Mussel-inspired polydopamine modification of bamboo flour for superior interfacial compatibility of bamboo plastic composites: influence of oxidant type

Bamboo flour (BF) was modified with mussel-inspired polydopamine adhesive coatings to achieve better compatibility with high-density polyethylene (HDPE) in BF/HDPE composites. Polydopamine was synthesized from dopamine by using various oxidants, e.g., O2, CuSO4, NaIO4, (NH4)2S2O8, and FeCl3. Modification improved physicochemical features of BF. The BF with O2-oxidized polydopamine showed the largest increase in surface energy and thermal degradation peak temperature. The greatest increase in wettability, surface roughness, and specific surface area was observed for BF modified with (NH4)2S2O8-, CuSO4-, and NaIO4-oxidized polydopamine, respectively. Due to the enhanced BF-HDPE interaction, composites made from modified BF provided better physicomechanical properties in comparison to composites prepared with unmodified BF. The composites prepared with O2-oxidized polydopamine presented the best internal adhesion, water resistance, mechanical properties, and the highest glass transition temperature. The highest heat distortion temperature and thermal degradation activation energy appeared in composites with NaIO4-oxidized polydopamine. Composites with (NH4)2S2O8-oxidized polydopamine possessed the highest melting peak temperature. Overall, O2-oxidized polydopamine was considered the most suitable for compatibilizing composites BF/HDPE.