Polyhydroxyalkanoates
(PHAs), a promising class of biomaterials,
have gained considerable attention to replace petroleum-based plastics
owing to their excellent biocompatibility and biodegradability. Homopolymers
of PHA suffer from poor tunability in thermal and mechanical properties.
Going from homopolymers to copolymers, the design space can be substantially
enhanced by combining two or more monomers in different compositions
(i.e., relative ratios of the different monomers) and configurations
(i.e., relative positions of the different monomers in the polymer
backbone) leading to a substantially large chemical space where application-specific
optimization for the targeted functionality can be performed. However,
this composition and configuration dependence of properties in the
vast PHA copolymer chemical space remains largely unexplored. In this
contribution, further building on our past work with PHA homopolymers,
we systematically explore these chemical trends for glass-transition
temperature (T
g) in PHA copolymers and
blends. Our molecular dynamics simulations, utilizing a previously
validated force field for PHAs, suggest that these trends are largely
governed not only by the homopolymer T
g values but also configuration-dependent interchain interactions
in the copolymer system. In particular, our results indicate that
the configuration-dependent variation in the target property at a
fixed composition can be significant in the presence of hydrogen-bond-forming
monomers. These qualitative observations are further rationalized
by quantitatively analyzing various closely related atomic level descriptors
of copolymers and blends such as monomer mobility, number of hydrogen
bonds, and pair correlation functions. The findings presented in this
work help to develop a deeper atomistic-level understanding of thermomechanical
behavior of PHA-based copolymers and can potentially guide the rational
design of biopolymers as environmental-friendly functional materials.