Graft Copolymers Research Articles

GREEN ADSORBENT SYNTHESIS FROMORANGE MESOCARP CELLULOSE USING GRAFT COPOLYMERIZATION

The potential of agricultural waste like orange (Citrus sinensis) mesocarp is yet to be explored. Thus, in this study the extractionof green adsorbent that will be renewable, low cost and environmentally friendly from orange mesocarp was examined. The extraction was done using alkali pretreatment method followed by bleaching process to obtain cellulose and dissolvethe hemicellulose, lignin and other extractives. Then, graft copolymerisation of acrylamide onto the cellulose obtainedwas done usingfree radical initiation system. Grafting parameterswere studied by varying the effects of initiator concentrations,monomer to cellulose ratio, temperature and time. Distilled water was used toextract the formedpolyacrylamide (PAam)for 48 hours. And the characterization of the extracted and grafted cellulose samples was carried out by Fourier Transform Infrared Spectroscopy(FTIR).Orange mesocarp gave a cellulose average yield of 29.1%. The optimum grafting conditions were found to be 30OC at a time interval of 2 hours, ratio of monomer to cellulose being 3:1 and initiator concentration of 0.020M. The percentages of polymerization, graft and graft efficiency were 113.40, 86.83 and 45.90respectively. Also, the absorbance peaks of thesamplesconfirmed that grafting was effectively carried out on the cellulose backbone.

Oil absorbent based on lauryl methacrylate grafting onto cellulose of water hyacinth (Eichhornia crassipes)

AbstractIn this article, a novel oil‐absorbent polymer was synthesized by graft polymerization of lauryl methacrylate (LMA) onto water hyacinth (WH) using 2,2′‐azobisisobutyronitrile (AIBN) as initiator and divinyl benzene (DVB) as a crosslinking agent. The effects of initiator content, LMA content, reaction temperature, reaction time, and crosslinker content on the superabsorbent polymer were investigated. The prepared graft copolymer WH‐g‐LMA was analyzed using FTIR, SEM, XRD, and TGA. In the presence of the better cross‐linker DVB (1.5%) and contact time of about 25 min, the maximal Q (oil sorption capacity) of co‐polymer towards crude and Soybean oils is 23.68 and 25.72 g g−1, respectively. The Q is reduced when sorbent dosage increased, but it increases with increasing the temperature and reaches a maximum of 40 °C. The reusability of co‐polymer is characteristic of 7 sorption/desorption cycles.

Toughening poly(lactic acid) with novel polyolefin-graft-poly(lactic acid) copolymers maintaining high transparency and stiffness

The combination of well-balanced mechanical performance, high transparency and appealing eco-friendly attributes endows poly(lactic acid) (PLA) with significantly potential for wide-ranging applications in high-value packaging sectors. However, effectively toughening PLA without compromising its transparency and stiffness remains a formidable challenge. In this study, we synthesized a series of graft copolymers by incorporating hydroxyl-functionalized linear low density polyethylene (LLDPEOH) and copolymers of cycloolefin (COCOH) as the main chain and PLA as the side chain, which were subsequently employed as novel toughening agents for commercial PLA. The achievement of high-performance PLA blends with a balanced combination of toughness, strength, and transparency can be realized through meticulous tuning of the structure and mass fraction of the blended graft copolymers. The maximum elongation at break for the PLA blends increased by about 50 times that of neat PLA, reaching up to 300 %. Furthermore, these materials retained their high strength (54 MPa) and excellent transparency (light transmittance up to 90 %). The excellent properties of PLA blends could be ascribed to the well-designed chain structure of the graft copolymer which leaded to and excellent compatibility with the PLA matrix and unique phase morphology. This work is significant in guiding the design and synthesis of graft copolymers as toughening agents for PLA, thereby expanding its application range in areas where high transparency and toughness are required.

A Review on Self-Assembly Driven Optoelectronic Properties of Polythiophene-Peptide and Polythiophene-Polymer Conjugates.

