Synthesis and characterization of hydroxypropyl cellulose from bacterial cellulose

Bacterial cellulose produced by Acetobacter xylinum has been reacted with propyleneoxide to synthesize hydroxypropyl cellulose(HPC) under different reaction conditions while diluted by toluene. The effects of mass ratio of bacterial cellulose to propyleneoxide, dilutability of toluene, reaction temperature(T) and time(t) were investigated by series of experiments. The degree of substitution(DS), hydroxypropyl content(A) and yield(η) were compared. The optimized product exhibited cold-water solubility and hot-water gelatinization in aqueous medium. Further study was carried out with FTIR, TGA, XRD, SEM and 13C-NMR for characterization. The water/air contact angle measurement reveals that it is a good hydrophobic material with good mechanical properties.     

Synthesis and characterization of polymeric linseed oil grafted methyl methacrylate or styrene

Syntheses of wholly natural polymeric linseed oil (PLO) containing peroxide groups have been reported. Peroxidation, epoxidation and/or perepoxidation reactions of linseed oil, either under air or under oxygen flow at room temperature, resulted in polymeric peroxides, PLO-air and PLO-ofl, containing 1.3 and 3.5 wt.-% of peroxide, with molecular weights of 2 100 and 3 780 Da, respectively. PLO-air contained cross-linked film up to 46.1 wt.-% after a reaction time of 60 d, associated with a waxy, soluble part (PLO-air-s) that was isolated with chloroform extraction. PLO-ofl was obtained as a waxy, viscous liquid without any cross-linked part at the end of 24 d under visible irradiation and oxygen flow. Polymeric peroxides, PLO-air-s and PLO-ofl initiated the free radical polymerization of both methyl methacrylate (MMA) and styrene (S) to give PMMA-graft-PLO and PS-graft-PLO graft copolymers in high yields with Mw varying from 37 to 470 kDa. The polymers obtained were characterized by FT-IR, (1)H NMR, TGA, DSC and GPC techniques. Cross-linked polymers were also studied by means of swelling measurements. PMMA-graft-PLO graft copolymer film samples were also used in cell-culture studies. Fibroblast cells were well adhered and proliferated on the copolymer film surfaces, which is important in tissue engineering.     

A novel amphotropic polymer based on cellulose nanocrystals grafted with azo polymers

A novel amphotropic polymer which could exhibit liquid-crystalline behavior both in the solvent and in the heating process was synthesized through azo polymers grafting from cellulose nanocrystals (CNCs). The CNCs, prepared by acid hydrolysis of filter paper, were characterized by Atomic Force Microscopy (AFM). Poly{6-[4-(4-methoxyphenylazo)phenoxy] hexyl methacrylate}(PMMAZO), which was a liquid-crystalline polymers (LCP), was successfully to graft from CNC via Atom transfer radical polymerization (ATRP). The structure and thermal properties of the PMMAZO-grafted CNC were investigated using Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analyses (TGA). Its phase structures and transitions were studied by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The experimental results showed that the PMMAZO-grafted CNC exhibited both types of liquid crystal formation, thermotropic and lyotropic.     

Synthesis and mechanical characterisation of cellulose based textiles grafted with acrylic monomers

Grafting polymerisation of methyl methacrylate and ethyl acrylate onto linen and cotton was carried out in order to reinforce these materials, when they underwent degradation. Take into account this aim, an artificially ageing was performed onto cellulose based textiles by metaperiodate oxidation, in order to obtain degraded model samples. Carbonyl groups were introduced in the cellulose and used as photosensitive agents, allowing the formation of radical sites during the polymerisation reaction, that started by irradiating the substrate by ultraviolet light.In this paper the effectiveness of grafting polymerisation as a method for textile conservation is discussed, starting from the results obtained from several characterisations, as the grafting yields and the grafting efficacy evaluation, the DSC analysis, the FTIR spectroscopy and the SEM observations. Moreover the consolidating and the protective effects were investigated by evaluating the mechanical properties and the wetting behaviour of the grafted samples, and comparing them with the original and aged substrates. The mechanical strength of cellulose based textiles has been improved, as well as the wetting behaviour has been enhanced.     

