Solvent‐free synthesis of 6‐deoxy‐6‐(ω‐aminoalkyl)amino cellulose

Cellulose p‐toluenesulfonic acid esters (TosCell) with degree of substitution (DS_Tos) between 0.8 and 1.4 were converted with ethylene diamine or tris(2‐aminoethyl)amine. In contrast to procedures published, the conversion was carried out without any solvent, i.e., the reagent (amines) was used as reaction medium yielding readily soluble products. Moreover, the absence of an additional solvent makes the recycling of both not‐consumed amine and precipitant easy. Recycling experiments proofed the possibility of reusing the isolated ethylene diamine. The DS of 6‐deoxy‐6‐(ω‐aminoalkyl)amino groups is between 0.71 and 0.93, which is in accordance with the functionalization pattern of tosyl cellulose and the ability of amines to displace primary tosylate moieties only. Attention must be paid to the precipitant used for the workup procedure; ¹³C NMR measurements revealed a formation of imine structures in case of precipitation with acetone. Precipitation in 2‐propanol did not lead to any side product. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43987.     

Alkyne cellulose for Huisgen [3 + 2] cycloaddition with azido‐terminated targets

Azido‐grafted cellulose has been reported widely applied for further functionalization by click chemistry. As an alternative method, we proposed alkyne‐grafted cellulose as a prototype molecule for Huisgen [3 + 2] cycloaddition with azido‐terminated target compounds. Alkyne cellulose was synthesized by acylation with prop‐2‐ynyl 5‐chloro‐5‐oxopentanoate and, subsequently cycloaddition with 4‐aminophenylazide, ethyl 2‐azidoacetate, and (S)‐2‐(Azidomethyl)‐1‐(tert‐butoxycarbonyl)pyrrolidine (Boc‐pyrrolidine azide) to form triazole cellulose in a click manner. The reactions were confirmed qualitatively by Fourier transform infrared and NMR spectroscopy and analyzed quantitatively with elemental analysis data. The results show that a degree of substitution of up to 1.91 was obtained for esterification and, in most cases, was preferred completely in a selective way for the primary hydroxyl groups at the O‐6 position and partially at the O‐2 and O‐3 positions. Cycloaddition conversions were found as high as 0.95, 0.99, and 0.99 for aniline–triazole cellulose, acetate–triazole cellulose, and Boc‐pyrrolidine‐triazole cellulose, respectively. Both esterification and cycloaddition were undertaken under mild conditions without additional heating. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44410.     

H3PW12O40·4H2O as an efficient catalyst for the conversion of cellulose into partially substituted cellulose acetate

The preparation of partial acetylation of cellulose derived from rice straw was catalyzed by phosphotungstic acid with various numbers of crystal water, and H₃PW₁₂O₄₀·4H₂O was found to be as effective catalyst. The yield of the cellulose acetate was significantly enhanced by converting cellulose directly isolated from rice straw into microcrystalline cellulose before acetylation. The optimization of the acetylation was investigated by varying the amount of catalyst and acetic anhydride as well as reaction conditions including reaction time and medium, and a degree of substitution (DS) value of 2.29 and yield of 62.9% were obtained under the optimized conditions. The structure and the formation of the acetylated product were confirmed by Fourier transform infrared spectroscopy (FTIR) and powder X‐ray diffraction (XRD) technique, the thermal properties were determined by thermal analysis including thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC), and the morphology was observed by scanning electron microscope (SEM). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41212.     

