Cellulose Graft Copolymers Research Articles

Preparation of acrylamide and carboxymethyl cellulose graft copolymers and the effect of molecular weight on the flocculation properties in simulated dyeing wastewater under different pH conditions

In this study, graft copolymers with different graft ratios (GRs) and molecular weights (MWs) were prepared by water bath polymerization using acrylamide (AM) and carboxymethyl cellulose (CMC) as substrates; additionally, the best preparation parameters were provided. The MW of the copolymer was inversely correlated with the GR (R = −0.82). The obtained graft copolymer was characterized by FTIR, 1H NMR, XPS and DSC. The results showed that CMC and AM were successfully copolymerized and the thermal stability of the product is improved. The graft copolymers with different MWs were used to flocculate a simulated dyeing wastewater at pH values of 3, 5, 7, 9 and 11. The results showed that as the molecular weight of the graft copolymers increased, the average flocculation settling ratio decreased drastically from 61.2% to 19.4% at pH 3, and the higher the MW, the better the flocculation settling performance. But the average settling ratio increased sharply at pH 11, and the increase grew from 21.0% to 50.3%. The larger the MW, the more obvious the decrease in flocculation sedimentation performance. The supernatant turbidity was reduced from 13324 NTU to less than 150 NTU, and the turbidity removal ratio exceeded 99%. The flocculation mechanism was discussed.

Self-associating cellulose-graft-poly(ε-caprolactone) to design nanoparticles for drug release.

The growing interest in the use of polysaccharides nanoparticles for biomedical applications is related to the recent progresses on the synthesis of cellulose-based polymers with the specific functionalities. In particular, cellulose graft copolymers are emerging as amphiphilic materials suitable to fabricate smart nanoparticles for drug delivery applications. In this work, a cellulose-graft-poly(ε-caprolactone) (cell-g-PCL) was synthetized and characterized by FTIR, TGA and DSC in order to validate the synthesis process. We demonstrated that fast evaporation processes promoted cell-g-PCL self-assembly to form nanomicellar structures with hydrodynamic radius ranged from 30 to 60 nm as confirmed by TEM analysis. Moreover, the application of controlled electrostatic forces on solvent evaporation - namely electrospraying - allowed generating round-like nanoscaled particles, as confirmed by SEM supported via image analysis. We demonstrated also that sodium diclofenac (DS) drastically influenced the mechanism of particle formation, favoring the deposition of erythrocyte-like particles with highly concave surfaces, not penalizing the encapsulation efficiency of nanoparticles (>80%). The release profile showed a fast delivery of DS - about 60% during the first 24 h - followed by a sustained release - about 20% during the next 6 days - strictly related to the peculiar weak interactions among amphiphilic polymer segments and water molecules, thus suggesting a successful use of electrosprayed cell-g-PCL nanoparticles for therapeutic treatments in nanomedicine.

The toughening of polymeric glasses using cellulose without sacrificing transparency

The development of cellulose graft copolymers has been intensively studied during recent years. Our previous works have demonstrated that cellulose graft strategy can greatly improve the mechanical properties of thermoplastic elastomers. However, the effect of cellulose graft strategy on glassy polymers is still unknown. Herein, Cellulose-graft-poly(methyl methacrylate) (Cell-g-PMMA) copolymers were synthesized by activators regenerate by electron transfer atom transfer radical polymerization (ARGET ATRP). Two kinds of celluloses, microcrystalline cellulose (MCC) and wood pulp cellulose (Pulp) were used as starting materials. Thermal behavior, transparency, and mechanical properties of these graft copolymers were investigated. Compared with the brittle fracture of PMMA, a typical ductile fracture was observed in both MCC-g-PMMA and Pulp-g-PMMA copolymers, which showed similar transparency as linear PMMA film. The tensile toughness of MCC-g-PMMA copolymers was almost 7 times to that of linear PMMA. Furthermore, the toughness of Pulp-g-PMMA copolymers was even better than that of MCC-g-PMMA copolymers.

