Copolymerization Reaction Research Articles

IUPAC recommended experimental methods and data evaluation procedures for the determination of radical copolymerization reactivity ratios from composition data

The IUPAC method uses monomer composition, conversion, and copolymer composition to find reactivity ratios. Shown the optimal reactivity ratios in red and a 95% Confidence Interval in blue.

Functionalized magnetic chitosan-based adsorbent for efficient tetracycline removal: Deep investigation of adsorption behaviors and mechanisms

As removal performance of tetracyclines in traditional wastewater treatment plants cannot satisfy the increasingly strict discharge requirements, developing an efficient approach to overcome this problem is quite urgent. Herein, a novel functionalized magnetic chitosan-based adsorbent (Fe3O4@CAA) with core-shell structure and unique magnetic responsiveness was facilely prepared by ultrasound-initiated radical grafting copolymerization and cross-link reaction. The as-prepared Fe3O4@CAA was fully characterized with TEM, SEM, BET, FTIR, TGA, XRD, VSM, and served as an efficient adsorbent for tetracycline hydrochloride (TCH) removal. Adsorption behaviors of TCH by Fe3O4@CAA were deeply evaluated at different adsorption time, initial TCH concentration, reaction temperature, solution pH, and background pollutant concentration. Results showed that Fe3O4@CAA presented a more competitive adsorption capacity of 325.04 mg g−1 compared with Fe3O4@CS and other reported adsorbent, due to the introduction of more active adsorption sites by abundant functional groups, including amino groups, hydroxyl groups, and sulfonic acid groups. After saturated adsorption, TCH loaded Fe3O4@CAA was easily collected by magnetic separation, and recycled after acid pickling. Fe3O4@CAA was successfully reused in five adsorption-desorption cycles, without obvious adsorption capacity loss. In binary pollutant systems, inorganic cations and Pb(II) restrained TCH adsorption by competitive effect, while proper amount of Cu(II) promoted TCH adsorption by bridge effect. FTIR and XPS analyses revealed that the adsorption mechanism of TCH by Fe3O4@CAA mainly included electrostatic interaction and hydrogen bonding, and Cu(II) could play a “mediator” role to form a strong Cu(II)-TCH complex to enhance TCH removal performance. This study provides an effective strategy for the design of magnetic chitosan-based adsorbents and valuable guidance for the removal of tetracyclines from wastewater.

Prediction of Hydrogel Degradation Time Based on Central Composite Design

Prediction of Hydrogel Degradation Time Based on Central Composite Design

Selective Transesterification to Control Copolymer Microstructure in the Ring-Opening Copolymerization of Lactide and ε-Caprolactone by Lanthanum Complexes.

A series of novel lanthanum amido complexes, supported by ligands designed around the salan framework (salan = N,N'-bis(o-hydroxy, m-di-tert-butylbenzyl)-1,2-diaminoethane) were synthesized and fully characterized in the solid and solution states. The ligands incorporate benzyl or 2-pyridyl substituents at each tertiary amine center. The complexes were investigated as catalysts in the ring-opening homopolymerization of lactide (LA) and ε-caprolactone (ε-CL) and copolymerization of equimolar amounts of LA and ε-CL at ambient temperature. Solvent (THF or toluene) and the number of 2-pyridyl groups in the complex were found to influence the reactivity of the catalysts in copolymerization reactions. In all cases, complete conversion of LA to PLA was observed. The use of THF, a coordinating solvent, suppressed ε-CL polymerization, while the presence of one or more 2-pyridyl groups promoted ε-CL polymerization. Each copolymer gave a monomodal trace in gel permeation chromatography-size-exclusion chromatography (GPC-SEC) experiments, indicative of copolymer formation over homopolymerization. Copolymer microstructure was found to be dependent on catalyst structure and reaction solvent, ranging from blocky to close to alternating. Experiments revealed rapid conversion of LA in the initial stages of the reaction, followed by incorporation of ε-CL into the copolymer by either transesterification or propagation reactions. Significantly, the mode of transesterification (TI or TII) that occurs is determined by the structure of the metal complex and the reaction solvent, leading to the possibility of controlling copolymer microstructure through catalyst design.

