Polymerization Of Acrylic Monomers Research Articles

Synthesis and rheological properties of carboxymethyl cellulose modified polyacrylic acid thickener with high electrolyte resistance

Herein, a method for preparing highly resistant electrolyte thickeners by introducing supramolecular interactions (multiple hydrogen bonds and electrostatic interactions) and chemical crosslinking during the polymerization of acrylic monomers has been proposed. The hydroxyl group on the carboxymethyl cellulose (CMC) unit provides multiple hydrogen bonds for the thickener structure, the carboxyl group on the polyacrylic acid (PAA) molecular chain provides electrostatic interactions for the thickener structure, and the crosslinking agent MBA forms a chemical network structure in the CMC-PAA molecular chain. The synergistic formation of multiple dynamic crosslinking points through the above effects is beneficial for improving the electrolyte resistance of CMC-PAA thickeners. The shift of the carbonyl characteristic peak on the FTIR spectrum confirms the existence of hydrogen bonding interactions between PAA and CMC. The viscosity retention rates of CMC-PAA thickener in tap water and saltwater electrolytes were 97.01% and 53.22%, respectively, exceeding our previously reported hydrophobic modified polyacrylic acid thickener, confirmed that the introduction of hydrogen bonds inhibits the contraction of molecular chains. The fitting analysis of the rheological properties of the color paste shows that the sisko model has high fitting accuracy of the color paste. In addition, CMC-PAA has excellent thermal stability and water-holding properties, which can ensure the contour clarity of subsequent inkjet printed fabrics. This study provides a new method for improving the electrolyte resistance of polyacrylic acid thickeners.

Durable and organic-solvent-free anti-icing coating fabricated from polyacrylate grafted with PDMS

Traditional anti-icing coatings suffer from issues of non-durability in anti-icing performance and the generation of volatile organic compounds during the coating process. In this study, durable and organic-solvent-free anti-icing coatings were prepared based on polyacrylate grafted with hydrophobic polydimethylsiloxane (PAC-PDMSx). The PAC-PDMSx is prepared by emulsion polymerization of acrylate monomer and acrylate mono-terminated polydimethylsiloxane (M-PDMS), without the involvement of organic solvents. The higher the content of M-PDMS, the better the anti-icing performance of the PAC-PDMSx coating. Meanwhile, the anti-icing performance of the coating demonstrates good durability during the icing/deicing cycle and environmental aging. The ice adhesion strength of PAC-PDMSx is reduced to 11 kPa after 100 icing/de-icing cycles and 17 kPa after simulated environmental aging for 504 hours, while the initial value is 25 kPa. This study provides a promising environmentally-friendly passive de-icing coating with durable anti-icing performance for practical applications.

Carbazole-fused coumarin bis oxime esters (CCOBOEs) as efficient photoinitiators of polymerization for 3D printing with 405 nm LED

In this research, the innovative design and successful synthesis of two visible light photoinitiators, namely CCOBOE0 and CCOBOE1, have been confirmed through nuclear magnetic resonance (NMR) and mass spectrometry (MS). Both compounds exhibit strong absorption properties at 385, 405 and 450 nm, and FT-IR analyses have substantiated the ability of CCOBOE1 to initiate the polymerization of a trifunctional acrylate monomer (TMPTA) under these three light sources. The optimal conditions for maximizing the photoinitiation potential of CCOBOE1 were determined to be at a concentration of 2 × 10−5 mol.g−1 and under 405 nm LED irradiation. Photolysis experiments, theoretical calculations, detection of CO2 absorption peaks, and ESR experiments have all confirmed the generation of methyl radicals by CCOBOE1. Utilizing the identified optimal conditions, a “XYZ” pattern with a thickness of 963 μm and a 3D-object were successfully obtained via direct laser write (DLW) and digital light processing (DLP) 3D-printing upon irradiation at 405 nm. Additionally, differential scanning calorimetry (DSC) analyses demonstrated the promising performance of CCOBOE1 in initiating the thermal polymerization of acrylate monomers. In summary, the difunctional CCOBOE1 showed outstanding performance in both photo-initiation and thermal initiation of acrylate monomers. It provides a novel direction for the development of novel OXEs with dual activation modes.

Modeling of Electrochemical Impedance of Fuel Cell Based on Novel Nanocomposite Membrane

The new hybrid composite materials for PEM fuel cell were synthesized by the UV polymerization of acrylic monomers (acrylonitrile, acrylic acid, ethylene glycol dimethacrylate) and a sulfo aromatic monomer, i.e., sodium styrene sulfonate, and the tetraethoxysilane/3-methacryloxypropyltrimethoxysilane-based sol–gel system. By means of X-ray spectroscopy, the fractal structure of the obtained materials was characterized. Proton conductivity and viscoelasticity of the obtained materials were determined depending on the content of the inorganic component in nanocomposites. Based on impedance studies, an equivalent scheme is proposed that successfully describes the proton conductivity in the synthesized composite’s electrolyte membranes.