Functionalization of cellulose as imprinted adsorbent for selective adsorption of matrine

ABSTRACTA novel molecular imprinted polymer (MIP) based on cellulose is fabricated for separation of matrine. Cellulose graft copolymer was first synthesized from cotton linter by atom transfer radical polymerization in ionic liquid with the acrylamide as monomer. Then, the prepared graft copolymer underwent sulfomethylation and subsequent crosslinking in the matrine solution. Effects of the parameters on the reaction degree were discussed, and the structural, component, and morphological characterization of the products were also conducted. The ability of the obtained cellulose‐based MIP (MIP‐SPAM) to adsorb matrine was evaluated by batch adsorption. Results showed that the sorption process was pH dependent, spontaneous, endothermic, and followed the Langmuir adsorption isotherm. Kinetics study revealed that pseudo‐second‐order was closed to the experimental data and both of the membrane diffusion and intraparticle diffusion controlled the matrine adsorption. Moreover, MIP‐SPAM possessed higher selective sorption property for matrine compared to the corresponding nonimprinted polymer. Finally, the MIP‐SPAM could be repeatedly used for five times without any significant loss in the initial binding affinity. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48392.

Cellulose graft copolymers toward strong thermoplastic elastomers via RAFT polymerization

A novel cellulose-based macromolecular chain transfer agent (Cell-CTA) was designed to prepare cellulose graft copolymers via reversible addition-fragmentation chain transfer (RAFT) polymerization. A series of cellulose-graft-poly(n-butyl acrylate-co-acrylamide) (Cell-g-P(BA-co-AM)) copolymers were synthesized as thermoplastic elastomers (TPEs). In this molecular structure, cellulose chains were used as semirigid backbones, whereas the P(BA-co-AM) side chains acted as the rubbery matrix. The glass transition temperatures (Tgs) of Cell-g-P(BA-co-AM) copolymers can be manipulated by tuning the molar ratios between BA and AM during the polymerization process. These cellulose graft copolymers show typical elastomeric behavior and can possess strong tensile strength and high toughness according to the mechanical tests. The random distributed amide groups in AM units can form strong self-complementary hydrogen bonding as supramolecular cross-linking points in the graft copolymers. Morphological results demonstrate the homogeneous state of these Cell-g-P(BA-co-AM) copolymers. This convenient and robust grafting strategy can be further utilized to generate various cellulose-based graft copolymers as sustainable materials via rational molecular design.

Metal-free ATRP “grafting from” technique for renewable cellulose graft copolymers

Photoinduced metal-free “grafting from” atom transfer radical polymerization (ATRP) has been successfully applied to the fabrication of renewable cellulose graft copolymers with the aid of 2-bromo-2-phenylacetyl ester-modified ethyl cellulose as the macroinitiator.

Graft copolymers of carboxymethyl cellulose with N-vinylimidazole: synthesis and application for drug delivery

Graft copolymers of sodium salt of carboxymethyl cellulose and N-vinylimidazole with different contents of the latter are synthesized by radical polymerization. Polymerization kinetics for all samples is researched by copolymer composition determination by UV spectroscopy, and it was found that it lasted 180 min. Percent of grafting calculated from FTIR data is in the range 31–59%, which correlated with GPC and static light scattering data. Aqueous solutions of the synthesized copolymers are characterized by dynamic light scattering (DLS), transmission electron microscopy, and zeta potential measurement. It was established that macromolecular particles of all synthesized copolymers possess non-spherical shape and negative electrokinetic potential value. The hydrodynamic radii of the polymer coils are 120–152 nm. It was found by DLS that macromolecular coils of all copolymers are stable in 0.15 M NaCl aqueous solution and in the physiological pH range which allows to apply them as vectors for targeted drug delivery. Interaction between paclitaxel (Ptx) and Na-CMC-g-PVI copolymer was studied by UV spectroscopy, FTIR, and TEM. Copolymer and Ptx complex formation proceeds by interaction of imidazole cycles and methylene backbone of Na-CMC-g-PVI copolymer and C=O groups and aromatic rings of Ptx. In vitro release kinetics was also researched in acidic and neutral media at 38 °C. Particularly, full release of paclitaxel is reached after 144 h. Release process of Ptx from copolymer particles is described by Korsmeyer–Peppas kinetic model and limited by molecular diffusion.