Fabrication of elastic composite hydrogels using surface‐modified cellulose nanofiber as a multifunctional crosslinker

We fabricate composite hydrogels using surface‐modified cellulose nanofiber (CNF) and N‐isopropylacrylamide (NIPAm) as a multifunctional crosslinker and monomer, respectively. We expect to produce unique network structures that lead to elastomeric properties rarely reported for CNF‐based materials. The modification of CNF is performed to introduce polymerizable vinyl groups onto the surface of CNF via condensation between the surface hydroxyl groups and 3‐(trimethoxysilyl)propylmethacrylate. The modification and morphology of the surface‐modified CNF (mCNF) are confirmed by FTIR, solid‐state NMR, and FE‐SEM, respectively. We conduct in situ radical polymerization under various conditions using mixtures of the mCNF aqueous suspension, NIPAm monomer, radical initiator, and catalyst. The mechanical properties of the obtained hydrogels (water content = 90 wt %) are evaluated. The gels can be elastically stretched to more than 700 times their original lengths and exhibit an apparent shape recovery with a small permanent deformation (～1/5 of the applied deformation under the gravity field). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42906.     

Homogeneous synthesis and characterization of polyacrylamide‐grafted cationic cellulose flocculants

In this work, cationic cellulose (CC) with different degrees of substitution (DS) was successfully synthesized by the reaction between cellulose and 3‐chloro‐2‐hydroxypropyl‐trimethylammonium chloride (CHPTAC) in a 7 wt % NaOH and 12 wt % urea aqueous solution. The structure of the CC was characterized by using elemental analysis, ¹H‐NMR, and FTIR. The DS values of CC ranged between 0.18 and 0.50, which could be obtained by adjusting the reaction temperature, reaction time, and molar ratio of CHPTAC to anhydroglucose unit of cellulose. The cationic cellulose–graft–polyacrylamide flocculant (CC‐g‐PAM) based on CC and polyacrylamide (PAM) was also synthesized in a homogeneous aqueous solution. The flocculation characteristics of CC and CC‐g‐PAM were evaluated in a kaolin suspension. The results showed that CC‐g‐PAM was an effective flocculant for the kaolin suspension under acidic or neutral conditions, and the flocculation efficiency was over 90%, while the CC showed better flocculation performance under alkaline conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43106.     

Synthesis of polyamidoxime chelating ligand from polymer‐grafted corn‐cob cellulose for metal extraction

A conventional free‐radical initiating process was used to prepare graft copolymers from acrylonitrile (AN) with corn‐cob cellulose with ceric ammonium nitrate (CAN) as an initiator. The optimum grafting was achieved with corn‐cob cellulose (anhydroglucose unit, AGU), mineral acid (H₂SO₄), CAN, and AN at concentrations of 0.133, 0.081, 0.0145, and 1.056 mol/L, respectively. Furthermore, the nitrile functional groups of the grafted copolymers were converted to amidoxime ligands with hydroxylamine under basic conditions of pH 11 with 4 h of stirring at 70°C. The purified acrylic polymer‐grafted cellulose and polyamidoxime ligand were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy analysis. The ligand showed an excellent copper binding capacity (4.14 mmol/g) with a faster rate of adsorption (average exchange rate = 7 min), and it showed a good adsorption capacity for other metal ions as well. The metal‐ion adsorption capacities of the ligand were pH‐dependent in the following order: Cu²⁺ > Co²⁺ > Mn²⁺ > Cr³⁺ > Fe³⁺ > Zn²⁺ > Ni²⁺. The metal‐ion removal efficiency was very high; up to 99% was removed from the aqueous media at a low concentration. These new polymeric chelating ligands could be used to remove aforementioned toxic metal ions from industrial wastewater. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40833.     

Hydroxyethyl cellulose hydrogel modified with tannic acid as methylene blue adsorbent

