Search Results (132)

In this study, COOH-functionalized co-polymer of acrylonitrile and itaconic acid (P(AN-co-IA)) is synthesized via free radical copolymerization using DMSO as solvent. The continuous non-aligned carbon nanofibers (CNFs) with different amounts of metallocene (zirconocene and ferrocene) are fabricated through electrospinning, followed by a series of heat treatments under an inert atmosphere. The influence of metallocenes on electrospun carbon nanofiber diameter, alignment, and structural ordering was systematically investigated using FESEM, XRD, Raman spectroscopy, and TEM. Incorporation of dual metallocenes significantly alters the fiber diameter, improves orientation, and promotes graphitic domain formation at 1100 °C, a much lower temperature than conventional graphitization. The optimized sample (Zr-Fe)₁-P(AN-co-IA)-eGNF) exhibited the lowest I_D/I_G ratio compared to pristine and all prepared samples, indicating an improved degree of graphitization due to the uniform distribution of metallocene nanofiber matrix. Furthermore, the electrical conductivity of optimized (Zr-Fe)₁-P(AN-co-IA)-eGNF reached the highest value (1654.5 S/m) due to the high degree of graphitization of carbon nanofibers. These results show that integrating dual metallocene is an efficient pathway for tailoring nanofiber morphology and achieving conductive, structurally ordered electrospun eGNFs at reduced temperatures, with potential applications in various fields. Full article

A polyacrylamide-based film-forming agent was synthesized via free-radical copolymerization. FT-IR spectroscopy confirmed complete monomer conversion with no detectable residual unsaturation. Systematic variation of acrylamide (AM), vinyl acetate (VAc) and cellulose content revealed that an AM mass fraction of 3.7 wt%, a VAc:AM molar ratio of 1:3 and a cellulose content of 1.6 wt% yielded an emulsion of maximal colloidal stability. Under these conditions, the agent formed coherent, moisture-resistant films that effectively encapsulated sodium-bentonite pellets, indicating its potential as an efficient inhibitor for maintaining well-bore stability during drilling operations. Full article

This study reports the first synthesis of a new type of ether-polyalphaolefin (DVE-PAO) base oil via free radical bulk copolymerization using triethylene glycol divinyl ether (DVE-3) and α-olefin in drip-feed mode. The characteristic structure of DVE-PAO was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Nuclear Magnetic Resonance Spectroscopy (NMR). The relative molecular weight and molecular weight distribution of DVE-PAO were determined using gel permeation chromatography (GPC). Structurally, it is a new type of base oil that integrates both polyalkylene glycol (PAG) and polyalphaolefin (PAO) structural units. The research shows that the viscosity of DVE-PAO base oil, the conversion rate of α-olefin, and the pour point of the copolymer increase with rising copolymerization temperature. Additionally, results from the rotating oxygen bomb test indicate that the oxidation stability of DVE-PAO also improves with increasing viscosity. Based on the principles of free radical copolymerization, this study provides a preliminary elucidation of the copolymerization patterns between the aforementioned double-ended vinyl ethers and α-olefins. Furthermore, the DVE-PAO base oil exhibits excellent miscibility with both mineral oils and polyalphaolefin (PAO) base oils. As a result, this ether-based polyalphaolefin is expected to find broad applications in the field of lubricants. Full article