Preparation and characterization of magnetic microgels with linear thermosensitivity over a wide temperature range

Abstract Hybrid nanogels that are both thermosensitive and superparamagnetic, and have good biocompatibility are expected to have applications in the biomedical field. In this article, a linearly thermosensitive magnetic microgel was prepared by a radical copolymerization reaction in aqueous dispersion. In this reaction, poly(ethylene glycol) diacrylate was used as a crosslinker, polyvinylpyrrolidone was used as a stabilizer, and 2-methoxyethyl acrylate, poly(ethylene glycol)methyl ether acrylate, and 2-(methacryloyloxy)ethyl acetoacetate were used as copolymer monomers. The thermosensitive magnetic microgel displays a linear volume phase transition in water upon heating over a wide range of temperatures. Transmission electron microscopy, scanning electron microscopy, and dynamic light scattering were used to characterize the morphology and dimensions of the thermosensitive magnetic microgel. This material is expected to be used in magnetically targeted drug delivery systems that require linear drug release.

MODIFICATION OF VEGETABLE OILS WITH REACTIVE COMPOUNDS FOR THE PRODUCTION OF PRINTING INKS

The modification of existing paints and varnishes based on alkyd resins, as well as the creation of new film formers using functionalised oligomers to improve the properties of materials in use, has been carried out. The aim of the work is to study vegetable oils used in the production of printing inks and to modify them in order to improve their technological properties. The work carried out allows the use of printing inks based on modified vegetable oils, with the expansion of their scope of application in the production of various printed products. The modification of vegetable oils was carried out by interaction with synthesised urethane-containing reactive block copolymers. Modification of mustard oil allows to change its structure, to increase its molecular weight by oligomerisation of the oil with obtaining of branched structure. Modified vegetable oils provide fast drying alkyd coatings, even in air. The properties of modified oils, the rate of film formation depend on the chemical nature of the block copolymer, its reactivity. The main processes of oil film structuring are due to oxidative and thermal polymerisation of double bonds of fatty acid residues. Optimisation of the vegetable oil modification process has been carried out, a formulation for the production of printing inks has been developed and production tests have been carried out with positive results.

Highly efficient CO2 and propylene oxide co-polymerization using Zn glutarate/Zn-Cr double metal cyanide composite catalyst

A highly active zinc glutarate-double metal cyanide (DMC) composite catalyst (ZnGA/Zn-CrDMC) was designed for the carbon dioxide (CO2) and propylene oxide (PO) copolymerization reaction. The composite catalyst was synthesized in a rheological phase reaction and characterized using Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The synthesized composite catalysed the solvent free reactions of PO and CO2 to afford biodegradable polypropylene carbonate (PPC) copolymer. 1H NMR,13C NMR, FT-IR and ESI-TOF mass spectrometry measurements were employed to confirm the characteristics of the PPC produced. Under optimal reaction conditions (50 bar CO2, 70 °C, 24 h), the ZnGA-Zn3[Cr(CN)6]2 composite displayed higher catalytic activities in the copolymerization reactions than the individual catalysts. The ZnGA:Zn3[Cr(CN)6]2 ratio of 15:1 gave PPC yield of 47.9 g polymer/g cat compared to ZnGA that produced 42.6 g polymer/ g cat in 24 h. In addition, the PPC produced from the composite catalyst displayed higher carbonate linkage content (Fc = 85.4 %) compared to the value of Fc = 33.9 %. obtained using the Zn3[Cr(CN)6]2 catalyst. Similaly, the composite catalsyt produced PPC with molecular weight of 4200 g/mol and narrow polydispersity index of 2.2. The resultant PPC copolymer displayed good thermal stability, exhibiting a high degradation temperatures (TGA-10%) of 229 °C and complete decomposition at 350 °C.

Polydimethylsiloxane Polymerized Emulsions for Acoustic Materials Prepared Using Reactive Triblock Copolymer Surfactants.

