Roles of specific hydrogen-bonding interactions in the crystallization kinetics of polymers

Polyamides hold specific hydrogen-bonding interactions as the hierarchical thermodynamic driving forces for crystallization. Their roles in crystallization kinetics are worthy of further investigation. We performed dynamic Monte Carlo simulations to compare crystallization kinetics among 16-mer melts holding hydrogen-bonding interactions with variable strengths specifically assigned to 2, 4 and 8 monomers on the chain, respectively. The results demonstrate higher densities and strengths of hydrogen-bonding interactions generally accelerating the cooling and isothermal crystallization as well as the lateral growth of lamellar crystals, consistent with the experimental observations of polyamide crystallization. Too strong hydrogen-bonding interactions will slow down polymer diffusion and thus bring retardation to crystallization kinetics. Furthermore, hydrogen-bonding interactions at the central 8–9 monomers make higher crystal growth rates than those at the evenly distributed 5–12 monomers, demonstrating the dominant roles of specific interactions in the hierarchical parallel packing of polymer chains at the lateral growth front of lamellar crystals.