A MOLECULAR DYNAMICS STUDY OF ADHESION CHARACTERISTICS BETWEEN POLY(METHYLMETHACRYLATE) AND BARE SiO{sub}2/SiO{sub}2 COATED WITH SELF-ASSEMBLED MONOLAYERS

摘要

Self-assembled monolayers (SAMs) have attracted wide interests as anti-sticking layers in various micro/nano systems related with direct contacts, such as nanoimprint lithography (NIL). In this study, adhesion characteristics between polymethylmethacrylate) (PMMA) and bare SiO{sub}2/SiO{sub}2 coated with various SAMs are examined through molecular dynamics simulation. Amorphous SiO{sub}2, a-quartz SiO{sub}2, and alkylsilane SAMs with different chain lengths and eng-group are modeled using BKS potential, OPLS force field and newly developed torsion potential for Si atom in alkylsilane using ab initio calculation. As simulation results, the adhesion forces curves are plotted and separation processes are observed between PMMA and bare SiO{sub}2/SAM. Simulation results indicate that SAMs are effective to reduce adhesion and prevent the fracture of polymer film. It is also found that adhesion characteristics depend on SAM density and separation velocity, because they affect real contact area, SAM stiffness, and relaxation time of SAM rearrangement.