Structure and phase transitions of alkyl chains on mica.

摘要: We use molecular dynamics as a tool to understand the structure and phase transitions [Osman, M. A.; et al. J. Phys. Chem. B 2000, 104, 4433−4439. Osman, 2002, 106, 653−662] in alkylammonium micas. The consistent force field 91 is extended for accurate simulation of mica related minerals. investigate sheets with 12 octadecyltrimethylammonium (C18) ions or dioctadecyldimethylammonium (2C18) ions, respectively, single layered structures at different temperatures periodicity xy plane by NVT dynamics. reside preferably above cavities surface an aluminum-rich boundary. nitrogen atoms are 380−390 pm away from superficial silicon−aluminum plane. With increasing temperature, rearrangements C18 on found, while 2C18 remain tethered due geometric restraints. present basal-plane spacings duplicate structures, tilt angles alkyl chains, gauche−tra...