Free Radical Polymerization Process Research Articles

Low-cost, all-organic, hydrogen-bonded thin-film composite membranes for CO2 capture: Experiments and molecular dynamic simulations

Despite the excellent separation performance of organic-inorganic hybrid membranes, such as mixed-matrix membranes, their commercial application remains challenging due to difficulties in uniformly dispersing inorganic fillers and achieving good interfacial contact over large areas. In this paper, we present high-performance, thin-film composite (TFC) membranes made from low-cost, all-organic materials using a commercially attractive and straightforward process for CO2 capture. The TFC membranes were prepared on a porous polysulfone support using 2,4,6-triaminopyrimidine (TAP) dispersed in comb-shaped polymerized poly(oxyethylene methacrylate) (PPOEM), synthesized through a free radical polymerization process. The organic filler TAP functioned as a hydrogen bond inducer, controlling the free volume and reducing gas diffusivity, thereby enhancing CO2 selectivity over larger gases such as N2 and CH4. Incorporating 2 wt% TAP significantly improved separation performance by primarily reducing N2 and CH4 permeances, achieving a CO2 permeance of 1140 GPU, with CO2/N2 and CO2/CH4 selectivities of 43.3 and 15.0, respectively. The achieved performance significantly surpassed that of Pebax-based membranes and successfully met the target criteria for post-combustion CO2 capture. Variations in free volume, molecule aggregation, hydrogen bonding, and interaction energies between gases and membranes were thoroughly investigated via molecular dynamic (MD) simulations. This high-performance TFC membrane, created through simple and facile methods using entirely organic materials, achieves commercial standards for post-combustion CO2 capture.

Gelatin-based carbon quantum dot-molecularly imprinted polymer: Safe photoluminescent core-shell nano-carrier for the pH-responsive anticancer drug delivery

This study aims to synthesize a core-shell gelatin-based carbon quantum dot-molecularly imprinted polymer (MIP@g-CQD) via the precipitation free-radical polymerization process using methotrexate (MTX) as a model anticancer template. To investigate the efficiency of the prepared photoluminescent MIP@g-CQD as a pH-responsive nano-carrier, MTX was loaded into MIP@g-CQD by soaking in a drug solution and the release behavior of the loaded drug was evaluated in the necessary pH values (7.4, 5). The successful synthesis of materials was characterized using PL, TEM, FE-SEM, DLS, and FT-IR analyses. Interestingly, the created cavities in the core-shell nano-carriers can interact with the MTX molecules effectively, leading to an increase in the loading capacity. According to the obtained results from Langmuir adsorption isotherms, the imprinting factor was calculated (IF = 4.91). Also, the binding kinetics of MTX revealed the creation of particular recognition sites in the core-shell polymeric network. The MTX-loaded MIP@g-CQD displayed a low rate and limited release at the simulated physiological environment (pH 7.4, 37 °C), but it is increased at tumor tissue (pH 5, 41 °C) conditions, which can lead to long-term and sustained release of MTX in the desired target. This property of MIP@g-CQD could avoid the release of MTX in normal physiological conditions, decreasing the possible side effects of MTX drug. Owing to the existence of amide functional groups in the nano-carrier structure and its negatively charged nature, the MTT assay displayed desirable cytotoxicity against the breast cancer cell line (MCF-7) for the MTX-loaded nano-carrier. According to the obtained results, the prepared safe photoluminescent MIP@g-CQD with appropriate pH-responsivity has a high ability to be applied as an anticancer and bio-detection agent.

Fabrication, optimization, and in vitro validation of penicillin-loaded hydrogels for controlled drug delivery