Removal of organic dyes and metal ions by cross-linked graft copolymers of cellulose obtained from the agricultural residue

Cellulose extracted from agricultural residue, rice husk was functionalized through free radical grafting with a binary vinyl monomer mixture of 2-acrylamido-2-methylpropane sulfonic acid and acrylic acid in the presence of N,N'-methylene bisacrylamide cross-linker. To ascertain the grafting, the synthesized copolymer, Cell-g-AASO3H-co-AAc was characterized by FESEM, FTIR, XRD and thermal analytical techniques. The swelling behavior of the grafted copolymer, analyzed as a function of pH followed the order 7.0 > 9.4 > 2.2. The as-synthesized graft copolymer was used as an adsorbent for the removal of model malachite green, crystal violet, congo red dyes and Ni(II) and Cu(II) metal ions from aqueous solutions. The adsorption characteristics of the grafted copolymer were studied as a function of contact time, temperature, pH, and concentration. Cationic dyes were adsorbed maximum at pH 7.0 in 90 min contact time, whereas anionic dye was removed under acidic pH of 2.2 in 8 h. Maximum adsorption of Ni(II) and Cu(II) ions was observed at pH 6.0 and temperature of 30 °C after a contact time of 120 min. Among the various kinetic and adsorption isotherm models, the experimental adsorption data were best fitted in pseudo-second-order kinetic model and Langmuir isotherm model for organic dyes and metal ions. From Langmuir adsorption isotherm, maximum sorption capacities of 112.74 and 109.77 mg/g was reported for Ni(II) and Cu(II) ions, respectively. The current study thus proves that the Cell-g-AASO3H-co-AAc copolymer can efficiently be used as an adsorbent for uptake of harmful cationic as well as anionic dyes and toxic metal ions from industrial wastewater.

СИНТЕЗ ГРАФТ-СОПОЛИМЕРОВ КАРБОКСИМЕТИЛЦЕЛЛЮЛОЗЫ С N-ВИНИЛИМИДАЗОЛОМ И ИССЛЕДОВАНИЕ КИНЕТИКИ ВЫСВОБОЖДЕНИЯ ПРОТИВООПУХОЛЕВОГО ПРЕПАРАТА ПАКЛИТАКСЕЛ ИЗ АССОЦИАТА С СОПОЛИМЕРОМ

Графт-сополимеры карбоксиметилцеллюлозы получены радикальной полимеризацией в растворе в присутствии перекиси водорода. Сополимеры охарактеризованы методами ИК- УФ-спектороскопии, гель-проникающей хроматографией и статическим светорассеянием. Изучение водных растворов сополимеров методами динамического светорассеяния, лазерного допплеровского микроэлектрофореза и просвечивающей электронной микроскопии показало, что частицы сополимеров имеют несферическую форму и характеризуются совокупным отрицательным зарядом частиц. Установлено, что взаимодействие между частицами сополимеров и Паклитакселом в водном растворе носит физический характер. Кинетика высвобождения препарата из комплекса с сополимером описывается кинетической моделью Корсмейера-Пеппаса и не подчиняется законам Фика.
 
 Данные ИК-спектроскопии, просвечивающей электронной микроскопии, лазерного допплеровского микроэлектрофореза получены на оборудовании Центра коллективного пользования научного оборудования ВГУ.

