聚乙二醇在硅酸二钙表面吸附的分子动力学模拟

Molecular dynamics simulation of adsorption of polyethylene glycol on surface of dicalcium silicate

采用分子动力学模拟研究了在真空和水溶液环境下聚乙二醇在β-2CaO.SiO2表面吸附的规律及其机理。在真空环境下聚乙二醇与β-2CaO.SiO2不同晶面的吸附强弱顺序依次为:(110)>(010)>(011)>(001)≈(101)>(100);而在水溶液环境下其吸附强弱顺序为:(010)≈(110)≈(001)>(011)>(101)(100)。真空和水溶液环境下在343～363K时温度对聚乙二醇与β-2CaO.SiO2(110)晶面相互作用时的单位面积吸附能影响不大,但当在聚合物链节数较小时单位面积吸附能随链节数的增加而明显增加。在水溶液的环境中,分别构造了β-2CaO.SiO2和聚乙二醇与水分子的径向分布函数,水分子与聚合物、β-2CaO.SiO2表面之间都存在吸附能,由于水分子较小,其对聚合物与晶面的吸附产生排斥作用,导致聚合物在水环境中与硅酸二钙晶体吸附能降低。

The adsorption of polyethylene glycol on the surface of calcium silicate under vacuum and water environments was studied using molecular dynamics simulation. The results indicated that the adsorption ability of polyethylene glycol at （110） layer of β-2CaO · SiO2 was stronger than other layers. Temperature had little effect on adsorption energy of β-2CaO ·SiO2 and polyethylene glycol between 343--363 K, but chain length of polyethylene glycol affected adsorption energy obviously when chain length was short. Because of adsorption energy between water molecule and polymer/crystal surface, adsorption energy of polyethylene glycol on the surface of calcium aluminate decreased. The results of distribution functions indicated that strong hydrogen bond was formed between O of polyethylene glycol and Hw of water.