  Polymers are usually considered as thermal insulators and their applications
are limited by their low thermal conductivity. However, recent studies showed
that certain polymers have surprisingly high thermal conductivity, some of
which are comparable to that in poor metals or even silicon. In this review, we
outline the experimental achievements and theoretical progress of thermal
transport in polymers and their nanocomposites. The open questions and
challenges of existing theories are discussed. Special attention is given to
the mechanism of thermal transport, the enhancement of thermal conductivity in
polymer nanocomposites/fibers, and their potential application as thermal
interface materials.