Synthesis and characterization of (hydroxypropyl)cellulose/TiO2 nanocomposite films

A new method of synthesis of TiO₂ nanoparticles as well as preparation of the organic–inorganic hybrid nanocomposite films of (hydroxypropyl)cellulose (HPC)/TiO₂ is presented. At the first stage, the oxotitanium hydrogel phase was obtained by the mineralization of (tetra‐isopropyl)orthotitanate (TIPT) modified by the methacrylic acid (MAA) in 15 wt% solution of H₂O₂ at room temperature and subsequent annealing at the temperature of 85°C. The crystallization of the nanoparticles of TiO₂ was conducted at the oxotitanium hydrogel phase at temperatures around 120°C in the closed vessel. Nanocomposite hybrid films were prepared by the casting method from a solution of HPC and TiO₂ nanoparticles in the water. The films of nanocomposite with 10 µm thickness are transparent to visible light and have a lower glass transition temperature compared with HPC in the bulk. This shift of the glass transition is interpreted in terms of packing density of HPC in the interface of HPC nanocomposite with TiO₂. The X‐ray diffraction pattern of the nanocomposite film suggests a lower amount of mesomorphic phase of HPC in the composite compared with HPC in the bulk. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and characterization of novel biodegradable and electroactive hydrogel based on aniline oligomer and gelatin

A biodegradable electroactive hydrogel (AP-g-GA), aniline pentamer (AP) grafting gelatin (GA), is synthesized by a coupling reaction between the carboxyl group of AP and the amino side group of GA in aqueous solution. The electroactivity of the physical hydrogel is confirmed by UV-vis and CV. The hydrophobic AP changes the hydrogel's porous structure of the natural GA and the gel-time, which is confirmed by the rheological behavior of the AP-g-GA and GA. With an increase in the content of AP, the hydrogel gradually forms a porous structure, from "honeycomb" to "bamboo raft". The porous scaffolds can be crosslinked with 3.5% EDC in 90% ethanol. MTT assays show that the AP-g-GA exhibits reduced cytotoxicity compared to EM AP due to the introduction of the biocompatible GA moiety. The in vitro cell cultures suggest that the AP-g-GA#1 (with 1.9% AP) shows the best biocompatibility and cell adhesion ability.     

Composite hydrogels based on polyacrylamide and cellulose: Synthesis and functional properties

Biocompatible composite hydrogels based on polyacrylamide and reinforced with bacterial or vegetable cellulose were synthesized. In the mechanical characteristics and water content, these hydrogels are similar to knee joint cartilages with average rigidity level. The structure and chemical composition of the hydrogels after their residence for 45 days in laboratory animal joints were studied by scanning electron microscopy and energydispersive X-ray microanalysis. Prolonged contact of the hydrogels with bones results in formation of calcium phosphate spherulites similar in composition to hydroxyapatite.     

Synthesis and characterization of novel amino cellulose esters

The homogeneous conversion of cellulose dissolved in N-methyl-2-pyrrolidone/LiCl and 1-N-butyl-3-methylimidazolium chloride with N-methyl-2-pyrrolidone, ε-caprolactam, N-methyl-ε-caprolactam, and N-methyl-2-piperidone in the presence of p-toluenesulphonic acid chloride was studied. Depending on the reaction conditions, novel cellulose esters with degree of substitution (DS) values ranging from 0.12 to 1.17 could be prepared. The structure of the amino group containing cellulose esters was elucidated by elemental analysis, FTIR- and NMR spectroscopy. NMR spectroscopy revealed an almost complete esterification of position 6 of the anhydroglucose unit at DS of 1. The conversion can be conducted between room temperature and 40 °C, while side-reactions became predominant at 60 °C. Starting with DS of 0.24, the samples were soluble both in water and dimethyl sulphoxide. The derivatives described are capable of forming polyelectrolyte complexes. The samples were stable at room temperature in aqueous solution at pH 2 and 7. Lower viscosities were found for samples with higher DS in aqueous solution at comparable molar mass.     

Synthesis and characterization of a multi-sensitive crosslinked injectable hydrogel based on Pluronic

This paper reports the construction of a novel multi-sensitive chemically crosslinked injectable hydrogel with strong mechanical strength by modifying Pluronic F127 responsive against temperature, pH and redox potential. Crosslinked polymer between benzaldehyde grafted Pluronic (P-A) and amine end capped Pluronic having disulfide linkage (P-B) have been synthesized and characterized with 1H NMR spectroscopy and GPC. The hydrogel under physiological conditions significantly altered sol-gel transition behaviors with much lower critical gelation concentrations and temperatures, compared to Pluronic hydrogels. The rheological characterization demonstrated that the moduli of the hydrogels were able to be tuned depending on molecular weight as well as pH, redox and temperature conditions.     

