Wood-Derived Polymers from Olefin-Functionalized Lignin and Ethyl Cellulose via Thiol-Ene Click Chemistry

Lignin and cellulose derivatives have vast potential to be applied in polymer materials. The preparation of cellulose and lignin derivatives through esterification modification is an important method to endow cellulose and lignin with good reactivity, processability and functionality. In this study, ethyl cellulose and lignin are modified via esterification to prepare olefin-functionalized ethyl cellulose and lignin, which are further used to prepare cellulose and lignin cross-linker polymers via thiol-ene click chemistry. The results show that the olefin group concentration in olefin-functionalized ethyl cellulose and lignin reached 2.8096 mmol/g and 3.7000 mmol/g. The tensile stress at break of the cellulose cross-linked polymers reached 23.59 MPa. The gradual enhancement in mechanical properties is positively correlated with the olefin group concentration. The existence of ester groups in the cross-linked polymers and degradation products makes them more thermally stable. In addition, the microstructure and pyrolysis gas composition are also investigated in this paper. This research is of vast significance to the chemical modification and practical application of lignin and cellulose.

Preparation of Biomass-Based Ester End-Capped Hyperbranched Poly(ether)s via Facile One-Pot Reaction and Their Performance as Non-Toxic Plasticizers

The aim of this study was to develop a facile one-pot reaction for the synthesis of biomass-based hyperbranched poly(ether)s end-capped as acetate esters (BHE) for use as a sustainable, safe and feasible plasticizer for flexible poly(vinyl chloride) (PVC) materials. BHE is completely miscible with PVC but shows weaker plasticizing effect than dioctyl phthalate (DOP) (EΔTg value of BHE reaches 64.8%). PVC plasticized with BHE displays greater thermal stability than that of PVC or PVC plasticized with DOP materials. BHE improves the thermal stability and flexibility of PVC materials. As a plasticizer, BHE displays lower solvent extractability and greater volatilization resistance than DOP. Acute oral toxicity indicates that BHE has toxic doses of 5 g/kg, suggesting that BHE is non-toxic.

Role of the Oxethyl Unit in the Structure of Vegetable Oil-Based Plasticizer for PVC: An Efficient Strategy to Enhance Compatibility and Plasticization

Developing vegetable oil-derived primary plasticizers for poly(vinyl chloride) (PVC) is still a challenge because of their insufficient compatibility. As described in this work, we report the synthesis of plasticizers through the esterification of polyethylene glycol methyl ether and dimer acid, in which dimer acid is renewable material prepared via a two-step reaction (1) the hydrolysis of fatty acids from soybean oil at 70 °C and (2) subsequent Diels-Alder reaction at 250 °C. The resulting plasticizers, dimer acid-derived polyethylene glycol methyl ether esters (DA-2n, 2n = 2, 4, 6 or 8 referring to the number of oxethyl units per molecule), were blended with PVC. It was found that the tensile properties, transparency, and thermal stability of plasticized PVC (PVC-DA-2n) increased significantly with an increase in the number of oxyethyl units. Fourier-transform infrared spectroscopy analysis revealed that its good compatibility can be attributed to the strong interaction between oxyethyl units and PVC. As the number of the oxyethyl units of plasticizer increased, the glass transition temperature (T_g) of the corresponding plasticized PVC samples decreased from 62.3 (PVC-DA-2) to 35.4 °C (PVC-DA-8). Owing to the excellent plasticization of DA-8, the performances of PVC-DA-8 were comparable or better than that of the PVC plasticized using commercial dioctyl terephthalate (DOTP). The simple but efficient method of this study provides a new avenue for the preparation of vegetable oil-based plasticizers for PVC.