Water absorption and viscosity behaviour of thermally stable novel graft copolymer of carboxymethyl cellulose and poly(sodium 1-hydroxy acrylate)

A novel thermally stable hydrolysed carboxymethyl cellulose-g-poly(sodium 1-hydroxy acrylate) i.e. CMC-g-PNaHA graft copolymer was synthesized from the CMC and vinyl monomer 5-methylene-2-isopropyl-1,3-dioxolan-4-one (MD) in an aqueous medium using an initiator followed by transformation of resulting CMC-g-PMD via alkaline hydrolysis. The graft copolymerization is confirmed by the Fourier transform infrared spectroscopy (FT-IR), Nuclear magnetic resonance spectroscopy (NMR) and X-ray diffractometer (XRD). The influence of the CMC and PNaHA content on the properties of the resulting hydrolysed CMC-g-PNaHA graft copolymer was investigated. In comparison with the PNaHA polymer, the resulted hydrolysed CMC-g-PNaHA grafted copolymer has improved thermal stability, water absorption properties, viscosity and weight-average molecular weight.

Grafted cellulose: a bio-based polymer for durable applications

Grafting is one of the best method for the modification of physicochemical properties of the cellulose. The –OH groups present at C2, C3, and C6 atoms of each β-d-glucopyranose units of cellulose chains are the most susceptible active sites for the grafting of many monomer units or polymers for the formation of a variety of cellulose-based graft copolymers with advanced properties and potential applications as compared to the bare cellulose. In this review article, a brief introduction to get an insight into the structural features of cellulose is given. After that, the potential applications and recent advancements of various cellulose graft copolymers made in fields of controlled drug delivery, adsorption of harmful, toxic and non-biodegradable dyes from industrial effluents, sorption of heavy metal ions from aqueous medium, modification of electrolyte, electrodes and separators of the modern age Lithium ion batteries, and fabrication of smart and innovative food packaging materials are reviewed.

Sustainable Elastomers from Renewable Biomass.

Sustainable elastomers have undergone explosive growth in recent years, partly due to the resurgence of biobased materials prepared from renewable natural resources. However, mounting challenges still prevail: How can the chemical compositions and macromolecular architectures of sustainable polymers be controlled and broadened? How can their processability and recyclability be enabled? How can they compete with petroleum-based counterparts in both cost and performance? Molecular-biomass-derived polymers, such as polymyrcene, polymenthide, and poly(ε-decalactone), have been employed for constructing thermoplastic elastomers (TPEs). Plant oils are widely used for fabricating thermoset elastomers. We use abundant biomass, such as plant oils, cellulose, rosin acids, and lignin, to develop elastomers covering a wide range of structure-property relationships in the hope of delivering better performance. In this Account, recent progress in preparing monomers and TPEs from biomass is first reviewed. ABA triblock copolymer TPEs were obtained with a soft middle block containing a soybean-oil-based monomer and hard outer blocks containing styrene. In addition, a combination of biobased monomers from rosin acids and soybean oil was formulated to prepare triblock copolymer TPEs. Together with the above-mentioned approaches based on block copolymers, multigraft copolymers with a soft backbone and rigid side chains are recognized as the first-generation and second-generation TPEs, respectively. It has been recently demonstrated that multigraft copolymers with a rigid backbone and elastic side chains can also be used as a novel architecture of TPEs. Natural polymers, such as cellulose and lignin, are utilized as a stiff, macromolecular backbone. Cellulose/lignin graft copolymers with side chains containing a copolymer of methyl methacrylate and butyl acrylate exhibited excellent elastic properties. Cellulose graft copolymers with biomass-derived polymers as side chains were further explored to enhance the overall sustainability. Isoprene polymers were grafted from a cellulosic backbone to afford Cell-g-polyisoprene copolymers. Via cross-linking of these graft copolymers, human-skin-mimic elastomers and high resilient elastomers with a well-defined network structure were achieved. The mechanical properties of these resilient elastomers could be finely controlled by tuning the cellulose content. As isoprene can be produced by engineering of microorganisms, these elastomers could be a renewable alternative to petroleum products. In summary, triblock copolymer and graft copolymer TPEs with biomass components, skin-mimic elastomers, high resilient biobased elastomers, and engineering of macromolecular architectures for elastomers are discussed. These approaches and design provide us knowledge on the potential to make sustainable elastomers for various applications to compete with petroleum-based counterparts.