Porous polymers have interesting acoustic properties including wave dampening and acoustic impedance matching and may be used in numerous acoustic applications, e.g., waveguiding or acoustic cloaking. These materials can be prepared by the inclusion of gas-filled voids, or pores, within an elastic polymer network; therefore, porous polymers that have controlled porosity values and a wide range of possible mechanical properties are needed, as these are key factors that impact the sound-dampening properties. Here, the synthesis of acoustic materials with varying porosities and mechanical properties that could be controlled independent of the pore morphology using emulsion-templated polymerizations is described. Polydimethylsiloxane-based ABA triblock copolymer surfactants were prepared using reversible addition-fragmentation chain transfer polymerizations to control the emulsion template and act as an additional cross-linker in the polymerization. Acoustic materials prepared with reactive surfactants possessed a storage modulus of ∼300 kPa at a total porosity of 71% compared to materials prepared using analogous nonreactive surfactants that possessed storage modulus values of ∼150 kPa at similar porosities. These materials display very low longitudinal sound speeds of ∼35 m/s at ultrasonic frequencies, making them excellent candidates in the preparation of acoustic devices such as metasurfaces or lenses.

Designing protein-polysaccharides based bioactive copolymeric network by supra-molecular interactions for sustained drug delivery

Keeping in view recent advancements in designing biomaterials from bioactive polysaccharides, the present work deals with the design of protein (gelatin)-polysaccharide (tragacanth gum) based bioactive copolymeric network by supramolecular interactions and covalent linkage for sustained drug delivery (DD) applications. The network copolymeric structure was characterized by field emission-scanning electron micrographs (FE-SEM), electron dispersion X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), 13C-nuclear magnetic resonance (NMR), and X-ray diffraction (XRD). FESEM and XRD analyses revealed the heterogeneous morphology of copolymers with an amorphous nature. 13C NMR and FTIR spectra demonstrated the incorporation of poly(acrylamide) (AAm) into network structure by copolymerization reaction. Diffusion of anticancer drug 5-flurouracil (5-FU) occurred in a sustained manner with the Fickian mechanism and was best fitted in first order kinetic model. Polymer-blood interactions revealed the non-hemolytic character of hydrogels. An antioxidant assay evaluated their antioxidant property (26.61 ± 0.85 % of free radical scavenging). Copolymers exhibited mucoadhesiveness during polymer-mucous membrane interactions and required 113.33 ± 5.68 mN detachment forces. Furthermore, the combination of polysaccharide-gelatin has enhanced supramolecular interactions and improved physiological and biomedical properties of network hydrogels. Overall, these properties revealed the suitability of copolymeric hydrogels for drug delivery applications.

Block copolymer additives for toughening 3D printable epoxy resin

We explore the potential for using a brush-coil triblock copolymer to enhance the mechanical properties of epoxy resin for 3D printing applications. Epoxy resins are widely used in structural material and adhesive and have great potential for 3D printing. However, the highly brittle nature of epoxy resins requires the use of large concentrations of toughening agents that pose significant challenges in meeting rheological requirements of 3D printing. We report a reactive brush-coil block copolymer with three distinct blocks that can phase separate and chemically crosslink with the base epoxy resin to form spherical aggregates. Detailed scanning electron microscopy imaging shows that these aggregates can arrest and deflect cracks during propagation and can synergistically strengthen (∼ 1.5×) and toughen (∼ 2×) the epoxy resin with even 1 wt% of the BCP additive to the base resin. Importantly, both the modulus and the glass transition temperatures are preserved. Direct ink writing (DIW) and digital light processing (DLP) 3D printing of the modified resins also shows the same strengthening and toughening effects seen in mold-cast samples, demonstrating its compatibility with 3D printing processes. These findings suggest that brush-coil triblock copolymers additives at very low concentrations can synergistically improve the mechanical properties of epoxy resin for 3D printed parts.

Polymer Multi-Block and Multi-Block+ Strategies for the Upcycling of Mixed Polyolefins and Other Plastics.

