Application of Molecular Dynamics Simulation on Poly(phenylene oxide) and Polyethylene

• Main Authors: Chen, Hsin-lang, 陳幸郎
• Other Authors: Chen, Cheng-lung
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/27925642228206871962

博士 === 國立中山大學 === 化學學系 === 82 === Molecular dynamics (MD) simulation of a simple phenylene polymer, poly(phenylene oxide) (PPO), was carried out with the TRIPOS 5.2 force field. Two types of molecular motion were examined: rotation of individual phenylene rings and torsion of a large segment (i.e. four-oxygen segment, FOS) involving four ether oxygen atoms and three phenylene rings. Model compounds, diphenyl ether and 1,4-bis(4-phenoxy phenoxy) benzene, were used to help the analysis of the result. Based on the trajectory analysis, "in-phase" cooperative rotations of the neighboring phenylene rings and "out-of-phase" cooperative rotations of consecutive FOS''s, superimposed on random segmental wiggles, were observed. Packing effect was found to be important for the larger FOS rotations but not for the rotation of individual rings. The diffusion coefficient for the torsion of an FOS is about half of that for the rotation of an individual phenylene ring, but remains within the same order-of- magnitude. Another, the behavior of energy flow in a model chain of amorphous polyethylene is discussed. The rate of energy flow through the backbone of a polyethylene chain was studied as functions of density, stretching force constant, and temperature. It is found that the energy flow rate is fast initially and becomes slower in later time. The dispersion of excitation energy is found to be accelerated by the energy transfer through nonbonded interactions. The rate of energy flow is also sensitive to the stretching force constant and temperature of the system.