Molecular dynamics study of adsorption of fluoric polymers on TATB surface

Molecular dynamics simulation has been applied to study the adsorption process of PVDF/PCTFE copolymers on TATB (001) surfaces. The copolymers were formed by linking PVDF and PCTFE in 1:1 proportion as ABABAB pattern with the degree of polymerization N ranging from 10 to 200. The equilibrium time of each chain is several hundred picoseconds, and the adsorption energy E_a increases with the distance H between the chain and the increased surface. Adsorption process occurs when H is below 10 Å, and E_a tends to be zero as H becomes greater than 10 Å. Polymer's adsorbability is related to the length of the chain, and a longer chain is better than a short one. A short chain has more train conformation monomers than a long chain. Chain conformation changes greatly during the first hundred ps, and stabilizes after 150 ps. Monomers close to the TATB surface are easy to approach the surface, and the units far from the surface will approach the surface by chain torsion and bond rotation. The ratio of the number of train conformation monomers to the degree of polymerization N_t/N increases with the increasing MD simulation time.