Bacterial Cellulose Aerogels: From Lightweight Dietary Food to Functional Materials

Abstract

Aerogels are highly porous, extremely lightweight materials that have a huge application potential. Following their inorganic and organic predecessors, such as the “famous” silica-based materials, aerogels from renewables, in particular cellulose, are sometimes regarded as the third, “young” generation of aerogels, and research in this field has literally undergone a boom at the turn of the millennium. This book chapter introduces a subclass of cellulosic aerogels: Bacterial cellulose (BC) aerogels. Compared to mechanically, chemically or enzymatically processed plant celluloses, BC features some outstanding properties, such as high purity, high molecular weight and high gelation that render this natural source an excellent candidate for biomedical applications. Following a brief introduction of the natural resource bacterial cellulose, the chapter describes in detail the preparation of BC aerogels and comprehensively discusses their properties, in particular their pore features and their response to mechanical stress. Furthermore, the loading of BC aerogels with bioactive compounds is reported, revealing the potential for controlled release applications. The preparation of interpenetrating networks that consists of BC and a second polymer, such as cellulose acetate, is shown to have a strong mechanical reinforcement effect. Based on their recent work, the authors finally propose a new definition that might help to describe “aerogels” more precisely.