title: The interlayer swelling and molecular packing in organoclays.
abstract: Understanding the interlayer swelling and molecular packing in organoclays is important to the formation and design of polymer nanocomposites. This paper presents recent experimental and molecular simulation studies on a variety of organoclays that show a linear relationship between the increase of d-spacing and the mass ratio between organic and clay. A denser molecular packing is observed in organoclays containing surfactants with hydroxyl-ethyl units. Moreover, our simulation results show that the head (nitrogen) groups are essentially tethered to the clay surface while the long hydrocarbon chains tend to adopt a layering structure with disordered conformation, which contrasts with the previous assumptions of either the chains lying parallel to the clay surface or being tilted at rather precise angles.
authors: Department of Chemical Engineering, University of Texas at Austin, TX 78712, USA. drp@che.utexas.edu
authors: D R
authors: DR
authors: Paul
authors: Q H
authors: QH
authors: Zeng
authors: A B
authors: AB
authors: Yu
authors: G Q
authors: GQ
authors: Lu