic micellar surfaces.