Friction behavior of high-density poly(2-methacryloyloxyethyl phosphorylcholine) brush in aqueous media
Friction behavior of high-density poly(2-methacryloyloxyethyl phosphorylcholine) brush in aqueous media
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DOI：
10.1039/b615780g
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发表时间：
2007-01-01
期刊：
影响因子：
3.4
通讯作者：
Takahara, Atsushi
中科院分区：
文献类型：
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作者：
Kobayashi, Motoyasu;Terayama, Yuki;Takahara, Atsushi
以2-甲基丙烯酰氧乙基磷酰胆碱(MPC)为原料，通过表面引发原子转移自由基聚合，在引发剂固定的硅片上制备了超亲水聚合物刷子。根据M-n与层厚度之间的线性关系，估算出接枝密度约为0.22链nm(-2)。与水的接触角很小，水中的气泡几乎不附着在刷子表面，表明表面是超亲水的。聚(MPC)刷的中子反射率测量表明，在良好的溶剂(如水)中，接枝的聚合物链在垂直方向上从衬底延伸了相当多的量，而在较差的溶剂中则收缩。用玻璃球探头在空气和各种溶剂中以90 mm min(-1)的滑动速度在0.49 N的载荷下滑动，表征了聚(MPC)电刷的摩擦性能。由于吸附在刷层中的水分子起到了润滑剂的作用，聚(MPC)刷子在潮湿的空气中具有极低的摩擦系数。
Super-hydrophilic polymer brushes were prepared by surface-initiated atom transfer radical polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) on initiator-immobilized silicon wafers. The graft density was estimated to be ca. 0.22 chains nm(-2) based on the linear relationship between M-n and the layer thickness. The contact angle against water was very low, and air bubbles in water hardly attached onto the brush surface, indicating a super-hydrophilic surface. Neutron reflectivity measurements of the poly( MPC) brush showed that the grafting polymer chains extended a fair amount in the vertical direction from the substrate in a good solvent such as water, while they shrunk in a poor solvent. Frictional properties of the poly( MPC) brushes were characterized by sliding a glass ball probe in air and various solvents under a load of 0.49 N at a sliding velocity of 90 mm min(-1). An extremely low friction coefficient of the poly( MPC) brush was observed in humid atmosphere because water molecules adsorbed into the brush layer acted as a lubricant.