Polymer paperDerivatization of cellulose in lithium chloride and N-N-dimethylacetamide solutions
Abstract
The derivatization of cellulose in mixtures of lithium chloride and N,N-dimethylacetamide (LiCl/DMAc) is described. A wide range of cellulose derivatives, including cellulose esters, carbamates, sulphonates and ethers, have been synthesized in homogeneous solution using the LiCl/DMAc solvent. In most cases, a high degree of substitution was achieved, and the degree of substitution could be controlled accurately. Compared to current heterogeneous synthesis of cellulose derivatives, reactions conducted in homogeneous solutions of LiCl/DMAc have many advantages: (1) reactions may be conducted at moderate temperatures; (2) less reagent is required; (3) less degradation of the cellulose occurs; and (4) substitution is uniformly controllable.
References (21)
- C.L. McCormick et al.
- A.J. Stamm
Wood and Cellulose Science
(1964) - H. Phillip et al.
Chemtech
(1977) - A.F. Turbak et al.
Chemtech
(1980) - S.M. Hudson et al.
J. Macromol. Sci.
(1980) - D.C. Johnson
- C.L. McCormick et al.
J. Polym. Sci., Polym. Lett. Edn.
(1979) - C.L. McCormick et al.
- McCormick, C. L. US Patent 4 278 790,...
- C.L. McCormick et al.
Polym. Prepr. Am. Chem. Soc. Div. Polym. Chem.
(1983)
Cited by (170)
Xylan cinnamoylation for reinforcing poly (butylene adipate-co-terephthalate): Molecule design and interaction optimization
2024, Carbohydrate PolymersPBAT composites with biomass fillers have gained considerable attention as alternatives to non-biodegradable plastics. This work employed xylan derivatives as fillers for PBAT composites. Xylan was modified by introducing cinnamoyl side groups which limit the hydrogen bonding and construct π-π stacking interactions with PBAT chains. The resultant xylan cinnamates (XCi) show degree of substitution (DS) of 0.55–1.89, glass-transition temperatures (Tg) of 146.5–175.0 °C and increased hydrophobicity, which can be simply controlled by varying the molar ratio of reactants. NMR results demonstrate that the C3-OH of xylopyranosyl unit is more accessible to cinnamoylation. XCi fillers (30–50 wt%) were incorporated into PBAT through melt compounding. The filler with a DS of 0.97 exhibited the optimal reinforcing effect, showing superior tensile strength (19.4 MPa) and elongation at break (330.9 %) at a high filling content (40 wt%), which is even beyond the neat PBAT. SEM and molecular dynamics simulation suggest improved compatibility and strengthened molecular interaction between XCi and PBAT, which explains the suppressed melting/crystallization behavior, the substantial increase in Tg (−34.5 → −1.8 °C) and the superior mechanical properties of the composites. This research provides valuable insights into the preparation of high-performance composites by designing the molecular architecture of xylan and optimizing the associated interactions.
Plasticizer Design Strategies Enabling Advanced Applications of Cellulose Acetate
2023, European Polymer JournalPlasticized cellulose acetate (CA) is one of the most applied bio-based polymers due to its structural properties and easy processing. Plasticizers are added to CA to increase workability, prevent degradation under processing conditions and ensure thermo-mechanical properties suitable for the intended final application. Moreover, inexpensive and non-toxic solvents enable its processing into fibers, films, and solid blocks. However, when incorporated in the polymer matrix, plasticizers are prone to migration. CA products can suffer embrittlement, cracking, warping, or discoloration during their life cycle, affecting the material’s integrity and durability. The design of new plasticizers compatible with the polymer at high concentrations, tailored to be effective in lowering the glass transition temperature, and with a low tendency to migration could considerably reduce material degradation over time.
This review offers a perspective on the current plasticizers and comprehensively depicts the plasticization mechanisms in CA for internal and external plasticization. Understanding the plasticization mechanisms paves the way to identify a rationale for designing new plasticizers for this polymer.
Probing surface properties of lactic acid bacteria - Comparative modification by anhydride and aldehyde grafting
2023, Surfaces and InterfacesSurface of Lactobacillus crispatus DSM 20584 (LBC) and Lactobacillus rhamnosus GG (LGG) from stationary and exponential phase were chemically modified using hexanoic anhydride (HA) and octanal via grafting hydrophobic moieties onto the bacterial surface hydroxyl and amine groups. The physicochemical properties of the bacteria were measured using a range of surface-sensitive methods including x-ray photoelectron spectroscopy (XPS), zeta potential measurement, contact angle measurement (CAM) and microbial adhesion to solvents (MATS). Before modification, the surface of two strains was distinctly different, where LBC was covered by hydrophobic surface-layer proteins (SLPs) while LGG was hydrophilic with the rich presence of polysaccharides. Surface hydrophilic polymers rendered steric hindrance of LGG against autoaggregation, whereas LBC lacking polysaccharides showed strong autoaggregation. After HA and octanal modifications, the intrinsic surface differences between two strains were reduced according to the Principal Component Analysis (PCA). The enhancement of hydrophobicity by HA and octanal was most likely derived from the lowered Lewis acid-base characters via elimination of hydroxyl and amine groups. Chemical modification using the two treatments can be a useful tool to tune the surface of lactic acid bacteria, which might be further applied to other microorganisms, enabling applications such as altered bacterial adhesive behaviors and biofilm formation.
