Projecting a more eco-sustainable future is a task that inevitably relies on the research and development of new materials with lower environmental impact yet no drawbacks in their applicative performances. In the field of polymer science, a precious source of raw materials is undoubtably represented by nature itself, providing a rich choice of biopolymers that may, at least partially, replace their synthetic counterparts. In this perspective, we have developed and studied different biocomposite hydrogels based on Poly(vinil-alcohol) (PVA) and rice starch obtained through a freeze-thawing method, with water as the only used solvent. Given the lack of knowledge about such systems and the potential of their applications, we provided an extended characterization of the hydrogels from a rheological, structural and physicochemical point of view. To better understand their formation mechanism and the features that derive from it, we then focused on the structural role played in the PVA-biocomposite systems by the two polymeric components of starch, amylose and amylopectin, following the phase separation dynamics of pre-gel solutions in real time by means of confocal laser scanning microscopy(CLSM). The hydrogels obtained from binary(PVA/amylose and PVA/amylopectin) and ternary(PVA/amylose/amylopectin) solutions were subjected to characterization by means of CLSM, SEM(Scanning Electron Microscopy),SAXS (Small Angle X-Ray Scattering), FT-IR(Fourier-Transform Infrared spectroscopy), DSC(Differential Scanning Calorimetry) and oscillatory rheometry. The obtained results have underlined interesting relations between the PVA to biopolymers ratio and the final structures and propertis of the hydrogels. We believe that this knowledge could represent a strong base to develop ad-hoc materials with tailorable and predictable features.

Designing green poly(vyinil-alcohol)/starch cryogels: A focus on the amylose/amylopectin structural role

ACS Fall 2021

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