In this study, we present a novel and straightforward approach for the synthesis of copolymers and nanocomposites based on α- and β-pinene, employing an eco-friendly and cost-effective nano-reinforcing filler. The copolymers (α-co-β-P) were produced through cationic copolymerization, using AlCl₃ as a catalyst. The structural characterization of the resulting copolymer was validated through FT-IR, ¹H-NMR spectroscopy, and differential scanning calorimetry (DSC). The molecular weight of the obtained polymer is determined by Gel Permeation Chromatography (GPC) analysis and is about 4500 g/mol. Nanocomposites (α-co-β-P/Clay 2, 5, 8, and 10% by weight of nano-clay) were synthesized by combining clay and α-co-β-P copolymer in solution using ultrasonic irradiation. This ultrasound-assisted method was employed to enhance and assess the structural, morphological, and thermal properties of the pure copolymer. The morphology of the resultant nanocomposites was characterized using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thermogravimetric analysis (TGA) revealed that the nanocomposites exhibit a higher degradation temperature compared to the pure copolymer. The analyses provided evidence of the chemical modification of nano-clay layers and their uniform dispersion in the α-co-β-P copolymer matrix. Exfoliated structures were achieved for lower clay concentration (2% by weight), while intercalated structures and immiscible regions were observed for higher clay concentrations (5, 8, and 10% by weight). The antioxidant activity of α-pinene, β-pinene, and the obtained nanocomposites were studied using DPPH (2,2-diphenyl-1-picrylhydrazyl) as a model free-radical. The results demonstrate a significant antioxidant potential of the nanocomposites, showcasing their ability to effectively neutralize free-radicals. Finally, a novel procedure was devised for the rapid synthesis of copolymers and nanocomposites using α- and β-pinene. Full article

Cyclic Olefin Copolymer (COC) is an amorphous thermoplastic polymer synthesized through the catalytic copolymerization of α-olefin and cyclic olefin. When used in pre-filled syringes and pharmaceutical packaging, COCs require radiation sterilization. The radiation sterilization alters the microstructure of COC, which ultimately affects its performance and biosafety. In this study, to investigate the effects of γ-radiation on COC microstructures, ethylene-norbornene copolymers with various compositions, representative of COC, are studied by nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. During irradiation, the COC containing 35 mol% norbornene produced free radicals that triggered migration and reaction processes, leading to the formation of entanglements within flexible chain segments. This, in turn, affected nearby ring structures with high steric hindrance, resulting in a 9.2% decrease in internal particle size and an increase in particle spacing. Conversely, when the norbornene content in COC was increased to 57 mol%, the internal particle size increased by 17.9%, while the particle spacing decreased. Full article

Polymer conetworks, which consist of two or more covalently crosslinked polymer chains, not only combine the individual characteristics of their components, but possess various unique structural features and properties as well. In this study, we report on the successful synthesis of a library of polystyrene-l-poly(dimethylsiloxane) (PSt-l-PDMS) (“l” stands for “linked by”) and polystyrene-l-poly(dimethylsiloxane)/divinylbenzene (PSt-l-PDMS/DVB) polymer conetworks. These conetworks were prepared via free radical copolymerization of styrene (St) with methacryloxypropyl-telechelic poly(dimethylsiloxane) (MA-PDMS-MA) as macromolecular crosslinker in the absence and presence of DVB with 36:1 and 5:1 St/DVB ratios (m/m), the latter leading to hypercrosslinked conetworks. Macroscopically homogeneous, transparent conetworks with high gel fractions were obtained over a wide range of PDMS contents from 30 to 80 m/m%. The composition of the conetworks determined by elemental analysis was found to be in good agreement with that obtained from the ¹H NMR spectra of the extraction residues, as a new method which can be widely used to easily determine the composition of multicomponent networks and gels. DSC, SAXS, and AFM measurements clearly indicate bicontinuous disordered nanophase separated morphology for all the investigated conetworks with domain sizes in the range of 3–30 nm, even for the hypercrosslinked PSt-l-PDMS/DVB conetworks with extremely high crosslinking density. The cocontinuous morphology is also proved by selective, composition-dependent uniform swelling in hexane for the PDMS and in 1-nitropropane for the PSt domains. The Korsmeyer–Peppas type evaluation of the swelling data indicates hindered Fickian diffusion of both solvents in the conetwork organogels. The unique nanophasic bicontinuous morphology and the selective swelling behavior of the PSt-l-PDMS and PSt-l-PDMS/DVB conetworks and their gels offer a range of various potential applications. Full article

