Synthesis Of Graft Copolymers Research Articles

Synthesis of Novel Acrylamide Graft Copolymer of Acacia nilotica Gum for the Stabilization of Melatonin Nanoparticles for Improved Therapeutic Effect: Optimization Using (3)2 Factorial Design.

The objective of the present study was to optimize the microwave-assisted synthesis of the acrylamide graft copolymer of Acacia nilotica gum (AM-co-ANG). Furthermore, graft copolymer was used for the formulation of a nanoparticulate system using a novel top to bottom solvent antisolvent technique for the delivery of melatonin. Grafting of ANG was optimized by using 32 factorial design, where concentrations of polymer and monomer (acrylamide) were used as independent variables and swelling index in acidic (0.1 N HCl) and basic (1 N NaOH) pH. Grafted polymers were further used to develop and optimize nanoparticulate system using concentration of the graft copolymer and concentration of drug as independent variables. The size of the nanoformulation and entrapment efficiency were selected as dependent variables. Difference in infrared spectrum and absorbance maxima in the ultraviolet region confirm that grafting has taken place. Porous structure and a higher contact angle confirmed hydrophobic nature of AM-co-ANG as compared with the native polymer. Acrylamide graft copolymers show more swelling in 1 N NaOH as compared with 0.1 N HCl. In vitro toxicity studies in hepatic (HepG2 cell line), brain (SHSY5Y cell line), and skin (HaCaT cell line) cells easily predict that synthesized polymer have no cytotoxicity. The entrapment efficiency ranged from 55.24 ± 1.35% to 73.21 ± 1.83%. A nonlinear correlation was observed between independent and dependent variables, as confirmed by multivariate analysis of variance, surface regression, and the correlation report. The prepared formulations were able to release drug up to 12 h. The regression coefficient easily predicted that most of the formulations followed Baker-Lonsdale drug release kinetics.

PTFE-g-GMA graft copolymer synthesis promoted by oxidative gamma-rays method and characterization

AbstractThe functionalization of polymeric matrices through graft polymerization offers various advantages by providing new properties, allowing for additional chemical reactions that the matrix alone could not undergo or that would require drastic chemical conditions to occur. In this work, epoxy groups were incorporated through a graft polymer of poly(glycidyl methacrylate), using a prefunctionalization with peroxide groups in the polytetrafluoroethylene matrix through gamma radiation. These peroxide groups were subsequently used as radical chemical initiators in the graft polymerization reaction of glycidyl methacrylate. The graft polymerization reaction was studied based on the absorbed dose, monomer concentration, reaction time, and temperature. Graphical abstract

Dextran-based nanoparticles with 5-FU-conjugated polymethacrylate segments for drug delivery: Synthesis of amphiphilic graft copolymers by mechanochemical solid-state polymerization and characterization

Dextran (Dx) is a biodegradable and biocompatible polysaccharide, thus promising as a drug delivery carrier for tumor therapy. Herein, we applied mechanical energy to a high molecular weight Dx to control its molecular weight and simultaneously generate mechanoradicals. The solid-state polymerization of methacrylate- or methacrylamide derivatives initiated with Dx mechanoradicals showed polymer conversion of >95%, yielding Dx-based graft copolymers with molecular weights of approximately 30,000 g mol−1. The Dx-based graft copolymers with hydrophobic segments formed nanoparticles with a particle size of 25–35 nm in an aqueous solution. The anti-pancreatic tumor drug 5-fluorouracil (5-FU) was covalently conjugated onto the hydrophobic segments of the amphiphilic Dx, and the nanoparticles were also prepared. The drug release profile from 5-FU-conjugated nanoparticles corresponded well to the Korsmeyer-Peppas model applied to drug release from matrix substrates, and was also immensely predicted by the Logistic and Gompertz curves. The 5-FU-conjugated nanoparticles showed cytotoxicity against the pancreatic adenocarcinoma cell lines (BxPC-3) that were not significantly inferior to the 5-FU positive group. Furthermore, the fluorescein-labeled nanoparticles internalized into BxPC-3 within 6 h and actively migrated into the cytosol. These results suggest that Dx-based graft copolymers with hydrophobic segments might be used to enhance therapeutic activity.

Features of Synthesis of Graft Copolymers of Chitosan and Acrylic Acid

Features of Synthesis of Graft Copolymers of Chitosan and Acrylic Acid

Synthesis and Characterization of Graft Copolymers with Poly(ε-caprolactone) Side Chain Using Hydroxylated Poly(β-myrcene-co-α-methyl styrene).