Polythiophene (PT) is an important conducting polymer for its outstanding optoelectronic properties. Here, we delineate the self-assembly-driven optoelectronic properties of PT-peptide and PT-polymer conjugates, taking examples from recent literature reports. PT-peptide conjugates made by both covalent and noncovalent approaches are discussed. Poly(3-thiophene acetic acid) (P3TAA) covalently coupled with Gly-Gly-His tripeptide, C-protected and deprotected tripeptide H2N-F-F-V-OMe, etc. exhibits self-assembly-driven absorbance, fluorescence, photocurrent, and electronic properties. Noncovalent PT-peptide conjugates produced via ionic, H-bonding, and π-stacking interactions show tunable morphology and optoelectronic properties by varying the composition of a component. PT conjugated with Alzheimer's disease peptide (KLVFFAE, Aβ16-22) shows enhanced photocatalytic water splitting, cationic PT(CPT-I)-perylene bisimide-appended dipeptide (PBI-DY), and anionic PT-perylene diimide-appended cationic peptide (PBI-NH3+) conjugates and exhibits self-assembly-driven enhanced photoswitching and organic mixed electronic and ionic conductivity (OMEIC) properties. In the PT-polymer conjugates, self-assembly-driven optoelectronic properties of covalently produced PT-random copolymers, PT-block copolymers, PT-graft-random copolymers, and PT-graft-block copolymer conjugates are discussed. The HOMO-LUMO levels of hyperbranched polymers are optimized to obtain better power conversion efficiency (PCE) in the bulk heterojunction (BHJ) solar cell than in linear polymers, and P3TAA-ran-P3HT (43 mol % P3TAA) conjugated with MAPbI3 perovskite exhibits higher PCE (10%) than that with only P3TAA hole-transporting material. In the ampholytic polythiophene (APT), on increasing pH, the morphology changes from the vesicle to fibrillar network for the dethreading of the PT chain, resulting in a red shift of the absorbance peak, an enormous increase in PL intensity, lowering of the charge transfer resistance, and an induction of Warburg impedance for the release of quencher I- ions. The PT-g-(PDMAEMA-co-PGLU-HEM) graft copolymer self-assembles with Con-A lectin, causing fluorescence quenching, and acts as a sensor for Con-A with a LOD of 57 mg/L. Varying sequences of the block copolymer containing pH-responsive PDMAEMA and temperature-responsive PDEGMEM grafted to the PT backbone shows different self-assembly, optical, electronic, and photocurrent properties depending on the proximity and preponderance of the block sequence on the PT backbone.

Synthesis and assessment of novel cationic graft copolymer as flocculant for sugarcane juice

Synthesis and assessment of novel cationic graft copolymer as flocculant for sugarcane juice

Effect of chain structures of monomer on hydroxyethyl cellulose-based superabsorbent properties and improvement of chickpeas plant growth of water deficit-stressed

The aim of this research was evaluation of the influence of distance between zwitterionic monomer ions on the performance of superabsorbents. For this purpose, two zwitterionic monomers 4-(3-aminopropyl) amino-4-oxo-2-butenoic acid (APOB) and 4-(6-aminohexyl) amino-4-oxo-2-butenoic acid (AHOB) were prepared and applied for synthesis of two new superabsorbents through graft copolymerization onto hydroxyethyl cellulose (HEC) in the presence of acrylic acid (AA). In synthesis of superabsorbents factors such as the highest water absorbency capacity, absorbency rate, gel strength, and environmental problems should be resolved or improved. The results demonstrated that the water absorbency capacity and rate parameters (τ) of HEC-g-p(AA-co-APOB) and HEC-g-p(AA-co-AHOB) in distilled water were 986.62, 664.38 g/g, and 98.04, 140.84 min, respectively. The biodegradability of HEC-g-p(AA-co-APOB) was approximately 4 times more than HEC-g-p(AA-co-AHOB). However, based on the rheological analyses (G'/G″) HEC-g-p(AA-co-AHOB) was stronger than the other. Additionally, studies of water retention on soil containing HEC-g-p(AA-co-AHOB) superabsorbent (soil with 0.25 wt% material) showed that the after 30 days has ≤5 % water while soil in the absence of superabsorbent after 10 days completely dried. Studies of the growth of plants in soil demonstrated in the presence of HEC-g-p(AA-co-AHOB) the average length of shoots was 36 cm while without superabsorbent were 25 cm.