Poly (styrene-maleic anhydride) copolymers, due to their unique structure, are extensively functionalized and modified for preparing heat stabilizers, compatibilizers, and other functional additives. Using 4-methylpent-1-ene-2,4-diyl diphenyl (α-MSD) as a chain transfer agent, a series of molecular-weight-controlled maleic anhydride-derived styrene copolymers, poly(N-p-fluorophenylmaleimide-alt-styrene) (PFS) and poly(N-p-carboxylphenylmaleimide-alt-styrene) (PCS), were synthesized via free radical copolymerization. The molecular weights of PFS and PCS were adjusted to explore their impact on the properties of PFS/PA6 and PCS/PA6 blends. Gel permeation chromatography (GPC) analysis confirmed that α-MSD effectively regulated the molecular weights of PFS and PCS. PFS and PCS with lower molecular weights exhibited significantly reduced viscosity, with minimal impact on their thermal and mechanical properties. Full article

N-isopropylacrylamide and methacrylic acid were copolymerized by a free radical polymerized mechanism. The obtained hydrogel poly(N-isopropylacrylamide-co-methacrylic acid) hydrogels, poly(NIPAM-co-MAA), were utilized as sorbent material for removal Cr(VI), Mn(II), and Pb(II) ions from simulated aqueous solutions. Hydrogel structures before and after heavy metal sorption are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The swelling results indicate that poly(NIPAM-co-MAA) hydrogels are pH- and temperature-sensitive and have high swelling reversibility through three swelling/contraction cycles. The studied parameters of heavy metal sorption include the effect of pH, the initial concentration of heavy metal, the effect of temperature, and the desorption of metal ions. The maximum sorption capacities of poly(NIPAM-co-MAA) hydrogels were determined at pH 4.5 and 25 °C, and they are, for Cr(VI), Mn(II), and Pb(II) ions, 289.35 mg/g, 190.59 mg/g, and 349.71 mg/g, respectively. The pseudo-second-order model and the Langmuir adsorption isotherm best describe the sorption of heavy metal ions onto hydrogels. The removal of heavy metals is an exothermic reaction, and the interaction mechanism between the metal and the hydrogel is primarily physical in nature. Results of three sorption/desorption cycles show a good desorption ratio and sorption capacity of poly(NIPAM-co-MAA) hydrogels. Full article

Poly(N-isopropylacrylamide) (PNIPAm) undergoes a sharp phase transition in aqueous solutions at around 32 °C, which is called the lower critical solution temperature; the tuning of the LCST of PNIPAm could be achieved by the copolymerization of N-isopropylacrylamide (NIPAm) with other hydrophilic/hydrophobic monomers to regulate the solvation state of PNIPAm and meet the requirements of possible applications. Herein, a hydrophilic monomer, 2,3-dihydroxypropyl methacrylate (DHPMA), w introduced to regulate the phase transition behavior of PNIPAm via free radical copolymerization. A series of poly(N-isopropylacrylamide-co-2,3-dihydroxypropyl methacrylate) (P(NIPAm-co-DHPMA)) was synthesized and characterized. The reaction kinetics were investigated in detail. In this copolymerization, the reactivity ratios of DHPMA and NIPAm were found to be 3.09 and 0.11, suggesting that DHPMA had greater preference for homopolymerization than for copolymerization, while NIPAm had greater preference for copolymerization than for homopolymerization. The phase transition temperature of P(NIPAm-co-DHPMA) copolymers varied from 31 to 42 °C by controlling the content of DHPMA in the copolymers from 0 to 58 mol%. Finally, the good cytocompatibility of P(NIPAm-co-DHPMA) was confirmed. These results provide insights into designing thermo-responsive polymers with suitable responsive behaviors that meet the requirements of different applications. Full article