Bacterial infections present a major global challenge. Penicillin, a widely used antibiotic known for its effectiveness and safety, is frequently prescribed. However, its short half-life necessitates multiple high-dose daily administrations, leading to severe side-effects. Therefore, this study aims to address these issues by developing hydrogels which control the release of penicillin and alleviate its adverse effects. Various combinations of aspartic acid and acrylamide were crosslinked by N′, N′-methylene bisacrylamide through a free radical polymerization process to prepare aspartic acid/acrylamide (Asp/Am) hydrogels. The fabricated hydrogels underwent comprehensive characterization to assess physical properties and thermal stability. The soluble and insoluble fractions and porosity of the synthesized matrix were evaluated by sol-gel and porosity studies. Gel fraction was estimated at 88–96%, whereas sol fraction was found 12–4% and porosity found within the 63–78% range for fabricated hydrogel formulations. Maximum swelling and drug release were seen at pH 7.4, demonstrating a controlled drug release from hydrogel networks. The results showed that swelling, porosity, gel fraction, and drug release increased with higher concentrations of aspartic acid and acrylamide. However, integration of N′, N′-methylene bisacrylamide exhibited the opposite effect on swelling and porosity, while increasing gel fraction. All formulations followed the Korsymer–Peppas model of kinetics with ‘r’ values within the range of 0.9740–0.9980. Furthermore, the cytotoxicity study indicated an effective and safe use of hydrogel because the cell viability was higher than 70%. Therefore, these prepared hydrogels show promise candidates for controlled release of Penicillin and are anticipated to be valuable in clinical applications.

Fluorescent zinc acrylate resins containing coumarin structures with enhanced antifouling performance

The demand for non-toxic antifouling coatings has led to the development of multifunctional antifouling coatings. In this work, a series of coumarin acids with fluorescence were first prepared via the Knoevenagel condensation reaction. Then, multifunctional zinc acrylate resins were produced successfully by employing an acrylic acid monomer, ZnO, and coumarin acids by free radical polymerization and polycondensation processes. The self-polishing and antifouling properties of the resins were investigated by dynamic simulation experiments, E. coli growth inhibition experiments, algae adhesion inhibition experiments, and marine environment antifouling experiments. The results show that the zinc acrylate resins containing the coumarin structures not only have good self-polishing performance but also have better antifouling performances than the zinc acrylate resin containing benzoic acid. This work not only reveals the antifouling mechanism of the multifunctional resins, but also provides a new strategy for the development of environmentally friendly antifouling coatings.

Using the Quartz Crystal Microbalance to Monitor the Curing of Drying Oils.

Drying oils such as linseed oil form a polymer network through a complex free-radical polymerization process. We have studied polymerization in this challenging class of polymers using a quartz crystal microbalance (QCM). The QCM is able to measure the evolution of polymer mass and mechanical properties as the oil transitions from a liquid-like to a solid-like state. Measurements using bulk materials and thin films provide information about the initial polymerization phase as well as the evolution of the mass and mechanical properties over the first two years of cure. The temperature-dependent response of the cured linseed oil films was also measured. These results were combined with previously published results obtained from traditional dynamic mechanical analysis to give a unified picture of the properties of these materials across a very broad temperature range.

PH-responsive biomass-based hydrogels for 5-fu delivery: Investigating the influential role of itaconic acid content on structural characteristic, swelling behavior, and drug loading capacity

The pH-responsive hydrogel was synthesized through an eco-friendly free radical polymerization process, utilizing ionic acid (IA), N, N-dimethyl acrylamide (DAAm), and double-bond modified vanillin (VMA). The P(DAAm-co-IA-co-VMA) hydrogel exhibited favorable compressive strength, swelling behavior, temperature sensitivity, pH sensitivity, salt solution sensitivity, and biocompatibility. Additionally, the study investigated the influence of varying IA monomer content on these properties. The evaluation of drug loading and release capabilities utilized 5-fluorouracil (5 Fu) as the model medicinal. The results showed that the P(DAAm-co-IA-co-VMA) hydrogel's cumulative release percentage was greater in the simulated intestinal fluid compared to the simulated gastric fluid, indicating its potential for oral drug delivery applications.

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.

Ultrafast Sunlight-Induced Polymerization: Unveiling 2-Phenylnaphtho[2,3-d]Thiazole-4,9-dione as a Unique Scaffold for High-Speed and Precision 3D Printing.

