Abstract

Polydopamine is formed via dopamine hydrochloride (DAH) polymerization in a slightly alkaline medium (pH 8.5) both in a solution bulk and at a liquid–gas interface. Atmospheric oxygen and oxygen dissolved in the bulk solution serves as an oxidizing agent. Compression isotherms of polydopamine films formed at the interface for different times at different initial DAH concentrations have been determined in this work. Initial concentration of DAH affects the rate of polydopamine film formation; however, it weakly affects the film structure. At a low DAH concentration (1 g/L) and a long surface lifetime (720 min), the compression isotherms and the dependences of the static surface elasticity on the surface pressure turn out to be close to corresponding dependences for polydopamine films formed at a relatively high DAH concentration (5 g/L) and a shorter surface lifetime (240 min). The dependences of the static surface elasticity on the surface pressure appear to be nonmonotonic in contrast to the corresponding dependences of dynamic surface elasticity. In the first case, significantly higher values of the surface pressure are achieved; however, in the region of low surface pressures (<7 mN/m), the results are close to each other. The maximum static surface elasticity for continuous uniform polydopamine films is 150 mN/m. Upon a further compression, such films begin to collapse with the formation of a three-dimensional multilayer structure.

中文翻译：

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聚多巴胺薄膜的压缩等温线

摘要

聚多巴胺是通过多巴胺盐酸盐（DAH）聚合在溶液溶液中和液-气界面处的弱碱性介质（pH 8.5）中形成的。大气中的氧气和溶解在本体溶液中的氧气用作氧化剂。在这项工作中，已经确定了在不同初始DAH浓度下在界面上形成的聚多巴胺薄膜在不同时间的压缩等温线。DAH的初始浓度会影响聚多巴胺薄膜的形成速度；但是，它对薄膜结构的影响很小。在低DAH浓度（1 g / L）和长表面寿命（720分钟）下，结果表明，在较高DAH浓度（5 g / L）和较短表面寿命（240分钟）下形成的聚多巴胺薄膜，压缩等温线和静态表面弹性对表面压力的依赖性接近于相应的依赖性。与动态表面弹性的相应依赖性相反，静态表面弹性对表面压力的依赖性似乎是非单调的。在第一种情况下，可以实现更高的表面压力值。但是，在低表面压力（<7 mN / m）的区域中，结果彼此接近。连续均匀的聚多巴胺薄膜的最大静态表面弹性为150 mN / m。进一步压缩后，此类薄膜开始塌陷，形成了三维多层结构。