Synthesis and properties of castor oil based plasticizers

A series of environment-friendly plasticizers has been synthesized from castor oil through a mild esterification/epoxidation reaction. The modified epoxy acetylated castor oil (EACO) can plastify poly(vinyl chloride) (PVC) efficiently, even better than the commercial plasticizers dioctyl terephthalate (DOTP) and epoxidized soybean oil (ESO), in terms of in tensile strength, migration stability, solvent extraction stability and thermal stability. Specifically, the tensile strength and elongation at break of a PVC sample plastified by epoxy acetylated castor oil (EACO) were 18.5 and 10.0% higher than that of DOTP, and 13.9 and 23.8% higher than that of ESO, respectively. Volatility, migration, solvent extraction and thermal stability tests indicated that the presence of carbon-carbon double bonds and hydroxy groups reduce the compatibility of a plasticizer with PVC while the presence of epoxy groups and ester bonds can improve the plasticizing effect of the plasticizer on PVC. In addition, alkyl groups can improve the plasticizing effect on PVC while benzene rings increase the rigidity of the PVC. The design strategy based on castor oil highlights a sustainable avenue for preparing cost-effective and high-efficiency plasticizers.

Fabrication of graphite/MgO-reinforced poly(vinyl chloride) composites by mechanical activation with enhanced thermal properties

Fabrication of graphite/MgO reinforced poly(vinyl chloride) composites with enhanced thermal properties by mechanical activation.

Eliminating the Need for Biocidal Agents in Anti-Biofouling Polymers by Applying Grafted Nanosilica Instead

A nondestructive one-step approach was applied for grafting biocide-free monodispersed silica nanoparticles (SNPs) with a diameter of 30 ± 10 nm on polystyrene, polyethylene, and polyvinyl chloride surfaces. The prepared surfaces were comprehensively characterized using spectroscopic (Fourier transform infrared attenuated total reflection, ultraviolet-visible, and X-ray photoelectron spectroscopy) and microscopic (high-resolution scanning electron microscopy and atomic force microscopy) methods. The modified polymers were found to maintain their original mechanical and physical properties, while their nanoroughness on the other hand had risen by 1.6-2.7 times because of SNP grafting. The SNP-grafted surfaces displayed anti-biofouling properties, resulting in a significant reduction in the attached Gram-positive Bacillus licheniformis or Gram-negative Pseudomonas aeruginosa bacteria compared to their nongrafted counterparts. Confocal laser scanning microscopy and scanning electron microscopy studies have confirmed that bacterial cells could not successfully adhere onto the SNP-grafted polymer films regardless of the polymer type, and their biofilm formation was therefore damaged. The presented facile and straightforward protocol allows eliminating the need for biocidal agents and resorts to grafted nanosilica instead. This strategy may serve as a feasible and safe platform for the development of sustainable anti-biofouling surfaces in biomedical devices; food, water, and air treatment systems; and industrial equipment.

A novel DOPO-g-KH550 modification wood fibers and its effects on the properties of composite phenolic foams

A novel 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) graft γ-amino propyl triethoxy silane (KH550) was synthesized and introduced on the surface of wood fiber. Finally DOPO-g-KH550 treated wood fiber (DKTWF) was used to prepare DKTWF composite phenolic foams (DKTWFCPF). The structures of DOPO-g- KH550 was acknowledged by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (1H-NMR). The structures of DKTWF were confirmed by FT-IR. Compared with wood fiber, the diffraction peaks’ position was basically unchanged, but the crystallinity was slightly increased and thermal stability were dramatically improved, T5% and Tmax increased by 21.9o and 36.1o respectively. But the char yield (800o) was slightly reduced. With the dosage of DKWF, there were different degrees of improvement including the mechanical properties, flame retardancy and microstructure of DKTWFCPF. Comprehensive analysis, the interfacial compatibility was significantly improved between DKTWF and phenolic resin, and the suitable content of DKTWF was 4%.

Loading an organophosphorous flame retardant into halloysite nanotubes for modifying UV-curable epoxy resin

Novel flame-resistant UV-curable epoxy (EP) composites were prepared using the organophosphorous flame retardant dimethyl methylphosphonate (DMMP) which was loaded into halloysite nanotubes (HNTs).