Cellulose-Based Gels

Cellulose is the most available biomacromolecule in nature with the properties of renewability, biodegradability, biocompatibility, and environmental friendliness. Cellulose and its derivatives are excellent building blocks for fabrication of gels. In this review, the principles for preparing cellulose-based gels are summarized in detail. Considering the native properties of cellulose and its derivatives, chemical and/or physical crosslinking can be introduced during the preparation of cellulose-based gels. The chemical and physical crosslinking approaches are classified alongside the introduction of new concepts in polymer science, such as supramolecular interactions. Cellulose graft copolymers are another kind of building block in the fabrication of cellulose-based gels. The properties of gels can be tailored by the chemical structure of the graft chains. Cellulose-based gels can be applied in many fields depending on their properties.

The effect of extractant on the removal of heavy metal ions by thermoresponsive cellulose graft copolymer

The adsorption and desorption property of the thermoresponsive cellulose-graft-poly(N-isopropyl acrylamide) (PNIPAM) copolymer for Cu(II), Pb(II), Ni(II) and Cd(II) ions have been investigated by temperature swing adsorption (TSA) process. In this study, sodium lauryl sulfate (SLS) and dodecyltrimethylammonium chloride (DTAC) which interact with heavy metals were chosen as the extractants and their effect on the adsorption capacity of cellulose copolymer was investigated. The adsorption (50°C) and desorption (10°C) processes were performed by temperature swing. The kinetic data were found to follow the pseudo-second order model and intraparticle diffusion is not the only rate controlling step. In the non-competitive medium, the adsorption of heavy metal ions occurred in the order Cd(II)>Cu(II)>Ni(II) in the presence of SLS, but in the case of DTAC it followed the order Cu(II)>Cd(II)>Ni(II)>Pb(II).

Solid state thermal degradation behaviour of graft copolymers of carboxymethyl cellulose with vinyl monomers

The graft copolymer of sodium carboxymethyl cellulose (CMC) with acrylamide (ACM), dimethylacrylamide (DMA), N-vinyl pyrrolidone (NVP), 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) and vinyl caprolactum (VCL) were synthesized in nitrogen atmosphere by employing redox initiators. The integral procedural decomposition temperature (IPDT) of CMC and its graft copolymer with ACM, DMA, AMPS, NVP and VCL have been found to be 274°C, 375°C, 421°C, 404°C, 466°C and 331°C, respectively. The higher value of IPDT showed more thermal stability. Among all five graft copolymers, the graft copolymer of CMC with NVP is thermally more stable and VCL grafted copolymer was found least thermally stable. The higher char yield and final decomposition temperature (FDT) were obtained in the case of more thermally stable graft copolymer. All five graft copolymers have shown more than one Tmax, which suggests that degradations were multistep process.

Preparation of an Antibacterial Poly(ionic liquid) Graft Copolymer of Hydroxyethyl Cellulose.

Poly(ionic liquid)s (P(IL)s) of different degrees of polymerization (10, 50, and 100) were prepared via RAFT polymerization using an alkyne-terminated xanthate as transfer agent, with a monomer conversion of up to ∼80% and a ĐM of 1.5 for P(IL)100. Subsequently, P(IL) chains were coupled to (15)N-labeled azido-functionalized hydroxyethyl cellulose (HEC), forming graft copolymers of HEC with different chain length and graft densities, which were characterized using ((13)C and (15)N) CP-MAS NMR and FT-IR spectroscopies. The antibacterial activities of HEC-g-P(IL)s were tested against Escherichia coli and Staphylococcus aureus and were comparable to ampicillin, a well-known antibiotic, demonstrating efficient activity of the graft copolymers against bacteria. Moreover, HEC-g-P(IL)s were slightly more effective against E. coli than S. aureus. A decrease in graft density of P(IL)10 on the HEC backbone decreased the activity of the graft copolymers against both bacteria. These findings suggest that HEC-g-P(IL) could find applications as an antiseptic compound, for example, in paint formulation.

