Promising Energetic Polymers from Nanostructured Bacterial Cellulose

Abstract

This study investigated the nitration of nanostructured bacterial cellulose (NBC). The NBC, obtained using symbiotic Medusomyces gisevii Sa-12 as the microbial producer and then freeze-dried, was nitrated herein by two methods, the first using mixed sulphuric–nitric acids (MA) and the second using concentrated nitric acid in the presence of methylene chloride (NA+MC). The synthesized samples of NBC nitrates (NBCNs) exhibited 11.77–12.27% nitrogen content, a viscosity of 1086 mPa·s or higher, 0.7–14.5% solubility in an alcohol–ester mixture, and 0.002% ash. Scanning electron microscopy showed that the nitration compacted the NBC structure, with the original reticulate pattern of the structure being preserved in full. Infrared spectroscopy for the presence of functional nitro groups at 1658–1659, 1280, 838–840, 749–751 and 693–694 cm−1 confirmed the synthesis of cellulose nitrates in particular. Thermogravimetric and differential thermal analyses showed the resultant NBCNs to have a high purity and high specific heats of decomposition of 6.94–7.08 kJ/g. The NBCN samples differ conceptually from plant-based cellulose nitrates by having a viscosity above 1086 mPa·s and a unique 3D reticulate structure that is retained during the nitration. The findings suggest that the NBCNs can be considered for use in novel high-tech materials and science-driven fields distinct from the application fields of plant-based cellulose nitrates. The NBCN sample obtained with NA+MC has the ability to generate an organogel when it is dissolved in acetone. Because of the said property, this NBCN sample can find use as a classical adhesive scaffold and an energetic gel matrix for creating promising energetic polymers.

Cellulose Nitrates-Blended Composites from Bacterial and Plant-Based Celluloses

“…The higher decomposition temperature of cellulose evidences its purity and thermal stability [44,46,59]. Therefore, the obtained findings are consistent with the data on cellulose purity outlined in Table 1 and with the other BC study results [36,60].…”

“…The top and bottom lines in Figure 3 show a conceptual difference in the structure and dimension of the bacterial cellulose (BC) and oat-hull cellulose (OHC) fibers: the former exhibits a reticulate fiber structure with a nanoscale fiber width, specifically 40-70 nm, while the latter consists mainly of flat cellulose fibers distinct in shape and dimensions: ribbon-shaped, spiral-shaped, or curved fibers with toothed edges, a fairly even shape, and a fiber width of 10-40 µm. Once nitrated, CN BC became structurally more compact while retaining the reticulate structure of the starting BC, in agreement with other studies [31,33,36]. When nitrated, the plant cellulose also retained the fiber shape of the starting cellulose; however, the CN fibers swelled and their surface became smoother.…”

“…The synthesis of CNs requires that cellulose-concomitant components be removed from plant raw materials, and these processes inflict environmental damage [21]. Research has focused on finding new energetic materials [22][23][24] with a high purity and a unique reticulate nanostructure [25,26] concerning nanocellulose [27][28][29] and, most notably, bacterial cellulose (BC) as the leader among the nanocelluloses [30][31][32], has presently reached its highest demand [33][34][35][36][37]. The broad application prospects and benefits of nanocellulose nitrate-based energetic materials were overviewed back in 2014 [38].…”

“…The initial works on the synthesis of CN from BC (CN BC) were described as early as 2006 [22] and 2010 [23]. The next wave of larger and more extensive studies on CN BC started in 2018 [24] and continues to the present [25][26][27][28][29][30][31][32][33][34][35][36][37] because CN BC has several advantages over plant-based cellulose nitrates, in particular, its high stability due to the ultrafine, high-purity, reticulate fibrous structure.…”

Simultaneous Production of Cellulose Nitrates and Bacterial Cellulose from Lignocellulose of Energy Crop

“…The possibility of producing a new CN type from bacterial cellulose (BC) has been justified alongside the use of non-woody cellulose, and prospects for using this new type have been considered [ 10 , 27 , 28 , 29 ].…”