A series of 15 dyes based on the 2-phenylnaphtho[2,3-d]thiazole-4,9-dione scaffold and 1 compound based on the 2,3-diphenyl-1,2,3,4-tetrahydrobenzo[g]quinoxaline-5,10-dione scaffold are studied as photoinitiators. These compounds are used in two- and three-component high-performance photoinitiating systems for the free radical polymerization of trimethylolpropane triacrylate (TMPTA) and polyethylene glycol diacrylate (PEGDA) under sunlight. Remarkably, the conversion of TMPTA can reach ≈60% within 20s, while PEGDA attains a 96% conversion within 90s. To delve into the intricate chemical mechanisms governing the polymerization, an array of analytical techniques is employed. Specifically, UV-vis absorption and fluorescence spectroscopy, steady-state photolysis, stability experiments, fluorescence quenching experiments, cyclic voltammetry, and electron spin resonance spin trapping (ESR-ST) experiments, collectively contribute to a comprehensive understanding of the photochemical mechanisms. Photoinitiation capacities of these systems are determined using real-time Fourier transformed infrared spectroscopy (RT-FTIR). Of particular interest is the revelation that, owing to the superior initiation ability of these dyes, high-resolution 3D patterns can be manufactured by direct laser write (DLW) technology and 3D printing. This underscores the efficient initiation of free radical polymerization processes by the newly developed dyes under both artificial and natural light sources, presenting an avenue for energy-saving, and environmentally friendly polymerization conditions.

Designing magnetic catalysts based on gold nanoparticles supported by ethylenediamine tetraacetic acid functionalized amino‐modified poly(N‐isopropyl acrylamide) for reduction of nitro compounds in water

AbstractA novel smart catalyst was developed with amino‐modified thermo‐responsive poly(N‐isopropyl acrylamide) (PNIPAM) grafts on silica‐coated magnetic nanoparticles using the conventional free radical polymerization process. By this methodology, the polymer was successfully grafted mainly onto silica‐modified iron oxide nanoparticles (Fe3O4@Si). The PNIPAM‐grafted Fe3O4@Si was then subjected to ethylenediamine treatment to produce the amino‐functionalized support (Fe3O4@Si@PNIPAM‐NH2), which was subsequently modified with carboxyl functional groups by using EDTA (ethylenediaminetetraacetic acid) to create Fe3O4@Si@PNIPAM‐NH2‐EDTA. Au nanoparticles were then decorated on this support through its two amines and four carboxylates. Different methods were used to study this novel catalyst, including inductively coupled plasma, Fourier transport infrared spectroscopy, TGA, dynamic light scattering, SEM, energy‐dispersive X‐ray analysis, vibrating sample magnetometry, XRD and elemental CHN analysis. The reduction of several aryl‐nitro derivatives demonstrated a significant catalytic activity for the as‐synthesized gold catalyst (Fe3O4@Si@PNIPAM‐NH2‐EDTA‐Au). The Au catalyst can be successfully removed from the reaction components using a magnetic field and used again in eight successive reduction reactions without significant gold leaching and loss of catalytic activity. © 2024 Society of Industrial Chemistry.

Revealing the photoredox potential of azulene derivatives as panchromatic photoinitiators in various light-initiated polymerization processes

Herein, the application of previously unknown azulene derivatives as effective panchromatic photosensitizers in the visible light range in the initiation of light-induced cationic and free-radical polymerization processes was investigated.

N,N-Dimethylaminoethyl methacrylate-based core/shell microgels loaded with silver nanoparticles for catalysis.

In this work, poly(styrene)@poly(N-isopropylmethacrylamide-co-2-(N,N-dimethyl)aminoethyl methacrylate [p(sty)@p(NIPMAM-DMAEMA)] core/shell microgel particles were produced by a two-step free-radical precipitation polymerization process. Ag nanoparticles were successfully embedded inside the sieves of a crosslinked network by using silver nitrate as the precursor salt and NaBH4 as the reductant. The synthesized pure and hybrid microgels were analyzed by various characterization tools, including Fourier transform infrared (FTIR) and UV-visible (UV-vis) spectroscopies, transmission electron microscopy (TEM) and dynamic light scattering (DLS). Results indicate the successful fabrication of spherical silver nanoparticles with diameters ranging from 10 to 15 nm within the sieves of the poly(styrene)@poly(N-isopropylmethacrylamide-co-2-(N,N-dimethyl)aminoethyl methacrylate) core/shell microgels, which have a hydrodynamic diameter of 155 ± 25 nm. The Ag nanomaterial exhibited long-term stability in the p(sty)@p(NIPMAM-DMAEMA) system due to the strong donor-acceptor relationship between the lone pair of the amide moiety in the polymer microgels and the Ag nanomaterial. The catalytic activity of the Ag-p(sty)@p(NIPMAM-DMAEMA) material was determined by performing the catalytic reduction of p-nitrophenol (4-NPh) as a model reaction under diverse concentrations of the catalyst. UV-vis spectrophotometry was used to check the progress of the reaction. The apparent rate constant (k app) was measured by applying the pseudo-first-order kinetics model. It was observed that k app increased with increasing catalyst dose, demonstrating occurrence of the reaction on the surface of the catalyst.