Graft copolymers of microcrystalline cellulose as reinforcing agent for elastomers based on natural rubber

ABSTRACTIn the present study, free radical graft copolymerization of acrylic monomers and microcrystalline cellulose (MCC) was applied to develop a biopolymer for natural rubber reinforcements. The copolymerization was carried out in aqueous media. Cerium ammonium nitrate was employed as the initiator in the presence of nitric acid. Acrylic monomers used in the copolymer synthesis were ethyl acrylate (EA) and butyl acrylate (BA). Effects of monomer concentration, initiator concentration, polymerization time, and polymerization temperature on the obtained graft copolymers were investigated. The graft parameters were obtained by thermal gravimetric analysis method. The obtained copolymers (MCC‐g‐PEA, MCC‐g‐PBA) were characterized by attenuated total reflection, wide‐angle X‐ray diffraction, field‐emission electron microscopy, and thermal gravimetric analysis. In comparison to native MCC, better thermal stability of graft copolymers were observed. In addition, the graft copolymers reinforced natural rubber composites were produced, and sulfur was used as the vulcanizing agent. Their vulcanization and mechanical properties were characterized. Comparing to the native MCC reinforced natural rubber composites, the copolymers reinforced natural rubber composites shows improved mechanical properties, indicating the copolymer's potential application as rubber reinforcements. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43087.

Preparation of cellulose graft copolymer based on the combination of ionic liquids and microwave heating

Cellulose is a promising raw material that can be modified through a variety of chemical modifications to obtain many functional materials. Cellulose-g-acrylamide copolymer was prepared in a homogeneous medium by using N,Nʹ-methylenebisacrylamide as the crosslinker without any radical initiator using microwave radiation. The 1-butyl-3-methylimidazolium chloride ionic liquid, which is an environmentally friendly and effective reaction medium, was chosen to dissolve the cellulose and the homogeneous graft polymerisation of acrylamide onto the cellulose. Owing to the effects of microwave heating, the reaction time was significantly shortened: 1 minute microwave heating was adequate, compared to 30 minutes to 5 hours with a conventional heating method. The influences of monomer concentration, crosslinker dosage, microwave power and reaction time were investigated. The obtained cellulose graft copolymer was characterised by infrared spectrum, thermogravimetric analysis and scanning electron microscopy. A feasible reaction mechanism of grafting based on microwave heating was proposed.

Utilization of Poly(Acrylic Acid)/Cellulose Graft Copolymer for Dye and Heavy Metal Removal

A cellulosic component was extracted from low-value palm tree wastes, empty fruit bunches, and functionalized through grafting with acrylic acid in a previous study. The as-synthesized poly(acrylic acid)/cellulose graft copolymer was applied in the current study as an adsorbent for the removal of the cationic dye methylene blue and the heavy metal lead from industrial wastewater. Factors and parameters that govern the adsorption process were studied during the experimental portion of this study. These factors included the effect of agitation duration, adsorbate medium pH, adsorbent dose, adsorbent graft yield, and initial adsorbate concentration on the efficiency of the said adsorption processes. The data obtained from the adsorption of either methylene blue or lead ions onto the graft copolymer were well fitted to both Langmuir and Freundlich adsorption models.

Graft copolymers of hydroxyethyl cellulose by a ‘grafting to’ method:15N labelling as a powerful characterisation tool in ‘click’ polymer chemistry

The use of15N labeling demonstrates the success of ‘grafting to’ preparation of cellulose graft copolymers by ‘click’ coupling.