Porous polymer membranes with highly interconnected open-cellular structure and high toughness are crucial for various application fields. Polymerized high internal phase emulsions (polyHIPEs), which usually exist as monoliths, possess the advantages of high porosity and good connectivity. However, it is difficult to prepare membranes due to brittleness and easy pulverization. Copolymerizing acrylate soft monomers can effectively improve the toughness of polyHIPEs, but it is easy to cause emulsion instability and pore collapse. In this paper, stable HIPEs with a high content of butyl acrylate (41.7 mol% to 75 mol% based on monomers) can be obtained by using a composite emulsifier (30 wt.% based on monomers) consisting of Span80/DDBSS (9/2 in molar ratio) and adding 0.12 mol·L⁻¹ CaCl₂ according to aqueous phase concentration. On this basis, polyHIPE membranes with high open-cellular extent and high toughness are firstly prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization. The addition of the RAFT agent significantly improves the mechanical properties of polyHIPE membranes without affecting open-cellular structure. The toughness of polyHIPE membranes prepared by RAFT polymerization is significantly enhanced compared with conventional free radical polymerization. When the molar ratio of butyl acrylate/styrene/divinylbenzene is 7/4/1, the polyHIPE membrane prepared by RAFT polymerization presents plastic deformation during the tensile test. The toughness modulus reaches 93.04 ± 12.28 kJ·m⁻³ while the open-cellular extent reaches 92.35%, and it also has excellent thermal stability. Full article

During the manufacture of high-strength concrete, its sensitivity to variations inconcrete mixing water, the poor adaptability of cement, and high hydration temperatures are often encountered. Therefore, in this paper, firstly, the esterification reaction of methoxy polyethylene glycol ether (MPEG) and methacrylic acid (MAA) was carried out. According to the different molecular weights of MPEG, three kinds of esterification products (MPEG-MAA) were synthesized. Three kinds of PCE-st were synthesized by free-radical copolymerization of three kinds of MPEG-MAA, ethylene glycol polyethylene glycol ether (EPEG), and acrylic acid (AA), and their effects on the properties of cement paste and concrete were analyzed. The results revealed that when the water–cement ratio increased from 0.25 to 0.31, PCE-st with MPEG with a molecular weight of 600 optimally reduced the water content variation sensitivity and increased the fluidity of cement pastes by only 62 mm, while PCE-st with smaller and larger molecular weights of MPEG increased the fluidity by 94 mm and 80 mm, respectively. As the molecular weight of MPEG increased from 400 to 1200, the hydration temperature decreased from 43.8 °C to 39.5 °C, and the setting time was delayed by about 30 min. Finally, the compressive strength of concrete made with PCE-st was similar to that of the concrete made with commercially available PCE-et0. Full article

Conventional waterborne polyurethane (WPU) has poor water resistance and poor overall performance, which limits its application in outdoor coatings. A solution to this problem is urgently needed. The introduction of fluorine-containing groups can effectively improve the water resistance of WPU. In this study, a new fluorinated chain extender (HFBMA-HPA) synthesized by free radical copolymerization and epoxy resin (E-44) were used to co-modify WPU, and five waterborne fluorinated polyurethane (WFPU) emulsions with different fluorine contents were prepared by the self-emulsification method. The effects of HFBMA-HPA content on the emulsion particle properties, coating surface properties, mechanical properties, water resistance, thermal stability, and corrosion resistance were investigated. The results showed that the WFPU coating had excellent thermal stability, corrosion resistance, and mechanical properties. As the content of HFBMA-HPA increased from 0 wt% to 14 wt%, the water resistance of the WFPU coating gradually increased, the water contact angle (WCA) increased from 73° to 98°, the water absorption decreased from 7.847% to 3.062%, and the surface energy decreased from 32.8 mN/m to 22.6 mN/m. The coatings also showed impressive performances in the adhesion and flexibility tests in extreme conditions. This study provides a waterborne fluorinated polyurethane material with excellent comprehensive performance that has potential application value in the field of outdoor waterproof and anticorrosion coatings. Full article