Graft copolymers have unique application scenarios in the field of high-performance thermoplastic elastomers, resins and rubbers. β-myrcene (My) is a biomass monomer derived from renewable plant resources, and its homopolymer has a low glass transition temperature and high elasticity. In this work, a series of tapered copolymers P(My-co-AMS)k (k = 1, 2, 3) were first synthesized in cyclohexane by one-pot anionic polymerization of My and α-methyl styrene (AMS) using sec-BuLi as the initiator. PAMS chain would fracture when heated at high temperature and could endow the copolymer with thermal degradation property. The effect of the incorporation of AMS unit on the thermal stability and glass transition temperature of polymyrcene main chain was studied. Subsequently, the double bonds in the linear copolymers were partially epoxidized and hydroxylated into hydroxyl groups to obtain hydroxylated copolymer, which was finally used to initiate the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) to synthesize the graft copolymer with PCL as the side chain. All these copolymers before and after modifications were characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), thermogravimetry analysis (TGA), and differential scanning calorimeter (DSC).

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.

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

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.

An orthogonal approach for the synthesis of graft copolymers: Visible light induced free radical polymerization and iniferter processes

Graft copolymers with polystyrene main and poly(ethylene glycol) methyl ether acrylate side chains are synthesized via an orthogonal approach combining visible light induced free radical polymerization and iniferter processes. The method relies on a deliberately designed, double functional monomer, 2,2,2-(triphenylethyl)styrene (TPES), containing both polymerizable and iniferter units.

Synthesis of tragacanth gum-based programmable adhesive for wood binding applications

Synthesis of graft copolymer [2-(methacryloyloxy) ethyl]trimethylammonium chloride (MAETMAC) grafted gum tragacanth was performed using the microwave-assisted technique using potassium persulfate (KPS) as a free radical initiator. The synthesized grades were optimized by varying the monomer and the initiator concentration. The intended grafting was ascertained through standard physico-chemical characterizations. The synthesized graft copolymer was studied as a water-soluble adhesive for fabrication of single lap joint. The failure shear stress of lap joint was obtained using the Universal Testing Machine (UTM). Further, the self-separation study of the lap joints was carried out by soaking the lap-joint under water until they got self-separated. The failure shear stress and self-separation time of the adhesive in water were compared with three commercial adhesives available. The properties “self separation time” in water and “failure shear stress” were programmable at the molecular level (molecular level programming) in terms of percentage grafting.

Green synthesis of cellulose graft copolymers for anion exchange water purification

Green synthesis of cellulose graft copolymers for anion exchange water purification

Synthesis and catalytic performance of wood cellulose nanofibers grafted with polylactic acid in rare-earth complexes based on tetrazole carboxylic acids

Stannous octanoate [Sn(Oct)2] and 4-dimethylamino pyridine (DMAP) were used to catalyze the synthesis of amphiphilic cellulose-based graft copolymers, but the acute toxicity of tin ions and DMAP prompts the need for the application of less harmful catalysts. Herein, green catalyst complexes 1–3 [M(H0.5L)2(H2O)5]·2(H2O) (M = Sm, 1; M = Nd, 2; M = Eu, 3; H2L = 4-(3-(tetrazol-5-yl)pyridin-5-yl)benzoic acid) were synthesized, and their properties were systematically investigated. Single-crystal X-ray diffraction showed that the complexes possessed a zero-dimensional structure, while the thermogravimetry and scanning electron microscopy results confirmed their stability after heating at 110 °C for 10 h. Using complexes 1–3 and DMAP as the catalysts, CNFs were grafted with l-lactide via homogeneous ring-opening polymerization to form wood cellulose nanofibers grafted with l-lactide (WGLAs), and the effects of the ratio of wood cellulose nanofibers (WCNFs) to l-lactide ([AGU]/[LA]) and catalyst dosage were studied. The polymerization followed the coordination–insertion mechanism. Under comparable reaction conditions, the grafting ratio of WGLA-1 reached 84.7 %, and the grafting ratio of complex 1 was found to be higher than those achieved using DMAP. WGLAs demonstrated good thermal stability without cytotoxicity, and the residual catalysts in the WGLAs exhibited fluorescence characteristics. Overall, amphiphilic cellulose-based materials with fluorescence emission offered a promising modification strategy to prepare high-performance polymer composites for agriculture and biomedical application.

Semiconducting Polymer Nanoporous Thin Films as a Tool to Regulate Intracellular ROS Balance in Endothelial Cells.

