  The relatively low thermal conductivity of biodegradable polylactic acid
(PLA) has limited its applications in various fields. To address this issue,
the incorporation of nanofillers, such as boron nitride nanosheets (BNNSs), has
emerged as an effective method to enhance PLA's thermal properties. However,
the thermal conduction of polymer-based nanocomposites is strongly influenced
by interfacial thermal resistance. In this study, we investigate the impact of
pristine and surface-treated BNNSs on the thermal behavior of PLA using
molecular dynamics simulations. To enhance interfacial interactions and reduce
chain mobility during heat transfer, we chemically modify the surface of BNNSs
by introducing three different functional groups (NH2, OH, and COOH) with
varying polarities. Our findings suggest that oxygen-containing groups, namely
OH and COOH, exhibit stronger interfacial interactions compared to the other
cases. We also systematically apply different percentages of these functional
groups (i.e., 2.5, 5, and 7.5) and observe that a higher number of functional
groups leads to a greater improvement in interfacial thermal transport,
attributed to the enhanced phonon coupling effect. To complete the discussion,
we thoroughly study the influence of random and agglomerated patterns of
functional groups distribution.
