Interlayer Structure and Bonding in Nonswelling Primary Amine Intercalated Clays

Abstract

Preparation of industrially useful clay−polymer nanocomposite materials often requires the dispersal of clay particles within a polymer matrix. The degree to which the clay particles may be dispersed has an effect on the resultant properties of the material, and the clay is often rendered organophilic using alkylammonium species to facilitate incorporation of polymer. The use of a low molecular weight poly(propylene) oxide diamine is investigated as a reagent for controlling the separation between layers in smectite clays and therefore the extent to which the clay tactoid may be dispersed. The arrangement and interactions of the amine species in the interlayer region are investigated through analysis by both experimental methods and computer simulation, which gives insight into coordination mechanisms within the organoclay. Infrared spectroscopy indicates the presence of extensive hydrogen bonding within the amine−clay interlayer. Some of the amine species were found to intercalate in a nonprotonated state, resulting in strong hydrogen-bonding interactions between amine and ammonium groups. Large-scale classical molecular dynamics simulation shows that the amine groups do not interact strongly with the clay sheets, in contradistinction to ammonium groups. The effect of simulation cell size was considered, and in the limit of zero finite size effects, physically realistic undulations are observed within the individual clay sheets.

Effects of layer-charge distribution on the thermodynamic and microscopic properties of Cs-smectite

“…For example, it is found that ammonium cations always bind to H-sites rather than Tsites in organo-clay nanocomposite (Greenwell et al, 2005;Liu et al, 2007). Furthermore, this finding can be easily applied to other phyllosilicate members.…”

Combined experimental and theoretical investigation of interactions between kaolinite inner surface and intercalated dimethyl sulfoxide

“…In our simulation cases, the recently developed INTER-FACE force field [30,31] was adopted, which has already been proven quite successful in describing many inorganic-organic and inorganic-bimolecular interfaces, especially for clays, in quantitative agreement with available experimental data [30,[32][33][34][35][36][37][38][39][40][41][42]. The force field parameters of our systems were summarized in detail in Ref.…”

Structure and dynamic properties of water saturated CTMA-montmorillonite: molecular dynamics simulations

“…Recently, molecular simulations were introduced into the study of the structure of dried OC and proved to be powerful methods in complementing experiments, especially in probing the details about molecular arrangements and conformations at the atomic level (Greenwell et al, 2005;Hackett et al, 1998;He et al, 2005;Heinz et al, 2003Heinz et al, , 2005Heinz et al, , 2007Liu et al, 2007;Tambach et al, 2006;Zeng and Yu, 2008;Zeng et al, 2003Zeng et al, , 2004. Layered arrangements of alkylammonium chains in the interlayer space of montmorillonite (Mt) have been discovered in several studies (Heinz et al, 2003(Heinz et al, , 2005(Heinz et al, , 2007Zeng and Yu, 2008;Zeng et al, 2004).…”