Influence of hydrophobic terminal groups on mobility of polydimethylsiloxane chains: molecular dynamics simulation

Abstract

Polydimethylsiloxane-based materials can exhibit self-healing properties, most often at increased temperatures. To reduce the self-healing temperature, introduction of copolymer blocks engaging in additional reversible interactions is commonly used. However, this type of modification can significantly alter the functionally important physicochemical features of the original polymer. In this study, molecular dynamics simulations were used to test the idea of a milder modification which implies altering only one of the terminal groups of polymeric chains. This modification was expected to affect the migration dynamics of these groups between ionic aggregates, which we had revealed in previous studies. Indeed, in the resulting molecular dynamics simulations, a slight increase in the hydrophobicity of the terminal chain fragments ensures more active migration even at room temperature. However, an excessive hydrophobicity increase of the terminal groups reduces their chemical affinity to ionic aggregates. Thus, according to the molecular dynamics data, decrease of the self-healing temperature could be achieved by increasing the hydrophobicity of one of the terminal groups of the polydimethylsiloxane chains.