Strong nanocomposite reinforcement effects in poly(vinyl alcohol) with melanin nanoparticles

Poly(vinyl alcohol)/melanin nanocomposites with improved tensile strength, Young's modulus and heat distortion temperature (HDT) were prepared by using simple aqueous solution mixing. When incorporated into PVA with low content (0.5-2 wt%), melanin nanoparticles dramatically enhanced the mechanical properties of PVA. With addition of 2 wt% melanin, the nanocomposites exhibited a tensile strength (sigma) of 155 MPa and a Young's modulus (E) of 2.95 GPa, which were much higher than these of neat PVA. HDT was enhanced from 56.5 degrees C to 100 degrees C. TEM indicated that melanin nanoparticles were uniformly dispersed in PVA without aggregation. The strong hydrogen bonding between the -OH (or -NH-) of melanin and -OH of PVA confirmed by FTIR, which played a key factor to prevent the aggregation of nanoparticles in PVA matrix and made a contribution to the high performance of PVA.