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Molecular modeling study on surface,thermal, mechanical and gas diffusion properties of chitosan
Authors:B. Prathab  Tejraj M. Aminabhavi
Affiliation:1. Molecular Modeling Division, Center of Excellence in Polymer Science, Karnatak University, Dharwad 580 003, India;2. Molecular Modeling Division, Center of Excellence in Polymer Science, Karnatak University, Dharwad 580 003, IndiaMolecular Modeling Division, Center of Excellence in Polymer Science, Karnatak University, Dharwad 580 003, India
Abstract:The motivation of this work is to provide reliable and accurate modeling studies of the physical (surface, thermal, mechanical and gas diffusion) properties of chitosan (CS) polymer. Our computational efforts have been devoted to make a comparison of the structural bulk properties of CS with similar type of polymers such as chitin and cellulose through cohesive energy density, solubility parameter, hydrogen bonding, and free volume distribution calculations. Atomistic modeling on CS polymer using molecular mechanics (MM) and molecular dynamics (MD) simulations has been carried out in three dimensionally periodic and effective two dimensionally periodic condensed phases. From the equilibrated structures, surface energies were computed. The equilibrium structure of the films shows an interior region of mass density close to the value in the bulk state. Various components of energetic interactions have been examined in detail to acquire a better insight into the interactions between bulk structure and the film surface. MD simulation (NPT ensemble) has also been used to obtain polymer specific volume as a function of temperature. It is demonstrated that these VT curves can be used to locate the volumetric glass transition temperature (Tg) reliably. The mechanical properties of CS have been obtained using the strain deformation method. Diffusion coefficients of O2, N2, and CO2 gas molecules at 300 K in CS have been estimated. The calculated properties of CS are comparable with the experimental values reported in the literature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1260–1270, 2007
Keywords:chitosan  diffusion  glass transition temperature  surface energy
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