Synthesis and characterization of carboxylate waterborne cellulose emulsion based on cellulose acetate

With cellulose acetate (CA) as a base material, a novel environmentally friendly carboxylate waterborne cellulose acetate (CWCA) emulsion was synthesized via the method of self-emulsification. Taking advantage of acrylic acid, hydroxyethyl acrylate as a modifier, and isophorone diisocyanate as a bridging agent, the molecular structural design of CWCA dispersion was completed successfully, and the structure was confirmed by Fourier transform infrared spectroscopy (FTIR). In this work, the particle size and distribution of the stable CWCA dispersion with solid content of 22.6% are 115.6 and 0.158 nm, respectively. It was found that the microstructure of emulsion particles is a core-shell structure containing a hydrophilic carboxylate group as the shell and hydrophobic cellulose acetate molecular as the core. In addition, the hydrophobic behavior of CWCA film is presented as a contact angle of 109.9°. Furthermore, CWCA film provided a higher thermal decomposition temperature of 345.42 °C than that of CA film at the largest mass loss rate.     

Synthesis and characterization of a novel hydroxypropyl chitosan-graft-β-Cyclodextrin copolymer as potential drug carrier

Abstract

One of the most attractive fields in drug delivery is the design of nanoparticles that could be used to transport drugs into the target place at appropriate time. This paper describes the preparation of a novel hydroxypropyl chitosan-graft-β-cyclodextrin (HPCS-g-β-CD) copolymer using the 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) promoted condensation reaction. Structural characterization was finished with FTIR and ¹H NMR spectra, which confirmed the grafting of β-cyclodextrin (β-CD) onto hydroxypropyl chitosan (HPCS). The thermal properties were studied based on DSC and TGA analyses, which revealed the fact that grafting of β-CD onto HPCS resulted in obvious enhancement of the decomposition temperature of the copolymer. Aqueous solution of HPCS-g-β-CD copolymer was stable at pH 7-8 based on the Zeta potential test. The morphological characteristics were investigated by SEM, TEM and AFM analysis, and the results indicated that this copolymer had three-dimensional structure which was suitable for loading drugs.     

Synthesis and applications of quaternized highly branched polyacrylamide as a novel multi-site polymeric phase transfer catalyst

In current study, quaternized highly branched polyacrylamide (HBAA) was synthesized and used as an efficient multi-site polymeric phase transfer catalyst in nucleophilic substitution reactions and also in synthesis of α, β-unsaturated nitriles from reaction of acetonitrile and carbonyl compounds. The quaternized HBAA was synthesized via two steps. First, HBAA was synthesized via self-condensing vinyl polymerization of acrylamide at appropriate molar ratio of monomer to diperiodatocuprate(III). In the second step, 3-acrylamidopropyl trimethylammonium iodide was polymerized on peripheral area of the HBAA in the presence of diperiodatocuprate(III) solution again. The thermal behavior of HBAA and that of the quaternized HBAA were studied by DSC and TGA analysis. This phase transfer catalyst was easily recovered after reaction and reused several times without any loss of activity.     

High-efficacy antimicrobial cellulose grafted by a novel quaternarized N-halamine

A novel quaternarized N-halamine precursor (3-chloro-2-hydroxypropyl)-(5, 5-dimethylhydantoinyl-1-ylmethyl)-dimethylammonium chloride (CDDAC), has been synthesized by a very facile two-step reaction. The two-step synthesis of CDDAC occurred at room temperature with common reactors, so the production of CDDAC could be easily enlarged to an industrial scale. Without any work-up, the final reaction solution which contained CDDAC could be directly used as grafting solution. CDDAC could be effectively grafted onto the surface of cellulose by a dehydrochlorination reaction. CDDAC grafted on cellulose was converted to N-halamine structure which showed powerful antimicrobial property by a chlorination reaction in the diluted NaClO solution. The antimicrobial tests showed that the chlorinated cellulose grafted with CDDAC was capable of 5-log inactivation of S. aureus and E. coli within 5 min. Also, the washing durability and storage stability of chlorinated cellulose grafted with CDDAC were investigated.     

A novel polyacrylamide nanocomposite hydrogel reinforced with natural chitosan nanofibers

Polyacrylamide (PAM) was used as a matrix material for fabricating novel nanocomposite hydrogels reinforced with natural chitosan nanofibers (CNFs) via in situ free-radical polymerization. The nanocomposite's structure, strength, morphology and rheological properties were investigated. The results showed that the CNFs had a strong interaction with PAM through hydrogen and covalent bondings. The CNFs acted as a multifunctional cross-linker and a reinforcing agent in the hydrogel system. The compression strength and storage modulus of the nanocomposite hydrogels were significantly higher than those of the pure PAM hydrogels and the corresponding PAM/chitosan semi-interpenetrating polymer network (PAM-SIPN) hydrogels. The swelling ratio (SR) of the nanocomposite hydrogels was lower than that of the PAM hydrogel, but was similar to that of the PAM-SIPN hydrogel. Among the CNF contents used, the 1.5 wt% CNF loading level showed the best combined swelling and mechanical properties for the hydrogels.     