Copolymers of Gelatin-graft-poly(3-hexylthiophene) for Transient Electronics.

As transient electronics continue to advance, the demand for new materials has given rise to the exploration of conducting polymer (CP)-based electronic materials. The big challenge lies in balancing conductivity while introducing controlled degradable properties into CP-based transient materials. In response to this, we present in this work a concept of using conducting polymers attached to an enzymatically biodegradable biopolymer to create transient polymer electronics materials. Specifically, poly(3-hexyl thiophene) (P3HT) is covalently grafted onto biopolymer gelatin, affording graft copolymer gelatin-graft-poly(3-hexyl thiophene) (termed Gel-g-P3HT). The thin films of Gel-g-P3HT that were produced by optimized processing solvent (THF/H2O cosolvent) showed enhanced π-π stacking domains of P3HT, resulting in semiconducting thin films with good electroactivity. Due to the presence of amide bonds in the gelatin backbone, Gel-g-P3HT underwent degradation over a period of 5 days, resulting in the formation of amphiphilic micellar nanoparticles that are biocompatible and nontoxic. The potential of these conductive and degradable graft copolymers was demonstrated in a pressure sensor. This research paves the way for developing biocompatible and enzymatically degradable polymer materials based on P3HT, enabling the next generation of transient polymer electronics for diverse applications, such as skin, implantable, and environmental electronics.

Manipulation of Macrophage Uptake by Controlling the Aspect Ratio of Graft Copolymer Micelles.

Nanostructures of drug carriers play a crucial role in nanomedicine due to their ability to influence drug delivery. There is yet no clear consensus regarding the optimal size and shape (e.g., aspect ratio) of nanoparticles for minimizing macrophage uptake, given the difficulties in controlling the shape and size of nanoparticles while maintaining identical surface properties. Here, we employed graft copolymer self-assembly to prepare polymer micelles with aspect ratios ranging from 1.0 (spherical) to 10.8 (cylindrical) and closely matched interfacial properties. Notably, our findings emphasize that cylindrical micelles with an aspect ratio of 2.4 are the least susceptible to macrophage uptake compared with both their longer counterparts and spherical micelles. This reduced uptake of the short cylindrical micelles results in a 3.3-fold increase in blood circulation time compared with their spherical counterparts. Controlling the aspect ratio of nanoparticles is crucial for improving drug delivery efficacy through better nanoparticle design.

Hierarchical spontaneous self-assembly of polyethylenimine-poly(propylene glycol) copolymer into cationic polyelectrolyte pH-responsive thermogel

Temperature-responsive hydrogels, otherwise known as thermogels, are promising biomaterials which undergo phase change from liquid to a solid-like gel state when warmed. Although poly (ethylene glycol) (PEG) is employed extensively as the hydrophilic segment in thermogelling polymer design, recent years has witnessed development of new families of PEG-free thermogelling copolymers which offer new opportunities in expanding material property profiles for new biomedical applications. Herein, we study the supramolecular self-assembly process of PEG-free amphiphilic branched graft copolymer containing polyethylenimine (PEI) and poly (propylene glycol) (PPG), which shows both thermogelling ability and pH-responsive gelation behaviour. Additionally, we demonstrate the ease of post-synthetic modulation of thermogel properties by amine functionalisation on the PEI copolymer segments through convenient nucleophilic substitution and amide formation reactions. The synthetic platform offered by PEI-PPG thermogels allow facile customisation of these versatile materials for targeted biomedical applications.

Antimicrobial, Probiotic, and Immunomodulatory Potential of Cannabis sativa Extract and Delivery Systems.

