JST ERATO Takahara Soft Interfaces Project, CE80, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, Japan.
Faraday Discuss. 2012;156:403-12; discussion 413-34. doi: 10.1039/c2fd00123c.
Surface-initiated controlled radical copolymerizations of 2-dimethylaminoethyl methacrylate (DMAEMA), 2-(methacryloyloxy)ethyl phosphorylcholine (MPC), 2-(methacryloyloxy)ethyltrimethylammonium chloride) (MTAC), and 3-sulfopropyl methacrylate potassium salt (SPMK) were carried out on a silicon wafer and glass ball to prepare polyelectrolyte brushes with excellent water wettability. The frictional coefficient of the polymer brushes was recorded on a ball-on-plate type tribometer by linear reciprocating motion of the brush specimen at a selected velocity of 1.5 x 10(-3) m s-1 under a normal load of 0.49 N applied to the stationary glass ball (d = 10 mm) at 298 K. The poly(DMAEMA-co-MPC) brush partially cross-linked by bis(2-iodoethoxy)ethane maintained a relatively low friction coefficient around 0.13 under humid air (RH > 75%) even after 200 friction cycles. The poly(SPMK) brush revealed an extremely low friction coefficient around 0.01 even after 450 friction cycles. We supposed that the abrasion of the brush was prevented owing to the good affinity of the poly(SPMK) brush for water forming a water lubrication layer, and electrostatic repulsive interactions among the brushes bearing sulfonic acid groups. Furthermore, the poly(SPMK-co-MTAC) brush with a chemically cross-linked structure showed a stable low friction coefficient in water even after 1400 friction cycles under a normal load of 139 MPa, indicating that the cross-linking structure improved the wear resistance of the brush layer.
在硅片和玻璃球上进行了 2-二甲氨基乙基甲基丙烯酸酯 (DMAEMA)、2-(甲基丙烯酰氧基)乙基磷酸胆碱 (MPC)、2-(甲基丙烯酰氧基)乙基三甲基氯化铵 (MTAC) 和 3-磺丙基甲基丙烯酸钾盐 (SPMK) 的表面引发可控自由基共聚反应，制备了具有优异润湿性的聚电解质刷。在 298 K 下，以 1.5 x 10(-3) m s-1 的选定速度通过线性往复运动，在 0.49 N 的恒定负载下对固定的玻璃球（d = 10 mm）进行摩擦，在球盘式摩擦计上记录聚合物刷的摩擦系数。用双(2-碘乙氧基)乙烷部分交联的聚(DMAEMA-co-MPC)刷在相对湿度 (RH > 75%) 的潮湿空气中保持相对较低的摩擦系数约 0.13，即使在经过 200 次摩擦循环后也是如此。聚(SPMK)刷在经过 450 次摩擦循环后，摩擦系数仍低至 0.01。我们推测，由于聚(SPMK)刷对水的良好亲和力形成水润滑层，以及带有磺酸基团的刷之间的静电排斥相互作用，防止了刷的磨损。此外，具有化学交联结构的聚(SPMK-co-MTAC)刷在 139 MPa 的恒定负载下，在水中经过 1400 次摩擦循环后仍表现出稳定的低摩擦系数，表明交联结构提高了刷层的耐磨性。