Synthesis and characterization of cellulose fibers grafted with hyperbranched poly(3-methyl-3-oxetanemethanol)

Hyperbranched poly(3-methyl-3-oxetanemethanol) (HBPO) was directly grafted from the surface of cellulose fibers (CF) through a surface hydroxyl group-initiated ring-opening polymerization of 3-methyl-3-oxetanemethanol (MOM). TOF–SIMS, XPS, AFM, ATR-FTIR, and TGA were utilized for characterizing the resultant HBPO-grafted cellulose fibers. The content of grafted HBPO is easily adjustable by controlling feeding dosage of the MOM. To verify the reactivity of hydroxyl groups in the grafted HBPO, poly(ε-caprolactone) (PCL) was further grafted from the HBPO-grafted cellulose surface.     

Electrodes and hydrogel electrolytes based on cellulose: fabrication and characterization as EDLC components

In the present work, the cellulose-based materials were manufactured and used as components of electrochemical double layer capacitors (EDLCs). The preparation method of cellulose membranes as well as composite electrodes containing cellulose as a binder was presented. These materials were prepared using for the first time ionic liquid/dimethyl sulfoxide (IL/DMSO) mixture solvent. Obtained components displayed a uniform structure, thermal stability, and good electrochemical properties. The electrochemical performances of these materials were studied in 2-electrode EDLC cells by common electrochemical techniques as cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS). The composite electrodes were investigated in three types of electrolytes: aqueous, organic, and ionic liquids. The cellulose membranes were, however, soaked in an aqueous electrolyte and tested as hydrogel polymer electrolytes. All investigated materials show high efficiency in terms of specific capacity. The studied cellulose-based capacitors exhibited specific capacitance values in the range of 20–22 F g^?1, depending on the type of applied electrolyte.     

Synthesis and properties of amino acid esters of hydroxypropyl cellulose

The amino acid esters of hydroxypropyl cellulose (HPC) [R′ = H ( 2a ), CH₃ ( 2b ), CH₂CH(CH₃)₂ ( 2c ), CH₂CONH₂ ( 2d ), CH₂CH₂CONH₂ ( 2e ), CH₂CH₂CH₂CH₂ NHOCOC(CH₃)₃ ( 2f )] were synthesized in good yield by the reaction of t‐butoxycarbonyl (t‐Boc)‐protected amino acids with hydroxy groups of HPC ( 1 ; molar substitution (MS), 4.61). The amino acid functionalities displaying varied chemical nature, shape, and bulk were utilized and the bulk of the substituent on the α‐carbon of amino acids was elucidated to be of vital significance for the observed degree of incorporation (DS_Est). The ¹H NMR spectra and elemental analysis were employed to determine the degree of incorporation of amino acid moiety (DS_Est) and almost complete substitution of the hydroxy protons was revealed for 2a , 2b , and 2f . The presence of the peaks characteristic of the carbonyl group in the FTIR spectra furnished further evidence for the successful esterification of HPC. The starting as well as the resulting polymers ( 1 and 2a – f ) were soluble in polar organic solvents; however, the esterification of 1 with bulky organic moieties resulted in an increased hydrophobicity as all of the amino acid‐functionalized polymers ( 2a – f ) were insoluble in water. The onset temperatures of weight loss of 2a – f were 175–230 °C, indicating fair thermal stability. The amino acid functionalization led to the enhanced polymer chain stiffness, and the glass transition temperatures of the derivatized polymers were 30–40 °C higher than that of 1 (T_g 3.9 °C; cf. T_g of 2a – f , 35.1–43.3 °C). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2326–2334, 2008     

羟丙基甲基纤维素作为水泥添加剂研究(一)

以三聚氯胺甲醛树脂磺酸盐（MS）为分散剂，羟丙基甲基纤维素衍生物为粘稠剂，研究了它们的复合物对混凝土材料的分散性与粘稠性及其它性能的影响，并探索了其作用机理．     

羟丙基甲基纤维素作为水泥添加剂研究(三)

以三聚氰胺甲醛树脂磷酸盐（MS）为分散剂，羟丙基甲基纤维素衍生物为粘稠剂研究了它们的复合物对混凝土材料的分散性与粘稠性及其它性能的影响，并探索了其作用机理。