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Cellulose-based biocompatible, tunable and injectable hydrogels embedded with pH-responsive diblock copolymer micelles were constructed to achieve localized drug delivery with prolonged, stimuli-driven and slow-release function. First, we prepared two types of modified carboxymethyl cellulose (CMC) including hydrazide-modified carboxymethyl cellulose (CMC-NH2) and oxidized carboxymethyl cellulose (CMC-CHO) with varying degrees of oxidation. Then, pH-responsive poly (ethylene oxide)-block-poly (2-(diisopropylamino) ethyl methacrylate) (PEO-b-PDPA) copolymers as micelle cores to carry hydrophobic substances were also synthesized through atom transfer radical polymerization (ATRP). An injectable hydrogel composite system was finally obtained by mixing CMC-NH2 and CMC-CHO polymer suspensions containing PEO-b-PDPA copolymer micelles through a Schiff base reaction. This newly-synthesized, tunable, cellulose-based double barrier system exhibits a pH-triggered, prolonged, and slow-release profile based on the release test using both Nile Red dye and doxorubicin. The hydrogel system also exhibited comparable storage moduli and tunable degradation properties.

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Polyurethane chemistry can yield diverse sets of polymeric materials exhibiting a wide range of properties for various applications and market segments. Utilizing lignin as a polyol presents an opportunity to incorporate a currently underutilized renewable aromatic polymer into these products. In this work, we will review the current state of technology for utilizing lignin as a polyol replacement in different polyurethane products. This will include a discussion of lignin structure, diversity, and modification during chemical pulping and cellulosic biofuels processes, approaches for lignin extraction, recovery, fractionation, and modification/functionalization. We will discuss the potential of incorporation of lignins into polyurethane products that include rigid and flexible foams, adhesives, coatings, and elastomers. Finally, we will discuss challenges in incorporating lignin in polyurethane formulations, potential solutions and approaches that have been taken to resolve those issues.

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Chitosan is an abundant and natural polymer derived from chitin, which presents a wide variety of properties, including antimicrobial activity. The raising of antibiotic resistant bacteria has increased the interest in finding alternatives to traditional antibiotics. Many studies have assessed the antimicrobial activity of chitosan itself, but a few have performed comparisons among different chitosan nanoparticle synthesis, which will be of particular interest for further applications. In this study, the effects of two types of cross-linking agents, sodium sulfate vs. tripolyphosphate, along with molecular weight (Mw) of chitosan, low vs. high Mw, and different sonication treatments, time and power, were assessed to determine the optimal conditions to enhance antimicrobial activity against bacterial pathogens. Physiochemical characteristics of the engineered chitosan nanoparticles were determined. It was observed that 20 min sonication time, low Mw of chitosan, Sodium sulfate as cross-linker, and particle size smaller than <300 nm, showed the greatest antimicrobial activity. Chitosan nanoparticles generated at this condition completely killed pathogenic E. coli O157:H7 without raising resistant bacteria, providing great insights into potential use as alternative antimicrobial agents.

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Biocomposites with tunable properties were successfully prepared through ionic assembly between anionic carboxymethyl cellulose (CMC) and cationic copolymers (quaternized poly(l-lactide)-block-poly N,N-dimethylamino-2-ethyl methacrylate) (PLA-b-PDMAEMA). The quaternized PDMAEMA segment not only works as a compatibilizer between hydrophilic CMC and hydrophobic PLA, but also acts as a lubricant between these two rigid biopolymers. The (1)H NMR (nuclear magnetic resonance) spectra demonstrated successful synthesis of PLA-b-PDMAEMA with controlled molecular weight of PDMAEMA segment. The results from scanning electronic microscopy (SEM) and Fourier transform infrared spectrometry (FTIR) verified the interaction between quaternized copolymer micelles and anionic CMC networks. The resultant biocomposite could form a transparent and uniform film after casting. Both storage moduli and maximum degradation temperature of PLA/CMC composites were increased with the reduction of molecular weight of PDMAEMA segments. It suggests that the properties of biocomposite materials can be tailored by adjusting the chain length of inclusive PDMAEMA segment.

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