Due to a continued rise in the production and use of plastic products, their end-of-life pollution has become a pressing global issue. One of the biggest challenges in plastics recycling is the separation of different polymers. Multi-block copolymers (MBCPs) represent an efficient strategy for the upcycling of mixed plastics via induced compatibilization, but this approach is limited by difficulties associated with synthesis and structural modification. In this contribution, several synthetic strategies are explored to prepare MBCPs with tunable microstructures, which were then used as compatibilizer additives to upcycle mixtures of polyolefins with other plastics. A multi-block+ strategy based on a reactive telechelic block copolymer platform was introduced, which enabled block extension during the in situ melt blending of mixed plastics, leading to better compatibilizing properties as well as better 3D printing capability. This strategy was also applicable to more complex ternary plastic blends. The polymer multi-block strategy enabled by versatile MBCPs synthesis and the multi-block+ strategy enabled by in situ block extension show exciting opportunities for the upcycling of mixed plastics.

Polymer Multi‐Block and Multi‐Block+ Strategies for the Upcycling of Mixed Polyolefins and Other Plastics

AbstractDue to a continued rise in the production and use of plastic products, their end‐of‐life pollution has become a pressing global issue. One of the biggest challenges in plastics recycling is the separation of different polymers. Multi‐block copolymers (MBCPs) represent an efficient strategy for the upcycling of mixed plastics via induced compatibilization, but this approach is limited by difficulties associated with synthesis and structural modification. In this contribution, several synthetic strategies are explored to prepare MBCPs with tunable microstructures, which were then used as compatibilizer additives to upcycle mixtures of polyolefins with other plastics. A multi‐block+ strategy based on a reactive telechelic block copolymer platform was introduced, which enabled block extension during the in situ melt blending of mixed plastics, leading to better compatibilizing properties as well as better 3D printing capability. This strategy was also applicable to more complex ternary plastic blends. The polymer multi‐block strategy enabled by versatile MBCPs synthesis and the multi‐block+ strategy enabled by in situ block extension show exciting opportunities for the upcycling of mixed plastics.

Polyetherimide nanocomposites filled with in‐situ synthesised bismaleimide‐DDE@CCTO hybrid nanofibers enabling improved dielectric and interfacial performance

AbstractMost current research of nanocomposite dielectrics for modern electronic devices and electric equipment usually focuses more on dielectric properties while in some extent ignoring the interfacial adhesion characteristics. However, the poor interfacial adhesion frequently results in serious dielectric field distortion, which would in return impair the dielectric performance enhancement. As such, how to simultaneously achieve the excellent dielectric properties and interfacial adhesion performance in organic‐inorganic nanocomposite system is worth in‐depth investigation. To realise this aim, novel hybrid nanofibers are neatly fabricated using in situ copolymerisation reaction of bismaleimide and diamino‐diphenyl ether monomers on the CCTO nanofiller surface via covalent bond connections. The resulting nanocomposites achieve high dielectric constant (9.3) and low dielectric loss (0.0185) at 1 kHz. The BMI‐DDE@CCTO/PEI yields a high discharge energy density (3.09 J/cm3) at moderate electric field (200 MV/m). Noticeably, the nanocomposites enable stable dielectric performance over a wide temperature range from room temperature to 150°C. Moreover, the binding energy for BMI‐DDE and PEI is 1052 kJ/mol according to DFT calculation. As such, the authors speculate this interesting study would inspire the broad researchers devoting to investigating bismaleimide‐coated high‐aspect‐ratio nanofillers and their dielectric materials for collaboratively improved dielectric and interfacial performance.

Electrical and Electromagnetic Characteristics of Poly (Methyl Methacrylate)/Polyaniline PMMA/PANi Conductive Film

In this study, a conductive film of poly (methyl methacrylate)/polyaniline (PMMA/PANi) was fabricated through a free radical copolymerization reaction using methyl methacrylate (MMA) and aniline monomers at different aniline-to-MMA ratios, namely, 1:1, 1:3, and 1:5. The PMMA/PANi copolymer films exhibited a total electromagnetic interference (EMI) shielding effectiveness (SET) of 0.45, 0.60, and 1.22 dB, respectively, which is more than twice that of the pure PMMA film (0.16 dB). The copolymer films possess the highest conductivity of 2.34 x 10−6 S/cm at the optimum value of aniline for films polymerized with a 1:3 PMMA:PANi ratio. Higher conductivity materials exhibited lower resistance and, thus, absorbed more EM energy, resulting in better EMI shielding

Mechanistic Studies on Aluminum-Catalyzed Ring-Opening Alternating Copolymerization of Maleic Anhydride with Epoxides: Ligand Effects and Quantitative Structure-Activity Relationship Model.