Structured polymer dispersant for efficient phthalocyanine blue dispersion and color paste preparation

AbstractTo overcome challenges in pigment dispersion, especially for difficult‐to‐disperse pigments like phthalocyanine blue, the structure of dispersants has been studied in recent years. Herein, we present the development and performance evaluation of a structured polymer dispersant for efficient dispersion of phthalocyanine blue and color paste preparation. The dispersant was synthesized using a two‐step free radical polymerization process, allowing precise control over its structure. The study investigates the impact of key factors on dispersion, including the molecular weight of the hydrophilic long‐chain poly(ethylene glycol) monomethyl ether (MPEG), the ratio of anchoring groups styrene (St) and dimethylaminoethyl methacrylate (DMAEMA), and the dispersant dosage. Optimal stability was achieved with MPEG‐400 as the hydrophilic long chain and a St:DMAEMA ratio of 1:1, along with a MPEG‐400AA:AA ratio of 0.5:1 at 2000 r min−1. At a dispersant dosage of 25%, the particle size of the color paste measured 340 nm, with viscosity reaching 600 mPa·s. The structured dispersant effectively synergized spatial potential resistance and electrostatic effects to achieve stable pigment dispersion. These findings offer promising prospects for advancing dispersant technologies, with implications for improving color‐based applications across various industries, such as paints, coatings, and inks.

Dextrin‐graft‐poly(2‐dimethylamino ethyl acrylate‐co‐2‐acrylamido‐2‐methyl propane sulfonic acid) polymer: A potential adsorbent for the fast removal of nitrophenols from aqueous medium

AbstractA graft copolymer is synthesized by grafting a mixture of 2‐(dimethylamino) ethyl acrylate (DMAEA) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) monomers onto the dextrin, polysaccharide backbone via free radical polymerization process using potassium peroxydisulfate (KPS) as radical initiator in aqueous phase. Various characterization techniques like 1H and 13C NMR, FT‐IR, SEM, EDAX, and XRD analysis are used to characterize the copolymer. The polymer is used as an adsorbent for the removal of nitrophenols namely ortho‐nitrophenol (ONP), para‐nitrophenol (PNP), and 2,4‐ dinitrophenol (DNP) from their water solutions. Adsorption dynamics, kinetics, isotherms, and thermodynamics are studied. The maximum nitrophenol adsorption occurs at time 80 min, temperature 45°C, pH 3.5 (DNP), and 4.5 (ONP and PNP), polymer dose 30 mg/L. The nitrophenol adsorption data are well‐fitted with the Langmuir isotherm model with maximum adsorption capacity () 215.26 mg g−1 for ONP, 223.60 mg g−1 for PNP, and 288.24 mg g−1 for DNP. The equilibrium kinetics follow pseudo‐second‐order kinetic model. Thermodynamic values unfold that the following nitrophenol adsorption onto the polymer surface is spontaneous and endothermic in nature. The value of Gibb's free energy for the nitrophenol adsorption is in the range of −6.5 to −9.5 kJ mol−1. The preferential nitrophenol adsorption by the copolymer is followed in the order ONP<PNP<DNP.

