Connection Length Controlled Sound Speed and Thermal Conductivity of Hybrid Metalcone Films.

The multifaceted applications of polymers are often limited by their thermal conductivity. Therefore, understanding the mechanisms of thermal transport in polymers is of vital interest. Here, we leverage molecular layer deposition to grow three types of hybrid metalcone (i.e., alucone, zincone, and tincone) films and study their thermal and acoustic properties. The thermal conductivity of the hybrid polymer films ranged from 0.43 to 1.14 W m K. Using kinetic theory, we trace the origin of thermal conductivity difference to sound speed change, which is dictated by the connection length within the films. Changing the connection length has negligible impacts on volumetric heat capacity and vibrational lifetimes. Our findings provide means to improve the thermal conductivity of organic, hybrid, and inorganic polymer films.