Previous work has indicated that aluminum (Al) complexes supported by a bipyridine bisphenolate (BpyBph) ligand exhibit higher activity in the ring-opening copolymerization (ROCOP) of maleic anhydride (MAH) and propylene oxide (PO) than their salen counterparts. Such a ligand effect in Al-catalyzed MAH-PO copolymerization reactions has yet to be clarified. Herein, the origin and applicability of the ligand effect have been explored by density functional theory, based on the mechanistic analysis for chain initiation and propagation. We found that the lower LUMO energy of the (BpyBph)AlCl complex accounts for its higher activity than the (salen)AlCl counterpart in MAH/epoxide copolymerizations. Inspired by the ligand effect, a structure-energy model was further established for catalytic activity (TOF value) predictions. It is found that the LUMO energies of aluminum chloride complexes and their average NBO charges of coordinating oxygen atoms correlate with the catalytic activity (TOF value) of Al complexes (R2 value of 0.98 and '3-fold' cross-validation Q2 value of 0.88). This verified that such a ligand effect is generally applicable in anhydride/epoxide ROCOP catalyzed by aluminum complex and provides hints for future catalyst design.

Lube Oil Performance Enhancement Using Nano-Polymers Additives during Copolymerization Reaction

Under the parameters of normal engine operation, lubricating oil typically experience periodic shifts in its viscosity. Because of this, engine oils often include polymeric additives that are referred to as viscosity modifiers. The oil is able to give acceptable fluid lubrication at extreme temps due to these additives, which are oil-soluble polymers. The aim of present work to use polymers in form of nano-composites such as Styrene, Octadecyl-methacrylate (ODMC) and Dodecyle-methcrylate (DDMC) for lube oil viscosity index and pour point enhancement during copolymerization reaction. The benzoyl peroxide was used as an initiator. Solubilizes were made using SN-150 mineral base oil from the Al-Dorha refineries in Baghdad, which had a viscosity index of 128, and a viscosity range of 0 to 100°C. Styrene and methacrylate monomer combinations were copolymerized in an SN-150 mineral base oil solution in a nitrogen atmosphere at 60-80°C. A 200 mm3 oil glass reactor fitted with a magnetic stirrer and a reflux condenser was used to conduct the reactions. Five percent by weight of the total monomer was the concentration used. With respect to the monomers, the initiator concentration was 1.0% wt. Seven hours are needed for the whole reaction cycle. The copolymer composition was modified from 5 to 25% wt.% styrene by changing the monomer combination ratio. The advanced statistical analysis is performed to find the optimum conditions by mean of surface response and multiple regression using MINITAB. The optimization finding is obtained at Styrene of 5%, DDMC of 18% and ODMC of 18%, which promotes viscosity index of 197 leading to 51% enhancement in Al-Dora lube oil.

4D-Printable Photocrosslinkable Polyurethane-Based Inks for Tissue Scaffold and Actuator Applications.

4D printing recently emerges as an exciting evolution of conventional 3D printing, where a printed construct can quickly transform in response to a specific stimulus to switch between a temporary variable state and an original state. In this work, a photocrosslinkable polyethylene-glycol polyurethane ink is synthesized for light-assisted 4D printing of smart materials. The molecular weight distribution of the ink monomers is tunable by adjusting the copolymerization reaction time. Digital light processing (DLP) technique is used to program a differential swelling response in the printed constructs after humidity variation. Bioactive microparticles are embedded into the ink and the improvement of biocompatibility of the printed constructs is demonstrated for tissue engineering applications. Cell studies reveal above 90% viability in 1 week and ≈50% biodegradability after 4 weeks. Self-folding capillary scaffolds, dynamic grippers, and film actuators are made and activated in a humid environment. The approach offers a versatile platform for the fabrication of complex constructs. The ink can be used in tissue engineering and actuator applications, making the ink a promising avenue for future research.

