Packing Morphologies of Phenyltrichlorosilane on the Substrate of SiO2 and Their Effects on the Molecular Conformation of Polythiophene and Poly(3-hexylthiophene)
Date Issued
2012
Date
2012
Author(s)
Shih, Sheng-Yang
Abstract
We employ the all-atom molecular dynamic simulation and the theoretical calculations to study the conformation of four different grafting density (25%、50%、75% and 100%) of phenyltrichlorosilane (PTS) and its interaction among polythiophene (PT) and poly(3-hexylthiophene). In the beginning ,we use Monte Carlo method to find the absorption site between benzene ring, thiophene ring, and 3-hexylthiophene ring to support our discussion later. In the second part, we graft four grafting density PTS on the SiO2 substrate and studied their conformation. We find that the conformation of PTS becoming dense and packing well-ordered because the π-π interaction and π-H interaction will be strong with increasing of grafting density. In the third part we investigate the interaction between PT/P3HT and grafted system. When grafting density is 25%, we find that PT will insert the vacant space between grafting silanes and there is an elevation angle between PT and substrate. When grafting density reaching 50%, we find PT will insert the vacant space by perpendicular to the substrate, and the elevation angle will increase, the coplanarity will decrease. At high grafting density, the vacant space between grafting silanes is too narrow to let PT insert, so PT will lay on the surface of grafting silanes, the elevation angle will decrease, the coplanarity will increase. At last, we investigate the interaction between P3HT and grafted system. At low grafting density, alkyl chain will extend into the vacant space, the thiophene ring can still make π-π interaction with benzene ring. However, the disturbance of alkyl chain will cause elevation angle smaller than PT’s, and coplanarity is also small because of the insertion of alkyl chain. With the increasing of grafting density, the vacant space is already too narrow to let P3HT insert, so P3HT will lay on the surface of grafting silanes, the elevation angle will decrease, the coplanarity will increase. At the highest grafting density, P3HT still lay on the surface of grafting silanes, so the elevation angle becoming smaller, and the coplanarity is still fine.
Subjects
Molecular dynamics
SiO2
P3HT
Type
thesis
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