Predicting the Mechanical Response of Polyhydroxyalkanoate Biopolymers Using Molecular Dynamics Simulations

Area of Science:

• Polymer Science
• Materials Science
• Computational Chemistry

Background:

• Polyhydroxyalkanoates (PHAs) are biodegradable polymers with potential to replace petroleum-based plastics.
• Established structure-property relationships are crucial for tailoring PHA mechanical performance.
• Experimental data on PHA mechanical properties is limited, necessitating predictive methods.

Purpose of the Study:

• To predict chemical trends in mechanical properties of diverse PHAs using molecular dynamics simulations.
• To investigate the influence of backbone length, side chain length, and side chain functional groups on PHA mechanical behavior.
• To explore the composition-dependence of mechanical properties in PHA copolymers.

Main Methods:

• Utilized molecular dynamics simulations with a novel force field.
• Performed deformation simulations across various strain rates and temperatures.
• Analyzed Young's modulus and yield stress for a range of PHA structures and copolymers.

Main Results:

• Young's modulus and yield stress decrease with increasing carbon atoms in PHA side chains and backbones.
• Mechanical properties strongly correlate with side chain functional groups, with enhanced interchain interactions improving strength.
• Methodology successfully predicted composition-dependent mechanical properties for binary and ternary PHA copolymers.

Conclusions:

• Established rational design rules for tailoring PHA mechanical properties.
• Highlighted the importance of side chain chemistry and length in determining mechanical performance.
• Opened avenues for high-throughput simulations to discover novel PHA candidates for specific applications.