L-半胱氨酸自组装单层调控方解石的结晶取向

Orientation control of calcite via L-cysteine self-assembled monolayers

利用L-半胱氨酸自组装单层(L-Cys SAM)成功控制了方解石的结晶取向。XRD和SEM测试结果表明,方解石可以优先选择(104)或(001)晶面成核。Ca Cl2溶液的初始p H值对L-Cys SAM的调控行为有重要的影响。初始溶液p H值为6.0时,自组装单层上得到的方解石成核面主要为(001)晶面,择优取向程度达到95%。随着初始溶液p H值的提高,(104)晶面生长的方解石数量明显增加;初始溶液p H值为9.0时,(104)面择优取向方解石数量可高达98%。L-Cys SAM的结构也随溶液p H值发生变化。在低p H值条件下,L-Cys分子以两性离子形式存在,具有(槡槡3×3)R30°结构的SAM可以与方解石的(001)晶面完全匹配。在高p H值条件下,L-Cys分子的存在形式为-NH2和-COO-,因此,可以调控得到方解石的(104)晶面。

L-cysteine self-assembled monolayers （L-Cys SAM） were employed to control the growth orientation of calcite successfully. XRD and SEM results showed that the predominant orientation of （001） or （104） calcite can be obtained respectively. The pH of initial CaCl2 solution has a significant influence on the induced performance of L-cys SAM. At a low pH of 6. 0, the dominant nucleation face of the obtained calcite on SAM was （001）, and the percentage of （001） orientation crystals can reach a high level of 95%. With the pH increase of the initial CaCl2 solution, the （104） face crystals were enhanced significantly; when pH of the initial solution reach 98%. The structures of L-Cys SAMs c is about 9.0, the （104） preferred orientation crystals will hanges with the solution pH. At low pH, L-cysteine molecules exist in zwitterionic forms and SAM with the （√3×√3）R30°structure could perfectly match the （001） face of calcite. At high pH, the existence form of L-cysteine molecules became - NH2 and - COO^-, thus, the （104） face of calcite could be induced.