This work developed an effective way to improve the methylene blue (MB) adsorption performance of cellulose-based hydrogel by modified with tannic acid (TA). HEC-co-p(AA-AM)/TA hydrogel was synthesized by grafting of acrylic acid (AA) and acrylamide (AM) onto hydroxyethyl cellulose (HEC), followed by modified with TA. Fourier transform infrared spectroscopy manifested that AA and AM were successfully grafted onto the hydrogel, and TA was immobilized in the hydrogel. Field emission scanning electron microscope demonstrated that the hydrogel after TA modification had a homogeneous pore structure. Brunauer-Emmett-Teller (BET) surface areas, total pore volume, and average pore diameters of the hydrogel are 11.821 m² g⁻¹, 0.0641 cm³ g⁻¹, and 2.538 nm, respectively. The high swelling ratio (1179.2 g g⁻¹ in deionized water) was in favor of the MB adsorption. The results of the adsorption experiments illustrated that HEC-co-p(AA/AM) hydrogel had excellent MB adsorption performance. As the pH increases, the electrostatic attraction is enhanced, and the adsorption capacity is improved. The adsorption process was more fit with pseudo-second-order kinetics, and the maximum adsorption capacity (3438.27 mg g⁻¹) was determined by Langmuir model. Thermodynamic studies suggested that the adsorption process is spontaneous, exothermic, and entropy reduction. X-ray photoelectron spectroscopy analysis confirmed that MB molecules were reacted with the oxygen atoms in hydroxyl and carboxyl groups by ion-exchange. High reusability demonstrated that the hydrogel could be a potential candidate for removal cationic dye from industrial effluents.     

Synthesis of a montmorillonite‐supported titania nanocomposite with grafted cellulose as a template and its application in photocatalytic degradation

We report a study on the synthesis of anatase titania (TiO₂) particles with the sol–gel method at room temperature. We immobilized the particles on a grafted‐cellulose intercalated montmorillonite (MMT). This nanocomposite, cellulose‐g‐poly(4‐vinyl pyridine)/MMT/TiO₂, could be applied in the photocatalytic degradation of organic pollutants efficiently because of the addition of a sorbent, the grafted cellulose. The synthesized nanocomposite was characterized with Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. Methyl orange was used as a model molecule to study photocatalytic degradation. The nanocomposite exhibited a better photocatalytic activity than in the absence of the grafted cellulose. The kinetics of the photocatalytic degradation could be described by pseudo‐first‐order rate law. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42627.     

Oxidation of γ‐irradiated microbial cellulose results in bioresorbable,highly conformable biomaterial

Conformability to tissues and adequate mechanical strength are clinically useful properties of resorbable biomaterials used in soft tissue repair. Microbially derived cellulose is attractive as a high strength, highly conformable, and biocompatible material for tissue repair, but is not naturally resorbable. Here we show that controlled oxidation of microbial cellulose sheets that have been pre‐irradiated with γ‐radiation results in a resorbable and fully conformable membrane that can be rapidly rehydrated in aqueous fluids. In vitro studies showed that degradation of the resorbable membranes occurs in two major phases: (1) initial rapid degradation of about 70–80% of the entire sample followed by (2) slower degradation of an additional 5–10% which eventually levels off leaving a small amount of nonresorbable material. In vivo, prototype materials showed marked degradation at all time points, with the most rapid degradation occurring in the first 2–4 weeks. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39995.     

Oxoacetohydrazide‐functionalized cellulose with enhanced adsorption performance

A simple and environmental friendly oxoacetohydrazide functionalization method is developed to convert the straw cellulose into high performance adsorbents for effective Pb(II) removal. The adsorption experimental results demonstrated that the resultant oxoacetohydrazide‐modified cellulose (OMC) possesses a dramatically improved Pb(II) adsorption capacity (82.9 mg/g), which is over six times of that for the unmodified celluloses (13.6 mg/g). The mechanistic studies confirm that the markedly enhanced Pb(II) adsorption capability of OMC can be attributed to the formation of N‐Pb‐N bonds resulting from the strong chelating interactions of Pb(II) with oxoacetohydrazide. Also, the OMC shows an excellent reusability, capable of retain 95% of its original Pb(II) adsorption capacity after three consecutive adsorption cycles. The findings of this work pave a way to transform the agricultural byproducts into high performance functional materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42950.     

