Green synthesis of a novel biodegradable copolymer base on cellulose and poly(p-dioxanone) in ionic liquid

In situ synthesis of gold nanoparticles on pseudo-paper films as flexible SERS substrate for sensitive detection of surface organic residues

Surface enhanced Raman scattering (SERS) substrates that can be attached to rough, irregular surfaces and directly collect samples is especially useful for the detection of surface organic residues. Herein, novel AuNPs-pseudo-paper films (APPFs) with uniform structure, flexible properties and wicking capabilities were first fabricated and used as SERS substrate for the sensitive detection of surface pesticides residues. Gold nanoparticles (AuNPs) were in situ synthesized on pseudo-paper films (PPFs) by iterative seeding method to create lots of "hot-spots", accordingly exhibiting high SERS activity (SERS enhancement factor of 3.02 × 10⁶). By virtue of polyethylenimine (PEI) grafted onto the dissolved microcrystalline cellulose (MCC), AuCl₄^- and AuNPs can firmly be bonded to the surfaces of PPFs. The prepared APPFs show high reproducibility (relative standard deviation of 6.13%), which is attributed to the uniform surface of the films. The fabricated APPFs SERS substrate allows rapid detection of surface pesticides residues by a facile "swabbing-measure" detection mode avoiding tedious and time-consuming sampling and separation processes. Based on their inherent SERS spectra, thiram, parathion methyl, and malachite green (MG) can be simultaneously detected on apple peel, which demonstrates the potential applicability of this developed protocol for surface organic residues analysis in agriculture and food security.

Isothermal Crystallization and Rheology Properties of Isotactic Polypropylene/Bacterial Cellulose Composite

Bacterial cellulose (BC) is a new kind of cellulose with great potential in enhancing preparation of isotactic Polypropylene (iPP) composites, which have been found with excellent performance. However, the interface compatibility between BC and iPP is poor. In this study, iPP/BC composites were prepared by solution mixing. Esterification modified BC (CO) and Maleic anhydride grafted polypropylene (MAPP) added as a compatibilizer was both used to improve the interfacial compatibility of the iPP/BC composites. The rheology and isothermal crystallization behavior of the composites was tested and discussed. The result shows that the complex viscosity and storage modulus of the composite significantly increase in the rule iPP, iPP/BC2, iPP/CO2, and M-iPP/BC3, which indicates that the compatibility of the composite increases as this rule. According to the isothermal crystallization kinetics result, the crystal growth mode of iPP was not affected by the addition of BC and the interfacial compatibility. The spherulite growth rate of the iPP/BC composite increases with increasing crystallization temperature. Especially, the value decreases as the same rule with the complex viscosity and storage modulus of the composite at the same isothermal crystallization temperature. These results suggest that the interface compatibility of iPP/BC composites is greatly improved and the interface compatibility of the M-iPP/BC3 is better than the iPP/CO2.

Enzymatic catalysis for sustainable production of high omega-3 triglyceride oil using imidazolium-based ionic liquids

Two different fish oil preparations, namely triglycerides and ethyl esters containing, respectively, 30.02% and 74.38% of omega-3 fatty acids, were employed as the substrates for transesterification. Catalyzed by immobilized lipase using imidazolium-based ionic liquid systems, the total content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the resulting triglyceride reached 63.60% when 4% hydrophobic ionic liquid was used, which was 11.74% higher than that of the triglyceride produced in a solvent-free reaction system. The activation energy of the product (triglyceride-type fish oil) was 173.64 KJ mol-1, which was not significantly different from that of the commercial ethyl ester-type fish oil, so were the other thermal oxidative kinetic parameters. The kinetic parameters depicting the thermal and oxidative stability of the fish oil product provide the basis for industrial processing, storage, and applications.

