利用和频振动光谱及表面张力测定技术对两亲性聚氧乙烯-聚氧丙烯(PEO-PPO)表面活性剂的表面活性及溶液界面结构进行了研究。结果表明:疏水PPO链段在溶液界面吸附并紧密排列是溶液表面张力降低的主要原因。增加溶液浓度、增大共聚物链内PPO与PEO聚合度比值可增加高分子链在界面的吸附,并使PPO在界面紧密排列,侧基(甲基)有序取向。另外,PPO在分子链中的位置也对这一行为产生影响,PPO位于分子链两端时的结构更有利于PPO在表面紧密堆积,降低界面高分子链间相互作用,减小溶液表面张力。
Surface tension of polyether surfactant (PEO PPO) with various chain structures was measured by surface tension measurement, and the local structure at the air/solution interface was investigated by the Sum Frequency Generation vibrational spectroscopy ( SFG). The relationships between the locally interfacial structure and the surface activity of PEO-PPO surfactant were elucidated. The closely packing of PPO segments and well-ordered orientation of methyl group at the air/solution interface are responsible for the surface tension reduction of polymer solution. With the increasing of solution concentration and the molar ratio of PPO and PEO blocks(nppo/npEo ) ,more PPO segments were segregated onto the surface and closely packed, and the methyl groups in PPO units orientated more orderly. Meanwhile , the copolymer with PPO block at the chain ends is easier to enrich to the surface,and thus is more efficient to reduce the surface tension.