The design of soft and nanometer-scale photoelectrodes able to stimulate and promote the intracellular concentration of reactive oxygen species (ROS) is searched for redox medicine applications. In this work, we show semiconducting polymer porous thin films with an enhanced photoelectrochemical generation of ROS in human umbilical vein endothelial cells (HUVECs). To achieve that aim, we synthesized graft copolymers, made of poly(3-hexylthiophene) (P3HT) and degradable poly(lactic acid) (PLA) segments, P3HT-g-PLA. In a second step, the hydrolysis of sacrificial PLA leads to nanometer-scale porous P3HT thin films. The pore sizes in the nm regime (220-1200 nm) were controlled by the copolymer composition and the structural arrangement of the copolymers during the film formation, as determined by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The porous P3HT thin films showed enhanced photofaradaic behavior, generating a higher concentration of ROS in comparison to non-porous P3HT films, as determined by scanning electrochemical microscopy (SECM) measurements. The exogenous ROS production was able to modulate the intracellular ROS concentration in HUVECs at non-toxic levels, thus affecting the physiological functions of cells. Results presented in this work provide an important step forward in the development of new tools for precise, on-demand, and non-invasive modulation of intracellular ROS species and may be potentially extended to many other physiological or pathological cell models.

Synthesis and characterization of a brush type graft copolymer via RAFT and "click" chemistry methods

Synthesis and characterization of a brush type graft copolymer via RAFT and "click" chemistry methods

Copper oxide nanocomposite particles supported on sodium alginate-g-polyallylamine based reduced graphene oxide: An efficient electrochemical sensor for sensitive detection of cadmium ions in water

A highly sensitive and selective electrochemical sensor, sodium alginate-g-polyallylamine/reducedgrapheneoxide/CuO nanocomposite particles (SAGPMRGO@CuO NPs) has been synthesized for the detection of Cd2+ ions in the aqueous environment. The graft copolymer/reduced graphene oxide supported CuO nanocomposite particles are prepared through bioreduction of graphene oxide by a novel synthesized graft copolymer sodium alginate-g-PAAM (SAG-g-PAAM) to reduced graphene oxide (SAGPMRGO) followed by using it as both a reductant and a stabilizing agent to obtain SAGPMRGO@CuO hybrid nanocomposite particles. The graft copolymer is prepared via free radical solution phase graft copolymerization technique. The graphene oxide (GO) is prepared by the oxidation of graphite using modified Hummer's method. The prepared nanocomposite particles are characterized by UV-VIS, FTIR and Raman spectroscopy, powder X-ray diffraction (PXRD), HRTEM-EDS, FESEM, XPS and DLS analysis with zeta potential measurement in colloidal suspension. The prepared graft copolymer is characterized by 1H and 13C NMR spectroscopy, PXRD and FESEM analysis and the SAMPGRGO is characterized by UV-VIS and Raman spectroscopy, PXRD and FESEM analysis. The CuO nanocomposite particles are spindle shaped with an average particle size ranges from 15.6 nm to 32.1 nm and are well polydispersed. Metal ion (Cd2+) sensing is carried out by cyclic voltammetry (CV) and chronoamperometry (CA) analysis under optimum conditions. The limit of detection (LOD) and limit of quantitation (LOQ) is found to be 1.27 nM and 4.24 nM respectively which is lower than some other reported works. The reproducibility and stability properties of the developed sensor are examined where the results are found to be satisfactory. The selective detection of Cd2+ ions in a river water sample is also evaluated with an excellent performance.

Grafting of Poly (Acrylic Acid) onto Cassia fistula Seed Gum: Synthesis, Optimization, and Characterization

Aim: This study aimed to synthesize a natural polysaccharide-based semisynthetic mucoadhesive and sustained-release copolymer. 
 Background: Natural polysaccharides have been preferred as drug carriers because of their abundance, easy availability, low cost, biocompatibility, biodegradability, and physiochemical compatibility. But sometimes they need to be chemically functionalized in order to impart some physiochemical properties for the customization of drug delivery.
 Objective: The objective was to graft poly (sodium acrylate) onto Cassia fistula seed gum and the characterizations of the derived copolymer.
 Method: CFSG-grafted-poly (sodium acrylate) (CFSG-g-PSA) was synthesized by microwave-assisted free-radical initiation method using ceric ammonium nitrate (CAN) as a free-radical initiator. The concentration of acrylic acid (AA), ceric ammonium nitrate (CAN), and microwave-irradiation time (MW) were taken as independent synthetic variables. Synthesis was designed by 23 full factorial designs with two levels of each variable. %grafting, % grafting efficiency and % conversion was taken as response variables. ANOVA and numerical optimization were done using Design-Expert Software (version 11.0) to obtain the optimized synthetic condition. The copolymer was characterized by elemental analysis, FTIR, NMR, viscosity, DSC, TGA-DTA, PXRD, SEM, water-uptake, and biodegradation study.
 Results: Elemental analysis, FTIR, and NMR study ratified the formation of the copolymer. The highest % of grafting was found to be 790% in this study. The combination of microwave irradiation and CAN have shown a synergistic effect on % grafting and % grafting efficiency. Software-based numerical optimization finds the S1 batch as the best synthetic batch (790%G) with 10 g AA, 0.5 g CAN, and 1 min MW. The study also exhibits the biodegradation nature of the copolymer in a simulated colonic environment.
 Conclusion: The study demonstrates the synthesis of graft-copolymer by simple, easy, rapid, and one-pot method without the use of any sophisticated instrument and nitrogen environment.

