Bacterial cellulose-based membrane-like biodegradable composites using cross-linked and noncross-linked polyvinyl alcohol

Abstract

Bacterial cellulose (BC)-based membrane-like biodegradable composites were produced by immersing wet BC pellicles in polyvinyl alcohol (PVA) solution. The BC content in the BC-PVA composites can be adjusted by varying the concentration of PVA solution. Chemical cross-linking of PVA was carried out using glutaraldehyde to increase the mechanical properties of the composites as well as to make the PVA partially to highly water insoluble. Examination by scanning electron microscopy indicated that the PVA not only penetrated the BC network, but also filled the pores within the BC pellicle. Attenuated total reflectance-Fourier transform infrared spectroscopy showed that acetal linkages could be formed in the BC-PVA composites by a cross-linking reaction. Sol-gel results indicated that cross-linking reaction increasingly made PVA insoluble in water resulting in higher gel (crosslinked fraction) content in the PVA. Wide-angle X-ray diffraction results showed decreased crystallinity in crosslinked BC and PVA, as expected. It was also found that crystal size was smaller in PVA after cross-linking. The BC-PVA composites had excellent tensile properties and cross-linking increased these properties further. Thermogravimetric analysis showed higher thermal stability for BC-PVA composites compared to PVA. The cross-linked specimens, especially the highly cross-linked ones, showed even higher thermal stability. The methods developed in this study make it possible to control the PVA content in the composites as well as the cross-linking level of PVA. These composites could be good candidates for replacing traditional non-biodegradable plastics.

A soft biomolecule actuator based on a highly functionalized bacterial cellulose nano-fiber network with carboxylic acid groups

“…29 For the CBC membrane, the first, second and third weight loss occurred at 40-120℃, 240-350℃ and 350-600 ℃, respectively. The TGA curve of BC having three weight loss steps can be assigned to: the first weight loss (40-130℃) due to water loss, the second weight loss (300-360℃) owing to the main chain decomposition and the third weight loss (360-600 ℃ ) attributed to the residual main chain decomposition.…”

“…3b, and their mechanical properties are compared in Table 1. 29 For the CBC case, the diffraction peaks displayed at 2θ = 14.58°, 17.08° and 22.71°. In the case of CBC-IL membrane, however, the value of tensile strength increased up to 44.26 MPa and it means increase by 12.4% compared with the pure CBC; in particular, the soft CBC-IL composite membrane exhibits an exceptionally superior elongation, up to 22%, which is better than that of BC and CBC membranes.…”

In Situ Produced Bacterial Cellulose Nanofiber-Based Hybrids for Nanocomposites

“…It is clear that the MFC fibers are capable of homogenously filling the pores present in the BC nanofiber network structure and, thus, eliminating many potential weak points (pores or voids) in the BC network. Earlier researchers have shown that the BC pellicles have large amounts of pores or voids that are somewhat uniformly distributed [5]. Such structures have made BC membranes suitable for ultrafiltration [1].…”

“…However, BC fibers have diameters that range between 55 and 60 nanometers and display many unique characteristics, such as high purity and high water-holding capacity [1,2]. Due to their high crystallinity, high degree of polymerization, and higher molecular orientation they also have high strength and stiffness (Young s modulus), as well as higher thermal stability compared to conventional plant-derived cellulose fibers [1,[3][4][5]. BC membranes obtained through static fermentation tend to have a highly porous structure combined with strong biocompatibility [1,[6][7][8][9] and excellent environmental biodegradability [3][4][5]10] and, importantly, their size, shape, and thickness can be easily controlled [1,11,12].…”

“…Due to their high crystallinity, high degree of polymerization, and higher molecular orientation they also have high strength and stiffness (Young s modulus), as well as higher thermal stability compared to conventional plant-derived cellulose fibers [1,[3][4][5]. BC membranes obtained through static fermentation tend to have a highly porous structure combined with strong biocompatibility [1,[6][7][8][9] and excellent environmental biodegradability [3][4][5]10] and, importantly, their size, shape, and thickness can be easily controlled [1,11,12]. BC materials in various forms have already been used in many applications including binding agents for fibers and other materials [1,13], cosmetics [2], high-quality paper [1], foods (e.g., nata-de-coco) [2], loud speaker diaphragms [13], textiles and apparel [13], artificial skin and blood vessels [14,15], nanocomposite membranes [1,3,[11][12][13], and others [16,17].…”