The study of polydimethylsiloxane nanocone distortion in the demolding process using molecular dynamics method

Abstract

Experimental results show that after demolding process from the polymethylmethacrylate mold, the poly(dimethlysiloxane) (PDMS) nanocone replica yields 150%–160% larger in height as compared to the mold size dimensions before rupture. The observation from the experiment gives the direction for this study to investigate the distortion of PDMS nanocone structures in the demolding soft lithography process using molecular dynamics simulation. The aim of this study is to employ the molecular dynamics simulations and study the stress–strain curve of the nanocone structures that were subjected to uniaxial stress. Two force fields (polymer consistent forcefield and condensed-phase optimized molecular potentials for atomistic simulation studies) were utilized for the modeling. The results from the molecular dynamics simulation show that when the PDMS nanocone is subjected to tensile stress, it shows characteristics of flexible plastic pattern curve with significant yielding. This study also found that ultimate tensile stress for PDMS nanocones is within the value found in the bulk structure of 4.335–6.478 MPa.