Synthesis and Characterization of Functional Cellulose–Ether-Based PCL- and PLA-Grafts-Copolymers

The use of biodegradable materials such as cellulose and polyesters can be extended through the combination, as well as modification, of these biopolymers. By controlling the molecular structure and composition of copolymers of these components, it should also be possible to tailor their material properties. We hereby report on the synthesis and characterization of cellulose-based graft copolymers with a precise molecular composition and copolymer architecture. To prepare such materials, we initially modified cellulose through the regioselective protection of the 6-OH group using trityl chloride. The 6-O protected compound was then alkylated, and deprotection at the 6-OH group provided the desired 2,3-di-O-alkyl cellulose compounds that were used as macroinitiators for ring opening polymerization. Regioselective modification was hereby necessary to obtain compounds with an exact molecular composition. Ring opening polymerization, catalyzed by Sn(Oct)2, at the primary 6-OH group of the cellulose macroinitiator, using L-lactide or ε-caprolactone, resulted in graft copolymers with the desired functionalization pattern. The materials were characterized using Fourier-transform infrared spectroscopy, 1H- and 13C- nuclear magnetic resonance spectroscopy, size exclusion chromatography as well as X-ray diffraction, and differential scanning calorimetry. PCL-based copolymers exhibited distinct melting point as well as a crystalline phase of up to 47%, while copolymers with PLA segments were highly amorphous, showing a broad amorphous reflex in the XRD spectra, and no melting or crystallization points were discernible using differential scanning calorimetry.

Synthesis and degradation study of graft copolymers of poly(limonene carbonate)

Polyester-grafted poly(limonene carbonate) with improved hydrophilicity, elastic behavior, and degradation under enzymatic and wastewater conditions is presented.

Synthesis of a graft copolymer of chloroprene rubber with acrylic acid as a shoe adhesive

Synthesized graft copolymers of chloroprene rubber with acrylic acid. A mixture of benzene and dimethylformamide was used as a solvent, and potassium persulfate was used as a polymerization initiator. Based on the dependence of the copolymerization rate on the concentrations of components and temperature, the order of the reaction rate in terms of the concentration of acrylic acid (2.0), potassium persulfate (1.2) and the activation energy of the process (24.4 kJ/mole) were determined. The degree of grafting of polyacrylic acid increases from 2% to 140% with increasing process time, monomer and initiator concentrations. Grafting efficiency is high (70-90%) in a wide range of time and component concentrations. The graft copolymer has high adhesion to the surface of the skin and tissue.

Pendant Group Modifications Provide Graft Copolymer Silicones with Exceptionally Broad Thermomechanical Properties.

Graft copolymers offer a versatile platform for the design of self-assembling materials; however, simple strategies for precisely and independently controlling the thermomechanical and morphological properties of graft copolymers remain elusive. Here, using a library of 92 polynorbornene-graft-polydimethylsiloxane (PDMS) copolymers, we discover a versatile backbone-pendant sequence-control strategy that addresses this challenge. Small structural variations of pendant groups, e.g., cyclohexyl versus n-hexyl, of small-molecule comonomers have dramatic impacts on order-to-disorder transitions, glass transitions, mechanical properties, and morphologies of statistical and block silicone-based graft copolymers, providing an exceptionally broad palette of designable materials properties. For example, statistical graft copolymers with high PDMS volume fractions yielded unbridged body-centered cubic morphologies that behaved as soft plastic crystals. By contrast, lamellae-forming graft copolymers provided robust, yet reprocessable silicone thermoplastics (TPs) with transition temperatures spanning over 160 °C and elastic moduli as high as 150 MPa despite being both unentangled and un-cross-linked. Altogether, this study reveals a new pendant-group-mediated self-assembly strategy that simplifies graft copolymer synthesis and enables access to a diverse family of silicone-based materials, setting the stage for the broader development of self-assembling materials with tailored performance specifications.