Morphological,thermal, and mechanical properties of poly(ε‐caprolactone)/poly(ε‐caprolactone)‐grafted‐cellulose nanocrystals mats produced by electrospinning

Electrospun nanocomposites of poly(ε‐caprolactone) (PCL) incorporated with PCL‐grafted cellulose nanocrystals (PCL‐g‐CNC) were produced. PCL chains were grafted from cellulose nanocrystals (CNC) surface by ring‐opening polymerization. Grafting was confirmed by infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). The resulting PCL‐g‐CNC were then incorporated into a PCL matrix at various loadings. Homogeneous nanofibers with average diameter decreasing with the addition of PCL‐g‐CNC were observed by scanning electron microscopy (SEM). PCL‐g‐CNC domains incorporated into the PCL matrix were visualized by transmission electron microscopy (TEM). Thermal and mechanical properties of the mats were analyzed by differential scanning calorimetry (DSC), TGA and dynamic mechanical analysis (DMA). The addition of PCL‐g‐CNC into the PCL matrix caused changes in the thermal behavior and crystallinity of the electrospun fibers. Significant improvements in Young's modulus and in strain at break with increasing PCL‐g‐CNC loadings were found. These results highlighted the great potential of cellulose nanocrystals as a reinforcement phase in electrospun PCL mats, which can be used as biomedical materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43445.     

Rapeseed oil‐based polyurethane foams modified with glycerol and cellulose micro/nanocrystals

A rapeseed oil‐based polyol (ROPO) was synthesized using chemical modification of the rapeseed oil (RO) by epoxidation reaction followed by oxirane ring‐opening with diethylene glycol. The ROPO was used in the formulation of low‐density green polyurethane (PU) foams. The use of glycerol as hydroxyl component, water as a reactive blowing agent and micro/nanocellulose (MNC) as a reinforcement increases the content of natural components in the formulations with important effects on the final foam properties. The ROPO and their intermediate products are characterized by analytical techniques and FTIR spectroscopy, while the final PU foams are characterized by morphological and mechanical analysis. The results show that the addition of glycerol increases the modulus and yield stress. The incorporation of MNC in small amounts is enough to increase the modulus at low temperatures. Both modifiers cause an increase in water absorption and the fragility of the cell walls, reflected in the micrographs of the foams. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41602.     

High‐strength regenerated cellulose fibers spun from 1‐butyl‐3‐methylimidazolium chloride solutions

High‐performance regenerated cellulose fibers were prepared from cellulose/1‐butyl‐3‐methylimidazolium chloride (BMIMCl) solutions via dry‐jet wet spinning. The spinnability of the solution was initially evaluated using the maximum winding speed of the solution spinning line under various ambient temperatures and relative humidities in the air gap. The subsequent spinning trials were conducted under various air gap conditions in a water coagulation bath. It was found that low temperature and low relative humidity in the air gap were important to obtain fibers with high tensile strength at a high draw ratio. From a 10 wt % cellulose/BMIMCl solution, regenerated fibers with tensile strength up to 886 MPa were prepared below 22 °C and relative humidity of 50%. High strengthening was also strongly linked with the fixation effect on fibers during washing and drying processes. Furthermore, an effective attempt to prepare higher performance fibers was conducted from a higher polymer concentration solution using a high molecular weight dissolving pulp. Eventually, fibers with a tensile strength of ～1 GPa and Young's modulus over 35 GPa were prepared. These tensile properties were ranked at the highest level for regenerated cellulose fibers prepared by an ionic liquid–based process. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45551.     

