Insights into biomacromolecule-based alcogels: A review on their synthesis, characteristics and applications

Alcogels constitute a diverse group of gels, of which the dispersing medium consists predominantly of an alcohol or a combination of alcohols and other solvent molecules. Although being investigated for a long time, alcogels have experienced an enormous increase in interest during the past decade in an effort to optimize their functionality for new applications in foods, cosmetics and pharmaceuticals. In this review, recent progress and developments on biomacromolecule-based alcogels have been summarized on many key topics, including their synthesis strategies, characteristic features and promising applications. Topics of guidelines in the perspectives of appropriate synthesis strategies, impacts of alcohols and gelators on the gel properties, especially the concentration effects, are discussed to present a broader outlook. Despite the understanding of alcogels have been evolving with ever-expanding database of structure-functionality relationships in the last decade, significant scientific challenges have emerged still in elucidating the sol-gel transition alcohols’ complex solvent chemistry along with their key roles in interrupting the hydration and intermolecular association of macromolecules, the structure formation and evolution across time and length scales. Throughout, a concise overview of proposed mechanisms is provided, future research areas and developments are envisaged as well.