Department of Chemical Physics, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, P. R. China.; Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, P. R. China.
Department of Chemical Physics, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, P. R. China.
Sci Adv. 2016 Aug 5;2(8):e1600579. doi: 10.1126/sciadv.1600579. eCollection 2016 Aug.
Weak polyelectrolytes have found extensive practical applications owing to their rich pH-responsive properties. In contrast, strong polyelectrolytes have long been regarded as pH-insensitive based on the well-established fact that the average degree of charging of strong polyelectrolyte chains is independent of pH. The possible applications of strong polyelectrolytes in smart materials have, thus, been severely limited. However, we demonstrate that almost all important properties of strong polyelectrolyte brushes (SPBs), such as chain conformation, hydration, stiffness, surface wettability, lubricity, adhesion, and protein adsorption are sensitive to pH. The pH response originates from the reorganization of the interchain hydrogen bond network between the grafted chains, triggered by the pH-mediated adsorption-desorption equilibrium of hydronium or hydroxide with the brushes. The reorganization process is firmly identified by advanced sum-frequency generation vibrational spectroscopy. Our findings not only provide a new understanding of the fundamental properties of SPBs but also uncover an extensive family of building blocks for constructing pH-responsive materials.
弱聚电解质由于其丰富的 pH 响应特性而得到了广泛的实际应用。相比之下，由于强聚电解质链的平均电荷程度与 pH 无关这一既定事实，强聚电解质长期以来一直被认为对 pH 不敏感。因此，强聚电解质在智能材料中的可能应用受到了严重限制。然而，我们证明了强聚电解质刷（SPB）的几乎所有重要性质，如链构象、水合作用、刚性、表面润湿性、润滑性、粘附性和蛋白质吸附性，都对 pH 敏感。这种 pH 响应源于接枝链之间的链间氢键网络的重组，这是由与刷结合的质子或氢氧根离子的 pH 介导的吸附-解吸平衡所触发的。这种重组过程通过先进的和频发生振动光谱得到了明确的确认。我们的发现不仅为 SPB 的基本性质提供了新的认识，而且还揭示了构建 pH 响应材料的广泛的构建块家族。
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