Functionalization of bioactive moringa gum for designing hydrogel wound dressings

In view of wound healing properties of moringa gum (MG) and the antibacterial activity of poly(METAC), in the present work, the antibiotic drug ofloxacin encapsulated MG-cl-poly(METAC) based hydrogel dressings were prepared by graft copolymerization reaction for better wound care. Network copolymeric structure was assessed by FESEM, AFM, EDX, 13C NMR, XRD, FTIR and DSC techniques. Swelling properties demonstrated that the network density of hydrogel dressings could be tailored as per the need of wound fluid sorption by controlling feed monomer and crosslinker content during synthesis. FESEM, AFM and XRD revealed a heterogeneous morphology of hydrogels with a rough surface and an amorphous patterns of polymeric materials. Diffusion of ofloxacin from dressing occurred by a non-Fickian diffusion mechanism in simulated wound fluid and was fitted best in First-order kinetic model. Wound dressings exhibited non-haemolytic (0.97% haemolytic potential), mucoadhesive (109.00 ± 4.00 mN peak detachment force) and antioxidant (92.94 ± 2.13% scavenging in DPPH assay) characteristics along with mechanical strength against external stress and strain. Hydrogel dressings were found to be permeable to H2O/O2 and impermeable to microbes. The synergic action of the drug and matrix with antibacterial activity can improve the wound-healing potential of the dressings. These physiological and biomedical properties pointed out the ideal character of moringa gum dressings for better wound healing.

Synthesis and antitumor activity of bagasse xylan derivatives modified by graft-esterification and cross-linking

A crucial aspect in achieving sustainable development of biomass materials is the modification of renewable polysaccharides to create various high-value functional materials. In this paper, bagasse xylan (BX) was used as a raw material to introduce benzyl methacrylate (BMA) through graft copolymerization reaction to generate the intermediate product BX-g-BMA. Subsequently, the target product (CA-BX-g-BMA) was synthesized by catalytic esterification of BX-g-BMA with citric acid (CA) in AmimCl ionic liquid. Meanwhile, the characterization and bioactivity studies of CA-BX-g-BMA were carried out. The graft copolymerization and esterification reactions induced significant changes in the morphological structure of BX and obviously improved its thermal stability and crystallinity. The application of density functional theory (DFT), molecular electrostatic potential (MEP) and molecular docking has revealed that CA-BX-g-BMA possesses multiple active sites, strong biological activity and a strong binding affinity to 6RCF tumor protein with a binding energy of −32.26 kJ/mol. The in vitro antitumor activity of this novel derivative was tested by MTT assay, and the results showed that CA-BX-g-BMA was non-toxic to normal cells and inhibited MDA-MB-231 (breast cancer cells) by up to 32.16 % ± 4.89 %, which is approximately 11 times higher than that of BX. The exploration of these properties is essential to promote future multidisciplinary applications of BX derivatives.

Multinuclear Zinc-Magnesium Hydroxide Carboxylates: A Predesigned Model System for Copolymerization of CO2 with Epoxides.

Among numerous catalysts in the ring-opening copolymerization of epoxides with carbon dioxide (CO2), zinc dicarboxylate complexes are the most common type, and in the family of metal-based homogeneous catalysts, zinc and magnesium complexes have attracted widespread attention. We report on the synthesis and structural characterization of a zinc-magnesium benzoate framework templated by the central hydroxide anion with μ3-κ2:κ2:κ2 coordination mode, [ZnMg2(μ3-OH)(O2CPh)5]n (n = 1 or 2). The resulting heterometallic system forms stable Lewis acid-base adducts with tetrahydrofuran (THF) and cyclohexene oxide (CHO), which crystallize as the hexanuclear zinc-magnesium hydroxide carboxylate cluster [ZnMg2(μ3-OH)(O2CPh)5(L)2]2 (L = THF or CHO). Their X-ray crystal structure analysis revealed that the Zn center prefers 4-fold coordination and the Mg centers demonstrated the ability to accommodate higher coordination numbers, and as a result, the heterocyclic molecules are exclusively bonded to 6-fold Mg atoms. The heteronuclear carboxylate aggregates appeared active in the copolymerization reaction at elevated temperatures to produce an alternating poly(cyclohexene carbonate).