The compounds present in hemp show multidirectional biological activity. It is related to the presence of secondary metabolites, mainly cannabinoids, terpenes, and flavonoids, and the synergy of their biological activity. The aim of this study was to assess the activity of the Henola Cannabis sativae extract and its combinations with selected carriers (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer, magnesium aluminometasilicate, and hydroxypropyl-β-cyclodextrin) in terms of antimicrobial, probiotic, and immunobiological effects. As a result of the conducted research, the antimicrobial activity of the extract was confirmed in relation to the following microorganisms: Clostridium difficile, Listeria monocytogenes, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus pyrogenes, Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium, Pseudomonas aereuginosa, and Candida albicans (microorganism count was reduced from ~102 CFU mL-1 to <10 CFU mL-1 in most cases). Additionally, for the system with hydroxypropyl-β-cyclodextrin, a significant probiotic potential against bacterial strains was established for strains Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus rhamnosus, Lactobacillus reuteri, Pediococcus pentosaceus, Lactococcus lactis, Lactobacillus fermentum, and Streptococcus thermophilus (microorganism count was increased from ~102 to 104-107). In terms of immunomodulatory properties, it was determined that the tested extract and the systems caused changes in IL-6, IL-8, and TNF-α levels.

Inkjet printed acrylate-urethane modified poly(3,4-ethylenedioxythiophene) flexible conductive films

Abstract Flexible electronics is a new generation of electronic devices in which electronic components are integrated into flexible substrates. It is used in the fabrication of displays, solar cells, integrated circuits, and increasingly in the fabrication of electronic skin (E-skin), which can mimic the properties of human skin by being able to follow skin movements and flexures without loss of mechanical and electrical properties. E-skin is suitable for integrating various sensors to monitor personal health. Conductive polymers are used in flexible electronics due to their electrical conductivity, low mass, and stability. However, their main disadvantage is their brittleness, which is why they don’t possess flexibility property without modification. Therefore, in this work, the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) was used as the main chain and the side branches of poly(acrylate-urethane) (PAU) were grafted onto it by atom transfer radical polymerization (ATRP) onto it, obtaining the grafted copolymer PEDOT-g-PAU. In this way, the main chain of PEDOT retains the property of electrical conductivity without losing conjugation, while the side branches of PAU have the ability to crosslink non-covalently through hydrogen bonds with PAU side branches of adjacent polymer molecules due to the presence of oxygen in their structure. The presence of hydrogen bonds allows increasing the stretchability and flexibility of the material, and they also have the ability to spontaneously renew themselves when they break due to excessive stress. Three different synthesis conditions were used to obtain polymers of different structure, which were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and measurement of electrical conductivity with a four-point probe (4PP) method. The obtained graft copolymer was prepared in the form of ink and printed on a polyurethane (PU) substrate using inkjet technique. The conductivity of the printed layer, its elongation and adhesion were investigated, while possible delamination of the printed polymer layer was also monitored. The results showed that the PEDOT-g-PAU copolymer was successfully synthesized and inkjet printing on PU film was successful. The obtained material has satisfactory electrical and mechanical properties and could be used for the integration of fully functional biosensors with further optimization of the composition.

Design of Silk Fabric Surface with Enhanced Antiseptic Properties through Graft Modification and Iodophor Integration

AbstractTo improve the hydrophobic character of silk and impart iodine complex ion adsorption, the surface of woven silk fabric is enriched by different functional groups through the grafting of N‐vinylpyrrolidone (NVP), ethylene glycol dimethacrylate (EGDMA), and their mixtures (NVP–EGDMA). The dominant fibrous texture of silk enables an efficient graft copolymerization in terms of high grafting yield (&gt;30%) after applying a mild degumming process. The structural and morphological alterations in the silk surface are evidenced with attenuated total reflectance‐fourier transform infrared spectroscopy (ATR‐FTIR), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. The imparted hydrophilicity property of the samples is revealed by contact angle–wetting time measurements. The usability of the graft‐modified samples as an iodophor polymeric substrate is then examined by treatment with I2/KI solutions, and the results are monitored using UV–vis spectroscopy. It is obtained that the NVP–EGDMA mixture‐grafted sample exhibits satisfactorily high iodine adsorption compared to untreated and NVP‐grafted silk samples, such as 0.05 g per 1 g fabric with high antibacterial activity against various pathogens, including methicillin‐resistant Staphylococcus aureus (MRSA) responsible for hospital‐acquired infections. This finding evidences its potential as an alternative antiseptic tissue for biomedical applications.

Study of the high-energy alpha particles influence on the styrene accumulation kinetics and functional groups during the synthesis of proton-exchange membranes based on PVDF.