Regioselective substitution of 2‐isocyanatoethylmethacrylate onto cellulose

Cellulose is a well‐known versatile polymer that presents a wide range of material properties via the substitution and grafting reactions of its hydroxyl groups. Because of their commercial potential, combinations of cellulose and vinyl polymers have been examined with various grafting methods. In this study, the condensation reactions of regioselective and nonregioselective substitution with 2‐isocyanatoethylmethacrylate were performed in a homogeneous solvent system of dimethyl acetamide/lithium chloride. The successful substitution was confirmed by Fourier transform infrared spectroscopy, ¹H‐NMR, cross‐polarization/magic angle spinning ¹³C‐NMR, thermogravimetric analysis, and X‐ray diffraction. The substituted celluloses showed excellent thermal stability and a different polymorph with a depressed cellulose–intrinsic polymorphic phase. The 2‐isocyanatoethylmethacrylate side chain seemed to expand the intermolecular distance with enhanced chain mobility and trigger the formation of a novel crystalline polymorph with a dramatically improved thermal stability. This investigation provided us with a useful understanding of the modification of cellulose with spatial distribution control for advanced future applications requiring a combination of cellulose with vinyl polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and application of cotton‐based chelate fibers grafted with poly(1‐vinyl‐1,2,4‐triazole) side chains

Cotton‐based chelate fibers grafted with poly(1‐vinyl‐1,2,4‐triazole) (PVTAZ) side chains were synthesized facilely by ozone‐induced graft polymerization of 1‐vinyl‐1,2,4‐triazole (VTAZ) monomer onto cotton fibers. The synthesis conditions were optimized to improve the yield and mechanical strength of the products. The obtained cotton‐g‐PVTAZ fibers were characterized and evaluated for batch adsorption of heavy metal ions from aqueous solutions. The maximum adsorption capacity of Ag(I), Pb(II), and Cu(II) on the fibers at pH 6.8 was 522, 330, and 184 mg/g, respectively. At 30% graft yield, the Young's modulus of cotton fiber increased about 26.5%, and its adsorption capacities of Ag(I), Pb(II), and Cu(II) increased about 2.6, 1.9, and 1.4 times, respectively. After washed with 0.1 mol/L HNO₃ solutions, the adsorbed metal ions were eluted, and the regenerated cotton‐g‐PVTAZ fibers could be used repeatedly for water treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41617.     

Preparation,characterization and the effect of carboxymethylated chitosan–cellulose derivatives hydrogels on wound healing

Oxidized carboxymethyl cellulose (OCMC) was prepared by an oxidation reaction of carboxymethyl cellulose in the presence of sodium periodate. In situ crosslinked hydrogels were obtained through the crosslinking reaction between the active aldehyde of OCMC and the amino groups of the carboxymethyl chitosan (CMCS). The structure of the hydrogels was characterized by FTIR and scanning electron microscopy. Gelation time test showed that the hydrogel had the shortest gelation time of 24 s. The equilibrium fluid content, which represented the swelling degree, was evaluated and we found that the pH increased from 3.0 to 9.0, the equilibrium fluid content increased, and the highest equilibrium fluid content reached 312.83% as pH = 9.0. The wound healing efficacy of the hydrogel was evaluated in experimental deep second degree burns using a rat model. Results indicated that the wound covered with hydrogel was completely filled with new epithelium within 2 weeks, without any significant adverse reactions. The in situ crosslinked hydrogel fulfilled many critical elements in a wound dressing material. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Controllable synthesis of cellulose/methylene bisacrylamide aerogels for enhanced adsorption performance

Cellulose-based aerogels have been regarded as potential adsorbent materials because of their unique structural features and chemical stability. Herein, we prepared the composite aerogels containing cellulose and N,N′-methylene bisacrylamide (MBA) using N-methylmorpholine-N-oxide (NMMO) as a green solvent via a freeze-drying process. Owing to the strong chemical interaction between CC bonds of MBA and the functional groups of cellulose, as-obtained cellulose/MBA aerogels present favorable MBA-induced thermal/mechanical stable three-dimensional network structure, in which the abundant macroporous structure, low density and high porosity lead to a significantly enhanced adsorption capacity (260.31 mg∙g⁻¹) toward congo red dye in aqueous solution compared with the pure cellulose aerogels. Moreover, the effect of the cellulose concentration and cross-linking degree on the morphology and adsorption properties for cellulose/MBA aerogels was systematically investigated. This present work provides a low-cost and environmental-friendly synthesis method for designing the functionalization of cellulose-based aerogel, which may be achieved the advanced performance in wastewater treatment.     