Organic Catalysis for Ring-Opening Graft Polymerization of p-Dioxanone with Xylan in Ionic liquid

Recently, organic catalysis has become a powerful alternative to the use of more traditional metal-based catalysts. In this study, 4-dimethylaminopyridine (DMAP), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were applied to mediate the ring-opening graft polymerization (ROGP) of p-dioxanone (PDO) with xylan-based hemicelluloses in ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). Excellent control of the molar ratio of the catalyst to anhydroxylose units (AXU) in xylan was found for a good tuning of the weight percent gain (WPG) of xylan-graft-poly(p-dioxanone) (xylan-g-PPDO) copolymers. As a result, the maximum WPG of xylan-g-PPDO copolymers was 431.07% (DMAP/AXU of 2/1), 316.72% (DBU/AXU of 0.2/1), and 323.15% (TBD/AXU of 0.2/1), respectively. The structure of xylan-g-PPDO copolymers was characterized with FT-IR and NMR. The thermal properties of copolymers were investigated using thermogravimetric analysis (TGA/DTG) and differential scanning calorimetry (DSC), and a significant difference was observed regarding the transition temperature (Tg), melting temperature (Tm), and crystallization temperature (Tc).

Preparation of Esterified Bacterial Cellulose for Improved Mechanical Properties and the Microstructure of Isotactic Polypropylene/Bacterial Cellulose Composites

Bacterial cellulose (BC) has great potential to be used as a new filler to reinforce isotactic polypropylene (iPP) due to its high crystallinity, biodegradability, and efficient mechanical properties. In this study, esterification was used to modify BC, which improved the surface compatibility of the iPP and BC. The results indicated that the cellulose octoate (CO) changed the surface properties from hydrophilic to lipophilic. Compared to the pure iPP, the tensile strength, charpy notched impact strength, and tensile modulus of the iPP/BC composites increased by 9.9%, 7.77%, and 15.64%, respectively. However, the addition of CO reinforced the iPP/CO composites. The tensile strength, charpy notched impact strength, and tensile modulus of the iPP/CO composites increased by 14.23%, 14.08%, and 17.82% compared to the pure iPP. However, the elongation at break of both the composites is decreased. The SEM photographs and particle size distribution of the composites showed improvements when the change of polarity of the BC surface, interface compatibility, and dispersion of iPP improved.

Novel phosphorus-containing halogen-free ionic liquids: effect of sulfonate anion size on physical properties, biocompatibility, and flame retardancy

Phosphorus-containing sulfonate ILs with different anions size present different thermal stability, solubility, viscosity, melting points, and cytotoxicity. They show flame retardant effect for PA6 via accelerating decomposition of matrix.

Preparation of modified cotton cellulose in ionic liquid and its adsorption of Cu(ii) and Ni(ii) from aqueous solutions

A series of novel cotton cellulose-graft-polycaprolactone copolymers with different grafting contents were successfully prepared via ring-opening polymerization (ROP) in an ionic liquid 1-N-butyl-3-methylimidazolium chloride ([Bmim]Cl).

Self-assembly and paclitaxel loading capacity of cellulose-graft-poly(lactide) nanomicelles

A series of amiphiphilic cellulose-based graft copolymers (MCC-g-PLA) with various molecular factors were synthesized in ionic liquid BmimCl and characterized by FT-IR, (1)H NMR, (13)C NMR, XRD, and TGA. Their solubility in a variety of solvents was compared. The prepared MCC-g-PLA copolymers can self-assemble into spherical nanomicelles (10-50 nm) in aqueous solution. The self-assembly behaviors of the MCC-g-PLA copolymers were systematically investigated by fluorescence probe. Furthermore, the hydrophobic antitumor drug paclitaxel (PTX) was successfully encapsulated into the MCC-g-PLA micelles. The drug encapsulation efficiency and loading content were found to be as high as 89.30% (w/w) and 4.97%, respectively. Results in this study not only suggest a promising cellulose-based antitumor drug carrier but also provide information for property-directed synthesis of the cellulose graft PLA copolymers.

Homogeneous Grafting of Bagasse Cellulose in Ionic Liquid

A new cellulose graft copolymer was synthesized by the homogeneous graft polymerization in ionic liquid. The methyl methacrylate was successfully grafted onto the bagasse cellulose in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) as a homogenous media. The obtained copolymer was characterized by Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscope (SEM). The results of thermal analysis curves exhibited two separated pyrolysis with cellulose and the grafted pMMA. Moreover, the homogenous reaction media applied can be carried out in completely recycled ionic liquid, and the modified cellulose has a potential value for oil absorbent.