PVP调控花状碳酸铈堆积过程的分子动力学模拟

Molecular Dynamics Simulation of PVP Regulating Process of Flowering Cerium Carbonate Stacking

采用聚乙烯吡咯烷酮(PVP)为模板剂,利用Material Studio软件研究Ce_(2)(CO_(3))_(3)·8H_(2)O晶体陈化堆积过程的生长机制。通过对Ce_(2)(CO_(3))_(3)·8H_(2)O各晶面间Ce^(3+)间距和PVP分子链上不同酮基间间距进行分子动力学模拟,解释PVP在Ce_(2)(CO_(3))_(3)·8H_(2)O各晶面间的吸附识别过程。在模拟的水环境中,得到PVP最优的空间构型,并通过模拟过程中温度和势能变化,PVP与Ce_(2)(CO_(3))_(3)·8H_(2)O晶面的结合能与形变能,从能量的角度解释了PVP与Ce_(2)(CO_(3))_(3)·8H_(2)O结晶面之间相互作用关系中PVP调节Ce_(2)(CO_(3))_(3)·8H_(2)O形态的作用机制。结果表明:Ce_(2)(CO_(3))_(3)·8H_(2)O的(002),(040)和(240)晶面都极易吸附PVP分子;其中Ce_(2)(CO_(3))_(3)·8H_(2)O晶体的(002)晶面的吸附能大于(040),(240)两个晶面,吸附PVP分子量最高;随着碳铵的不断添加,Ce_(2)(CO_(3))_(3)·8H_(2)O晶体的逐渐生长,在PVP分子的牵引缠绕作用下,Ce_(2)(CO_(3))_(3)·8H_(2)O晶体之间逐渐靠近,最终团聚成花状的Ce_(2)(CO_(3))_(3)·8H_(2)O晶体。

Using polyvinylpyrrolidone(PVP)as the template,the Material Studio software was used to study the growth mechanism of cerium carbonate crystal aging and accumulation.Through molecular dynamics simulation of the Ce^(3+)spacing between the crystal faces of cerium carbonate and the spacing between different ketone groups on the PVP molecular chain,the adsorption recognition process of PVP on the crystal faces of cerium carbonate was explained.In the simulated water environment,the optimal spatial configuration of PVP is obtained,and the temperature and potential energy changes during the simulation process,the binding energy and deformation energy of the PVP and the cerium carbonate crystal plane,explain the crystallization of PVP and cerium carbonate from the energy point of view the mechanism by which PVP regulates the morphology of cerium carbonate in the interaction relationship between the surfaces.The results show that the(002),(040)and(240)crystal planes of cerium carbonate are very easy to adsorb PVP molecules;among them,the(002)crystal plane of cerium carbonate crystals has higher adsorption energy than that of the(040)and(240)crystal planes.With the continuous addition of ammonium bicarbonate,the cerium carbonate crystals gradually grow.Under the traction and winding action of the PVP molecules,the cerium carbonate crystals gradually approach each other,and finally agglomerate into flower-like cerium carbonate crystals.