A random copolymer (PTBM), utilized as deep ultra-violet (DUV) photoresist, was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization with tert-butyl methacrylate (tBMA), methyl methacrylate (MMA), triphenylsulfonium p-styrenesulfonate (TPS-SS), and functional poly (sesquicarbonylsiloxanes) (POSS-MA) as the monomer components, and 4-cyano-4-[(dodecylsulfanylthiocarbonyl) sulfanyl]pentanoic acid (CDSPA) as the RAFT reagent. Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (¹H NMR) proved successful synthesis. Ultraviolet absorption spectroscopy (UV) analysis verified the transparency of the polymer in the DUV band. RAFT polymerization kinetics showed that the polymerization rate conformed to the first-order kinetic relationship, and the polymerization process exhibited a typical controlled free radical polymerization behavior. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and static thermo-mechanical analysis (TMA) showed that the incorporation of POSS groups improved the thermal properties of the copolymer. According to scanning electron microscopy (SEM) images, the copolymerization of photoacid monomers (TPS-SS) resulted in photoresist copolymers exhibiting good resistance to acid diffusion and low roughness. Full article

An alternative synthetic pathway was proposed for the optimization of synthesis to find a better correlation between the swelling and elasticity of hyaluronic acid-interpenetrated gels via temperature regulation. An experimental design methodology was presented for the synthesis of polyacrylamide/poly(acrylic acid sodium salt)/hyaluronic acid, PAAm/PSA/HyA, gels by modifying the one-pot procedure using free radical crosslinking copolymerization of AAm with the addition of anionic linear PSA chains in the presence of various amount of HyA, ranging between 0.05% and 0.20% (w/v). Semi-interpenetrated polymer network (IPN)-structured gels were designed with tunable elasticity, in which the extent of covalent crosslinking interactions is controlled by polymerization temperature ranging between −18 and 45 °C. Depending on the HyA content added in the synthesis and the polymerization temperature, the swelling ratio could be controlled. The addition of 0.05% (w/v) HyA increased the swelling of semi-IPNs, while the elastic modulus increased with increasing HyA content and decreased with the polymerization temperature. PAAm/PSA/HyA semi-IPNs showed the typical pH-sensitive swelling of anionic gels, and the swelling reached a maximum at a pH of 11.2. PAAm/PSA/HyA gels were tested for the removal of methyl violet from wastewater. Adsorption kinetics were shown to be well-fitted with the pseudo-second-order model using linear and nonlinear regression analysis. With the clear relationship between increased modulus and composition, this study enabled the fine-tuning of semi-IPN interactions by varying the polymerization temperature. Full article

In this paper, N-vinylpyrrolidone was copolymerized with acrylic acid and itaconic acid by free radical polymerization, and a series of polyacrylic acid-co-itaconic acid-co-N-vinylpyrrolidone (PAIN) dispersants with different pyrrolidone ligand contents were synthesized and characterized. Then, the cobalt blue nano-pigment slurry (20 wt%) was prepared through a water-based grinding method, and the optimum grinding technology was explored and determined as follows: PAIN2 as a dispersant, a dispersant dosage of 10 wt%, and a grinding time of 480 min. According to this optimum grinding technology, the prepared pigment slurry had a significantly decreased agglomeration, the D₉₀ of which was 82 nm, and separately increased to 130 nm and 150 nm after heat storage for 3 and 7 days, exhibiting excellent heat storage stability. Additionally, its TSI value was also the lowest (1.9%), indicating good dispersion stability. The QCM and adorption capacity measuring results showed PAIN2 had a larger adsorption capacity, and the formed adsorption layer had a higher rigidity and was not easy to fall off. This was caused by both the interaction of carboxyl groups and the pyrrolidone ligand (strong coordination interaction) in PAIN2 with cobalt blue. The XPS and FT–IR measurements further proved the above-mentioned adsorption mechanism. Full article