High Thermal Conductivity Polymer Blend Films with Excellent Mechanical and Recyclable Properties Based on Hydrogen Bonding Interactions

Poly(vinyl alcohol) (PVA) composite materials combine high thermal conductivity with excellent flexibility, making them popular in the thermal management field. To enhance the thermal conductivity of materials, two polyesters of pyridine and quinoline containing hydrogen bond acceptors were synthesized and named B and K, respectively. The simultaneous enhancement of thermal conductivity and flexibility was achieved by constructing ordered structures through blending with PVA. The thermal conductivity of the 20B@PVA film was 2.53 W m–1 K–1, which is 12.6 times higher than that of pure PVA (0.20 W m–1 K–1). Meanwhile, it exhibits excellent elongation at break of 453%, improving by 2.42 times compared to pure PVA (187%). The thermal conductivity of the 20K@PVA film was 2.25 W m–1 K–1, which is 11.3 times higher than that of pure PVA. Due to the higher rigidity of the quinoline unit, its molecular chains exhibit highly ordered alignment, resulting in a fracture elongation of 347% for the 20K@PVA film. A significant blue shift of the absorption peak of the −OH group in the blended film 20B@PVA (from 3426 cm–1 to 3298 cm–1) was observed in the FTIR spectra, suggesting strong interaction between polymer B and PVA. Stronger hydrogen bonding interactions can form more stable heat conduction pathways, reduce phonon scattering, and enhance thermal conductivity. Furthermore, to avoid waste and environmental pollution, PVA was recycled and the recovery rate reached 78.5%.