Polysaccharides and proteins are abundantly found in nature and are highly recommended for developing eco-friendly materials due to their special properties (biodegradability, biocompatibility, non-toxicity, low cost, etc.). However, they sometimes fail to meet specific requirements due to poor mechanical and physical properties. Poly(vinyl alcohol) (PVA) is one of the promising synthetic polymers with superior properties that can be blended with natural polymers for obtaining novel biomaterials with improved performances. This review addresses recent advance in PVA/polysaccharides and PVA/proteins biocomposites design and fabrication, mainly for the past two decades.

Rheological behaviour of poly(vinyl alcohol) (PVA) aqueous systems was systematically investigated at 30 °C for different concentrations, molecular weights and hydrolysis degrees. The viscosity of very dilute polymer solutions was studied by means of viscometry, while the concentrated solutions were analyzed by steady shear flow measurements. The limit between the entangled and non-entangled states of PVA aqueous solutions was determined as the crossover of two scaling laws describing the dependence of specific viscosity as a function of coil overlap parameter, c[η]. Then, physical gels with good elastic properties were prepared in situ by freezing/thawing/ageing (200 min per cycle) of entangled PVA solutions. The influence of each stage of the applied cryogenic treatment on the gel formation and elastic properties of the final network was followed by means of dynamic rheological measurements at low strain, in the linear domain of viscoelasticity. It was shown that the gel properties largely depend on the initial state of PVA solutions, as described by the c[η] value, and on the degree of hydrolysis, as well as on the thermal history, i.e., the number of cryogenic cycles, thawing rate, and ageing step. For a given coil overlap parameter, the elastic modulus of cryogels tends to a limiting value, which can be reached faster by adding an ageing sequence to the classical freezing/thawing cryogenic cycles. This maximum value of the elastic modulus increases with increasing the coil overlap value of the initial solution.