Synthesis, Characterization, Optical and Thermal Properties of P(NVC-co-BZMA) Copolymer and Its ZnO Composites

Recent studies have paid particular attention to polymer-nanoparticle composite materials considering they have a number of interesting properties, which include optical, thermal, electrical, and others (Reyna-Gonzalez et al., 2009; Yakuphanoglu et al., 2010). In this study, a free radical polymerization process was used to create a copolymer of N-vinylcarbazole (NVC) and benzyl methacrylate (BZMA) at 25–75 mol% each. The procedure was conducted at 70°C with azobisisobutyronitrile (AIBN) acting as the initiator. Nano zinc oxide powders were then added to composites at three different ratios of 5%, 10%, and 15% weight of the copolymer. In order to better understand the structures of the P(NVC-co-BZMA) and its composites, FT-IR, 1H NMR, and UV spectroscopic techniques were also implemented. The optical characteristics of both the pure copolymer and its composites were examined. In the visible region, the composite containing 15% nano ZnO had the highest optical absorbance value. Additionally, the thermal behaviours of the composites and copolymers were analysed.

Spectroscopic investigations of solvent assisted Li-ion transport decoupled from polymer in a gel polymer electrolyte

We present here a gel polymer electrolyte, where the Li+-ion transport is completely decoupled from the polymer host solvation and dynamics. A free-standing gel polymer electrolyte with a high volume content (nearly 60%) of xM LiTFSI in G4 (tetraglyme) (x = 1–7; Li+:G4 = 0.2–1.5) liquid electrolyte confined inside the PAN (polyacrylonitrile)-PEGMEMA [poly (ethylene glycol) methyl ether methacrylate oligomer] based polymer matrix is synthesized using a one-pot free radical polymerization process. For LiTFSI concentrations, x = 1–7 (Li+:G4 = 0.2–1.5), Raman and vibrational spectroscopies reveal that like in the liquid electrolyte, the designed gel polymer electrolytes (GPEs) also show direct coordination of Li+-ions with the tetraglyme leading to the formation of [Li(G4)]+. Coupled with the spectroscopic studies, impedance and nuclear magnetic resonance investigations also show that the ion transport is independent of the polymer segmental motion and is governed by the solvated species {[Li(G4)]+}, very similar to the scenario in ionic liquids. As a result, the magnitude of ionic conductivity and activation energies of the gel polymer electrolyte are very similar to that of the liquid electrolyte. The Li+-ion transport number for the GPE varied from 0.44 (x = 1) to 0.5 (x = 7) with the maximum being 0.52 at x = 5.

Temperature Controlled Mechanical Reinforcement of Polyacrylate Films Containing Nematic Liquid Crystals.

This investigation reports on the thermomechanical properties of Poly-tripropyleneglycoldiacrylate (Poly-TPGDA)/liquid crystal (LC) blends, developed via free radical polymerization processes, which are induced by Electron Beam (EB) and Ultraviolet (UV) radiation. The EB-cured Poly-TPGDA network exhibits a higher glass transition temperature (Tg), a higher tensile storage, and Young moduli than the corresponding UV-cured sample, indicating a lower elasticity and a shorter distance between the two adjacent crosslinking points. Above Tg of Poly-TPGDA/LC blends, the LC behaves as a plasticizing agent, whereas, for EB-cured networks, at temperatures below Tg, the LC shows a strong temperature dependence on the storage tensile modulus: the LC reinforces the polymer due to the presence of nano-sized phase separated glassy LC domains, confirmed by electron microscopy observations. In the case of the UV-cured TPGDA/LC system, the plasticizing effect of the LC remains dominant in both the whole composition and the temperature ranges explored. The rubber elasticity and Tg of Poly-TPGDA/LC films were investigated using mechanical measurements.

Environmentally adaptable hydrogel electrolyte with the triple interpenetrating network in the flexible zinc-ion battery with ultralong stability

With the increasing development of wearable electronic devices, the stabilities of the flexible battery are in great demand. However, the rapid capacity degradation and the limits of the traditional aqueous electrolyte in cold environmental condition still retards the practical application of the aqueous zinc ion batteries (ZIBs). Herein, a polyacrylamide/carboxymethyl cellulose/gelatin (PCG) hydrogel electrolyte with triple interpenetrating network was fabricated by an integrated physical crosslinking and free-radical polymerization process. Benefitting from its hierarchical porous structure, the PCG hydrogel electrolyte exhibits the stable mechanical compression deformation. The integrated cross-linked networks with abundant hydrogen bonds and high electrolyte salt prevent the crystallization of water, contributing to broadening its operating temperature (from −20 °C to room temperature). Therefore, the PCG electrolyte cannot only promise the highly reversible Zn2+ insertion/extraction, but also accelerate ion transfer in electrochemical process. As a result, the PCG-based ZIBs with magnesium vanadium oxide deliver a high capacity of 382.7 mAh g−1 and good cycling stability (10000 cycles at 0 °C). Besides, the assembled flexible ZIBs also exhibit a good capacity retention under various bending states. This unique strategy of hydrogel electrolyte provides new insights for flexible ZIBs with superior cycling stability.