Hemicellulose: Structure, chemical modification, and application
2023, Progress in Polymer ScienceLignocellulose has been extensively researched over the past decades in response to the growing global significance of renewable resources and environment-friendly materials. Hemicellulose is a large family of polysaccharides present in the primary and secondary cell walls of all land plants, fresh-water plants, and some seaweeds. It has gained significant attention in the development of hemicellulose-based functional polymeric materials owing to its distinct features such as environment-friendliness, renewability, and biodegradability. Recent studies have focused on the isolation, structural characterization, and chemical modification of hemicellulose and the preparation of hemicellulose-based materials. This review, comprehensively elaborates the preparation of hemicellulose-based functional polymeric materials via chemical modification, including the structures and properties of hemicellulose; design strategies for harnessing hemicellulose; and various forms of hemicellulose-based functional polymeric materials such as nanoparticles, films and coatings, hydrogels and aerogels, carbon quantum dots, porous carbons and catalysts. This review provides an update on hemicellulose-based functional materials, with a focus on their controlled-release, adsorption, biosensing, packaging, catalytic conversion, and electrode applications. Future perspectives on challenges and opportunities in the research field of hemicellulose are briefly highlighted.
Synthesis of paramylon ester-graft-PLA copolymers and its two-step enzymatic degradation by proteinase K and β-1,3-glucanase
2022, Polymer Degradation and StabilityParamylon ester-graft-poly(lactic acid) (PLA) copolymers were synthesized by the ring opening polymerization of l-lactide with paramylon acetate (PaAc) samples having an acetate degree of substitution (DS) from 0.5 to 2.2 (PaAc-g-PLA) or paramylon propionate (PaPr) samples with a propionate DS of 1.6 or 2.0 (PaPr-g-PLA). These copolymers exhibited thermoplasticity and some formed self-supporting melt-pressed films. Analyses of annealed films using differential scanning calorimetry showed that their thermal properties varied with the PLA DS. The enzymatic degradation behaviors of the neat paramylon as well as the PaAc and PaPr were investigated by treating these materials with β-1,3-glucanase followed by spectrometric analysis of the glucose levels in the buffer solutions, prior to the investigation of the copolymers. The data showed that 9 wt% glucose was obtained from the neat paramylon after 7 d and that the PaAc and PaPr were also degraded by β-1,3-glucanase. The concentration of liberated glucose was also found to decrease as the DS increased. Two-step enzymatic degradation tests were subsequently carried out with PaAc-g-PLA and PaPr-g-PLA specimens. In the first step, proteinase K was applied to degrade the PLA side-chains and high performance liquid chromatography (HPLC) was used to assess the release of lactic acid. Both HPLC and nuclear magnetic resonance (NMR) analyses established that the PLA side-chains of both the PaAc-g-PLA and PaPr-g-PLA specimens were successfully degraded. In the second step, β-1,3-glucanase was employed to decompose the remaining paramylon ester backbones. Monitoring the release of glucose showed that these backbones were successfully degraded in trials using the PaAc0.5-g-PLA and PaAc1.0-g-PLAs after 7 d These results confirmed that both copolymers could be broken down via this two-step enzymatic treatment, and that degradation by β-1,3-glucanase was dependent on the DS of the paramylon ester backbone. The results of this work show that PaAc1.0-g-PLA is a plastic material capable of thermal processing and is also completely biodegradable.
Conformational and rheological properties of bacterial cellulose sulfate
2021, International Journal of Biological MacromoleculesIn this study, a water-soluble bacterial cellulose sulfate (BCS) was prepared with sulfur trioxide pyridine complex (SO3· Py) in a lithium chloride (LiCl)/dimethylacetamide (DMAc) homogeneous solution system using bacterial cellulose (BC). The structural study showed that the value for the degrees of substitution of BCS was 1.23. After modification, the C-6 hydroxyl group of BC was completely substituted and the C-2 and C-3 hydroxyl groups were partially substituted. In an aqueous solution, the BCS existed as a linear polymer with irregular coil conformation, which was consistent with the findings observed using atomic force microscopy. The steady-state shear flow and dynamic viscoelasticity were systematically determined over a range of BCS concentrations (1 %–4 %, w/v) and temperature (5 °C–50 °C). Steady-state flow experiments revealed that BCS exhibited shear thinning behavior, which increased with an increase in concentration and a decrease in temperature. These observations were quantitatively demonstrated using the cross model. Moreover, based on the dynamical viscoelastic properties, we confirmed that BCS was a temperature-sensitive and weak elastic gel, which was somewhere between a dilute solution and an elastic gel. Therefore, considering the special synthetic strategy and rheological behavior, BCS might be used as a renewable material in the field of biological tissue engineering, especially in the manufacture of injectable hydrogels, cell scaffolds, and as a drug carrier.