The study investigates the effect of alpha irradiation on the graft copolymerization of styrene with polyvinylidene fluoride (PVDF). Using methods of radiation-chemical modification, a proton exchange membrane (PEM) with a uniform distribution of functional sulfate groups throughout the entire volume was developed. Grafting of styrene was carried out at different temperatures and solution concentrations. Functional sulfo-groups were added to the graft polymer by sulfonation, with the addition of solvents. The degree of grafting (DG), water absorption (W) and exchange capacity (IEC) correlate well with the absorbed dose and alpha particle fluence. Research into this method will allow us to develop an affordable industrial technology for widespread implementation.

Supramolecular Synthesis of Star Polymers.

Invited for this month's cover are the collaborating groups of Prof. Dr Takeharu Haino at Hiroshima University (Japan) and Dr Natsumi Nitta at the University of Chicago (USA). The cover picture shows cartoons of miktoarm A8Bn star and graft copolymers formed by molecular recognition of a self-assembled capsule possessing eight polymer chains and guest-terminated and guest-centered polymers. Read the full text of the review at 10.1002/cplu.20240014.

Fabrication of cellulose-collagen based biosorbent as eco-friendly scavengers for uranyl ions

The aim of the present research is to fabricate a biosorbent using agricultural waste for removal of uranium from contaminated water i.e. “waste to wealth” approach. Cellulose extracted from wheat straw was mercerized and a novel semi-interpenetrating polymer network (semi-IPN) was fabricated through graft copolymerization of polyvinyl alcohol onto hybrid mercerized cellulose + collagen backbone. Response surface methodology was used for optimization of different reaction parameters as a function of % grafting (195.1 %) was carried out. Semi-IPN was found to possess higher thermal stability. Adsorption results revealed that the optimum parameters for the elimination of uranium using semi-IPN were: adsorbent dose = 0.15 g, pH = 6.0, contact time = 120 min and initial U (VI) concentration = 100 μg/L. The pseudo-second-order kinetic model gave the best description of the adsorption equilibrium data as the calculated qe value is nearest to the experimental qe for the different initial U(VI) concentrations. Adsorption experiments followed Langmuir isotherm with R2 = 0.999. Furthermore, recyclability and reusability studies showed that the adsorption efficiency of semi-IPN was 82 % after 5 cycles indicating the superior recycling execution of fabricated biosorbent. Thus, the fabricated ecofriendly device can be used effectively for the removal of uranium from contaminated wastewater sources.

Fabrication of modified lignin-based liquid mulching film and its potential application

Abstract Liquid mulching film is an emerging film material to replace the traditional plastic film, which causes wide public concern. In this study, a graft copolymer (LS-AA) was synthesized from sodium lignosulfonate (LS) by free radical polymerization, which was added as enhancer to the cationic starch (CS) solutions to obtain the CLA based film. The grafting conditions was optimized by response surface methodology (RSM) for the preparation of LS-AA, after that the LS-AA was characterized by FTIR, XRD, and TG. The highest grafting rate was obtained under the reaction conditions of 80 °C for 2.6 h with the mass ratio of monomer and LS of 5.5/5 at initiator dosage of 1 %. The fabricated liquid mulching film with addition of LS-AA showed outstanding anti-ultraviolet, biodegradation, anti-erosion, which provided theoretical base and practical references for popularizing and application of liquid mulching film in the dust prevention and sand fixation.

Hybrid Banana Pseudo Stem biochar- poly (N-hydroxyethylacrylamide) hydrogel and its magnetic nanocomposite for effective remediation of dye from wastewater

