The crystal structure of Valonia cellulose Iβ is determined by X-ray fiber diffraction analysis. A careful reanalysis of two existing X-ray diffraction data sets for Valonia cellulose I leads to a consistent, definitive structure of the β-phase. The results resolve ambiguities in existing X-ray analyses between “parallel up” and “parallel down” packing of the cellulose sheets in native Valonia cellulose. The molecular and sheet structures are essentially identical to those previously determined, but these results define precisely the packing of the sheets. The sheet packing is discussed in terms of the energy and density of the crystal structure. The structure of the β-phase has specific implications for the packing of the α-phase of Valonia cellulose I.

Electroactive polymers (EAPs), a new class of materials, have the potential to be used for applications like biosensors, environmentally sensitive membranes, artificial muscles, actuators, corrosion protection, electronic shielding, visual displays, solar materials, and components in high-energy batteries. The commercialization of synthetic EAPs, however, has so far been severely limited. Biological polymers offer a degree of functionality not available in most synthetic EAPs. Carbohydrate polymers are produced with great frequency in nature. Starch, cellulose, and chitin are some of the most abundant natural polymers on earth. Biopolymers are a renewable resource and have a wide range of uses in nature, functioning as energy storage, transport, signaling, and structural components. In general, electroactive materials with polysaccharide matrices reach conductance levels comparable with synthetic ion-conducting EAPs. This review gives a brief history of EAPs, including terminology, describes evaluation methods, and reports on the current progress of incorporating polysaccharides as matrices for doped, blended, and grafted electroactive materials.

A pectin and poly(lactic acid) (PLA) composite was compounded by extrusion. A model antimicrobial polypeptide, nisin, was loaded into the composite by diffusion. The incorporation of pectin into PLA resulted in a heterogeneous biphasic structure, as revealed by scanning electronic microscopy, confocal laser microscopy, and fracture-acoustic emission. The incorporation of pectin also created a rough and cragged surface, which was hydrophilic and facilitated the access and absorption of nisin. The nisin-loaded composite suppressed Lactobacillus plantarum growth, as indicated by agar diffusion and liquid-phase culture tests. The incorporation of pectin at the concentration of 20% of the total mass did not alter the Young's modulus of the film from that of the pure PLA. The composite materials were able to retain their tensile strength, flexibility, and toughness to an extent that satisfied the requirements for packaging materials. Results from this research indicate the potential of pectin/PLA composites for applications in antimicrobial packaging.