Surface Structures of PDMS Incorporated with Quaternary Ammonium Salts Designed for Antibiofouling and Fouling Release Applications
Surface Structures of PDMS Incorporated with Quaternary Ammonium Salts Designed for Antibiofouling and Fouling Release Applications
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DOI：
10.1021/la304571u
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发表时间：
2013-03-05
期刊：
影响因子：
3.9
通讯作者：
Chen, Zhan
中科院分区：
文献类型：
--
作者：
Liu, Yuwei;Leng, Chuan;Chen, Zhan
聚二甲基硅氧烷（PDMS）材料在海洋环境中被广泛证明是一种优异的防污涂料。加入杀菌剂部分，如季铵盐（QAS），可以赋予pdm基FR涂层系统额外的抗污性能。本研究利用和频产生振动光谱（SFG）研究了两种不同类型的qas - PDMS体系在不同化学环境下的分子表面结构。在空气、水和人工海水（ASW）中，用SFG测量了含有单个铵盐基团的QAS或季铵功能化多面体低聚硅氧烷（QPOSS）的PDMS涂层，研究了这些材料的界面表面结构与其防污性能之间的关系。虽然以前的研究表明，上述材料是很有前途的接触活性防污涂料，但QAS结构的微小变化会导致防污性能的实质性差异。事实上，SFG的结果表明，这些材料的表面结构取决于几个因素，如季铵化程度、PDMS组分的分子量和用于掺入PDMS矩阵的QAS的官能团。结果表明，在水环境中，较低的QPOSS季铵化程度和使用乙氧基（而不是甲氧基）官能团加入QAS有利于烷基链从表面的氮原子向外延伸。SFG的结果与防污活性的研究结果相吻合，这些研究表明，从表面伸出的较长的烷基链浓度较低的涂层可以更有效地中和微生物，最终导致更好的防污性能。此外，本研究的结果提供了额外的证据，证明掺入的QAS通过两步相互作用发挥其抗菌活性。第一步是细菌在表面的吸附，这是由于带负电荷的微生物与表面带正电荷的QAS氮原子之间的静电吸引。第二步是通过QAS长延伸烷基链的渗透破坏细胞膜。
Poly(dimethylsiloxane) (PDMS) materials have been extensively shown to function as excellent fouling-release (FR) coatings in the marine environment. The incorporation of biocide moieties, such as quaternary ammonium salts (QAS), can impart additional antibiofouling properties to PDMS-based FR coating systems. In this study, the molecular surface structures of two different types of QAS-incorporated PDMS systems were investigated in different chemical environments using sum frequency generation vibrational spectroscopy (SFG). Specifically, a series of PDMS coatings containing either a QAS with a single ammonium salt group per molecule or a quaternary ammonium-functionalized polyhedral oligomeric silsesquioxane (QPOSS) were measured with SFG in air, water, and artificial seawater (ASW) to investigate the relationships between the interfacial surface structures of these materials and their antifouling properties. Although previous studies have shown that the above-mentioned materials are promising contact-active antifouling coatings, slight variations of the QAS structure can lead to substantial differences in the antifouling performance. Indeed, the SFG results presented here indicated that the surface structures of these materials depend on several factors, such as the extent of quaternization, the molecular weight of the PDMS component, and the functional groups of the QAS used for incorporation into the PDMS matrix. It was concluded that in aqueous environments a lower extent of QPOSS quaternization and the use of ethoxy (instead of methoxy) functional groups for QAS incorporation facilitated the extension of the alkyl chains away from the nitrogen atom of the QAS on the surface. The SFG results correlated well with the antifouling activity studies that indicated that the coatings exhibiting a lower concentration of longer alkyl chains protruding out of the surface can neutralize microorganisms more effectively, ultimately leading to better antifouling performance. Furthermore, the results of this study provide additional evidence that incorporated QAS exert their antimicrobial activity through a two-step interaction. The first step is the adsorption of the bacteria on the surface as a result of the electrostatic attraction between the negatively charged microorganisms and the positively charged QAS nitrogen atoms on the surface. The second step is the disruption of the cell membranes by the penetration of the QAS long, extended alkyl chains.