A hybrid hydrogel based on Banana Pseudo Stem, an agricultural waste material, has been developed as an adsorbent for use in wastewater treatment. The Biochar obtained from Banana Pseudo Stem was modified by graft copolymerization with N-hydroxyethylacrylamide (HEAAm). The graft copolymer was made by microwave irradiation of an aqueous mixture containing BPSBC, N-hydroxyethylacrylamide (HEAAm), N,N-methylenebisacrylamide (MBA), and potassium peroxodisulphate (KPS). The magnetite (Fe3O4) nanoparticles have been incorporated into the gel by in-situ diffusion of Fe2+ and Fe3+ followed by a reaction with ammonia solution. FTIR, SEM, EDS, TGA, VSM, BET, and XRD techniques were used to characterize the gel and its nanocomposite. The swelling process appeared to be a second-order kinetic process and the mechanism of water transport is found to be non-Fickian. The hybrid gel and nanocomposite were evaluated for the adsorptive removal of cationic dyes using Methylene Blue (MB) and Crystal Violet (CV) as model dyes. The adsorption capacities of the graft copolymer gel for MB and CV were 200 mg g−1 and 183 mg g−1 respectively. A considerable increase in adsorption capacities was observed in nanocomposite formation, with adsorption capacity values of 235 and 202 mg g−1 for MB and CV respectively. The pseudo-second-order kinetic model and Freundlich adsorption isotherm model provide the best fit of the dye sorption data. Thermodynamic studies revealed adsorption to be a spontaneous and endothermic process. Effective desorption under acidic conditions illustrated the possibility of reuse of the developed adsorbent materials in repeated cycles during the wastewater treatment process.

The Radiation Graft Copolymerization of Allylmethacrylate to Polyvinylidene Fluoride to Prepare of Membrane and Its Affordability for Domestic Wastewater Treatment

The Radiation Graft Copolymerization of Allylmethacrylate to Polyvinylidene Fluoride to Prepare of Membrane and Its Affordability for Domestic Wastewater Treatment

QbD Assisted Optimization of Microwave-assisted Synthesis of Polyacrylamide Grafted Tragacanth: Characterization and Instrumental Analysis

Background: Polysaccharides have recently attracted a lot of attention in the designing of drug delivery systems due to their wide availability, lack of toxicity, and numerous ways that their nature, structure, and functionality can be altered. Methods: Microwave-assisted synthesis of graft copolymer of tragacanth (TRA) is done with poly-acrylamide (PAM) by free radical polymerization using ceric ammonium nitrate (CAN) as initiator. Grafting polymer concentration, CAN concentration, and exposure time were selected as independent variables, and their effect is studied for Grafting Efficiency (GE) and Intrinsic viscosity (IV) using Box-Behnken optimization design. Results: A quadratic model was suggested by the software for further statistical evaluation. On the basis of the desirability approach, optimized parameters for microwave-assisted synthesis were demon-strated, and further grafted TRA (Gr-TRA) was synthesized. Gr-TRA was studied for various charac-terization and elemental analysis. Gr-TRA showed the highest swelling index and least weight loss during the chemical resistance test. Further instrumental analyses like FTIR, XRD, and elemental anal-ysis confirmed the formation of Gr-TRA. Conclusion: Based on all of the above findings, the synthesis of PAM-grafted TRA has been optimized and could be used as a new pharmaceutical excipient in designing different dosage forms.

Lignin phenolation by graft copolymerization to boost its reactivity

Lignin is the most abundant phenolic biopolymer and a renewable resource of aromatics. It can be used as a phenol substitute in the synthesis of phenolic resins. However, lignin is not as reactive as phenol, so phenolation is generally carried out to improve lignin reactivity. In this work, we suggest a solution to circumvent the limitations of traditional phenolation (e.g., high temperature, strong acids/bases, limited reactivity, and phenol toxicity). We first attempt new lignin phenolation by graft copolymerization in which polymeric phenol, instead of toxic phenol, is introduced to lignin. Organosolv lignin from hardwood was modified with 2-bromoisobutyryl bromide to act as a lignin macroinitiator (L-Br). A protected phenolic monomer, 4-acetoxystyrene, was graft copolymerized onto L-Br using CuBr2/tris[2-(dimethylamino)ethyl]amine as a catalyst/ligand, after which the resultant lignin copolymer was deacetylated to produce lignin grafted with poly(4-hydroxystyrene). This poly-phenolation process was conducted at room temperature without the strong acids/bases and toxic phenol required in conventional phenolation. The poly-phenolated lignin was analyzed using 1H-, 13C-, and 31P NMR spectroscopy and gel permeation chromatography. This novel phenolation process enhanced the reactive sites of lignin more than tenfold. It also reduced the dark color of technical lignins significantly, thereby overcoming a serious obstacle to their applicability.