Highly Stretchable, Tough, and Self-Recoverable Cationic Guar Gum-Based Hydrogels for Flexible Sensors

Stretchable and tough conductive hydrogels have attracted much attention in flexible sensing electronics. However, most existing conductive hydrogels have poor strain and strength or unsatisfactory recovery capability, which cannot satisfy the requirements for stretchable electronics. In this study, a type of hybrid ionic-covalent guar hydroxypropyltrimonium chloride (cationic guar gum, CGG)-based DN hydrogel with PAM covalent and CGG-CO32– or CGG-SO42– ionic networks via a free radical polymerization and soaking process was developed to prepare high-performance strain sensors. The existence of salt ions in the CGG-based hydrogel not only induces the formation of noncovalent cross-linking points, endowing the hydrogel high mechanical performance, but also gives the hydrogel high ionic conductivity. Consequently, the obtained hybrid DN hydrogels show high tensile strength (>1.2 MPa), large elongation (>1200%), high toughness, good conductivity, and rapid self-recovery property. Significantly, by simply controlling the soaking duration, we tailored the mechanics of the hybrid DN hydrogels. As demonstrated, this hydrogel-based sensor exhibits good sensitivity, large strain sensing capability, high durability, and could detect various human motions. Our study opens up a horizon in the preparation and regulation of cationic guar gum-based hydrogels for applications in high-performance flexible sensors.

Molecular imprinted polymer for tramadol: Absorption and drug release studies

AbstractSmart polymeric matrices based on 2‐vinyl pyridine (2‐VPY) and three different crosslinkers: ethylene glycol dimethacrylate (EGDMA), divinylbenzene (DVB), and trimethylolpropane trimethacrylate (TMPTMA) were prepared either by the imprinting technique of the tramadol molecule or conventionally by the free radical polymerization process. The polymers were used as sorbent materials for tramadol from its solutions. The polymers prepared by the imprinting technique demonstrated superior absorption of tramadol molecules than those prepared by the conventional method. The two sorbent materials constructed from TMPTMA, regardless of the method, achieved the highest absorption capacity compared with those prepared from EGDMA or DVB. It was found that loaded imprinted polymer released more tramadol than loaded nonimprinted polymer in all media. In the acidic medium, the protonation of the nitrogen atom in the pyridine ring ionized the chains and expanded the loaded pores leading to the rapid release over the neutral and alkaline media. Additionally, the isothermal studies of MIP3 and NIP3 were extremely fitted to Freundlich adsorption and the (D–R) isotherm, respectively, while the kinetic studies of both sorbents were fitted to the pseudo‐second‐order model.

Polyethylene glycol-based phase change materials with high photothermal conversion efficiency and shape stability in an aqueous environment for solar water heater

The development of composite phase change materials (PCM) with high photothermal conversion capability can effectively improve solar energy utilization. However, composite PCM loses the ability to encapsulate PCM in an aqueous/oil phase environment, limiting the practical scope of PCM applications. In our work, the composites stabilized in the aqueous phase were prepared using a free radical polymerization process. Composites have a high loading rate (85.1–89.0 wt%), high thermal conductivity (204% higher than PEG), high energy storage density (138.6 J/g), and high photothermal conversion efficiency (93.3%). Since PEG is encapsulated inside the structure during the polymerization of PAAAM, it can still encapsulate PEG even in the aqueous phase. Utilizing the heat storage characteristics of PEG and the high photothermal conversion characteristics of RHTC, composites can be used in solar water heater systems, reducing the operating costs and showing great application potential in aqueous phase environment.