Bifunctional cellulose derivatives for the removal of heavy‐metal ions and phenols: Synthesis and adsorption studies

In this article, we report a study of the design and synthesis of a bifunctional cellulose derivative on the removal of phenols and heavy‐metal ions in wastewater treatment. A radical polymerization was performed in an ionic liquid, 1‐allyl‐3‐methylimidazolium chloride, to graft two monomers, butyl methacrylate and 4‐vinyl pyridine, on the backbone of cellulose. The effects of the five reaction conditions on the yield of final products were evaluated. The grafted celluloses were characterized by means of Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. Adsorption experiments were carried out on the cellulose‐g‐poly(butyl methacrylate‐co‐4‐vinyl pyridine) to evaluate the capacity of the removal of 2,4‐dichlorophenol (2,4‐DCP) and Cu(II) in water. The adsorption isotherms were measured at five temperatures and interpreted by a Langmuir model of adsorption. The thermodynamics of the adsorption suggested that the binding process was mildly exothermic for Cu(II) and endothermic for 2,4‐DCP. Kinetic studies were interpreted with a pseudo‐second‐order adsorption model. The process of the adsorption of 2,4‐DCP could be described overall by the model, whereas the adsorption of Cu(II) involved two processes. This was due to adsorption both on the surface and inside the adsorbent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41830.     

Study on quaternary ammonium modified tentacle‐type cellulose beads and its adsorption for

A novel anion exchange resin based on cellulose has been prepared to adsorb for the urgent demand of silver and the high toxicity of metal‐cyanide complexes. Quaternary ammonium groups were grafted onto cellulose beads as main active sites in tentacle‐type through a series of chemical reactions. The substitution degree of each reaction was determined to be about 0.854, 2.125, and 2.899 mmol g^?1, respectively. The resin exhibited excellent spherical shape with microporous structure by the observation of optical microscopy and scanning electron microscope. Moreover, the adsorption experiments demonstrated the adsorption was fast in alkaline condition. Fitting the data into isotherm and kinetic models gave the conclusion that the adsorption behavior matched better with Langmuir model and pseudo‐second‐order kinetic in initial time followed pseudo‐first‐order kinetic model in later phase. The equilibrium adsorption capacity was determined to be 3.016 mmol g^?1. With the advantages of high capacity, short equilibrium time, and alkaline resistance, the resin would be considered to a top‐priority adsorbent for the separation of . © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40987.     

Polyethylenimine-modified sugarcane bagasse cellulose as an effective adsorbent for removing Cu(II) from aqueous solution

Polyethylenimine-modified sugarcane bagasse cellulose (SBCMP), as a new adsorbent, was synthesized by the reaction of polyethylenimine (PEI) with sugarcane bagasse cellulose and glutaraldehyde. The adsorption of Cu(II) by SBCMP was pH-dependent, and the higher removal efficiency of Cu(II) appeared in the range of pH 3.0–6.0. The adsorption isothermal data fitted well with the Langmuir model, and the maximum adsorption capacity of SBCMP was up to 107.5 mg/g. The adsorption kinetics was best described by the pseudo-second-order kinetic. The adsorption of Cu(II) by SBCMP was unfavorable at high temperatures, and thermodynamic analyses implied that the adsorption of Cu(II) by SBCMP was an exothermic reaction. Fourier transform infrared spectroscopy (FT-IR) combined with X-ray photoelectron spectroscopy (XPS) revealed that Cu(II) adsorption on SBCMP mainly controlled by the nitrogen atoms of  NH group in PEI. The results of regeneration cycles showed that SBCMP was suitable for reuse in the adsorption of Cu(II) from aqueous solution. These experimental results suggested that SBCMP is expected to be a new biomass adsorbent with high efficiency in removing Cu(II) from wastewater.