Structure-properties relationships of defined CNF single-networks crosslinked by telechelic PEGs

The high structural anisotropy and colloidal stability of cellulose nanofibrils' enable the creation of self-standing fibrillar hydrogel networks at very low solid contents. Adding methacrylate moieties on the surface of TEMPO oxidized CNFs allows the formation of more robust covalently crosslinked networks by free radical polymerization of acrylic monomers, exploiting the mechanical properties of these networks more efficiently. This technique yields strong and elastic networks but with an undefined network structure. In this work, we use acrylate-capped telechelic polymers derived from the step-growth polymerization of PEG diacrylate and dithiothreitol to crosslink methacrylated TEMPO-oxidized cellulose nanofibrils (MATO CNF). This combination resulted in flexible and strong hydrogels, as observed through rheological studies, compression and tensile loading. The structure and mechanical properties of these hydrogel networks were found to depend on the dimensions of the CNFs and polymer crosslinkers. The structure of the networks and the role of individual components were evaluated with SAXS (Small-Angle X-ray Scattering) and photo-rheology. A thorough understanding of hybrid CNF/polymer networks and how to best exploit the capacity of these networks enable further advancement of cellulose-based materials for applications in packaging, soft robotics, and biomedical engineering.

A single-component LED excited enone photoinitiator for colorless and transparent antibacterial film preparation

Photoinitiators (PIs), as the key substances for photopolymerized antibacterial film (PAF), affect the cure rate and color of PAF. Herein, two enone dyes were designed and synthesized by a facile approach. Among the candidates, BDO1 has demonstrated the ability to initiate polymerization of acrylate monomers as single-component PI with the advantages of low mobility, outstanding photobleaching, excellent cytocompatibility, and suitability for light emitting diode (LED) light sources above 365 nm. Taking BDOs as examples, a novel method based on theoretical calculations aiming to assess the potential of enone molecules as single-component PIs was proposed. Finally, under the initiation of BDO1, tannic acid was photopolymerized to a colorless and transparent antibacterial film with high antibacterial ability, which indicated that BDO1 was expected to be used in environmentally friendly PAF.

New ketoxime ester-amine photoinitiator based on charge transfer complex for free radical LED polymerization

Recently, visible-light polymerization has received increasing attention because of the development of LED sources and the innovation of photopolymerization technology, which is derived from different strategies to design photoinitiating systems such as the construction of D-π-A-type photoinitiators or the use of up-conversion nanoparticles. However, the association of electron donor and acceptor molecules to form a charge-transfer complex (CTC) for polymerization has rarely been reported. Hence, a ketoxime ester (PFO) with a pentafluorophenone ring as an electron-defect acceptor has been designed and synthesized as a photosensitizer. Our investigation results showed that CTCs could be formed by associating PFO with amines that contain electron-rich rings and process a better absorption property in the visible-light region than PFO. Moreover, the two kinds of free radicals with high photoactivity were generated from CTCs via photochemical transformation, such as intermolecular charge transfer and α-cleavage, which can play a role in initiating the polymerization of acrylate monomers, and the efficiency of initiating polymerization is higher than that of PFO alone under LED@395–425 nm irradiation.

Safety assessment for nail cosmetics: Framework for the estimation of systemic exposure through the nail plate

All cosmetics products, including nail care products, must be evaluated for their safety. The assessment of systemic exposure is a key component of the safety assessment. However, data on the exposure, especially via ungual route (nail plate) are limited. Based on the physicochemical properties of human nails and permeability data of topical onychomycosis drugs, the nail plate is considered a good barrier to chemicals. We examine factors impacting penetration of nail care ingredients through the nail plate, including properties of the nails of the ingredients and formulations. The molecular weight, vapor pressure, logP, water solubility, and keratin binding, as well as formulations properties e.g., polymerization of acrylate monomers are considered important factors affecting penetration. To estimate systemic exposure of nail care ingredients through the nail plate, a standardized framework is applied that quantifies the impacts of these properties on penetration with an adjustment factor for each of these influencing properties. All the adjustment factors are then consolidated to derive an integrated adjustment factor which can be used for calculation of the systemic exposure dose for the ingredient. Several case studies are presented to reflect how this framework can be used in the exposure assessment for nail cosmetic products.

Systematic studies on polyacrylates containing side‐chain hydrogen bonding units: Significant effects of the pendant functions on thermal behaviors and solubility of polymers

AbstractThe synthesis of polyacrylates containing various pendant hydrogen bonding or non‐hydrogen bonding functions and the effects of side‐chain functions on their physical properties are described. The polyacrylates possessing urea, urethane, N‐substituted urea, or carbonate groups are prepared by the free radical polymerization of acrylate monomers possessing the corresponding functional groups. The presence of stronger hydrogen bonding interactions both in bulk and solutions of a highly polar solvent such as dimethyl sulfoxide (DMSO) is supported by the infrared (IR) spectra, whereas the urethane‐based polyacrylate does not exhibit the interaction in the solution. The presence of the stronger hydrogen bonding interactions of the urea unit is discussed by the IR and nuclear magnetic resonance spectra and the density functional theory calculations of the corresponding model compounds. The solubility in organic solvents and the glass transition temperature (Tg) of polymers are also dependent on the structure of the pendant groups. Polar aprotic solvents such as DMSO can only dissolve the urea‐based polyacrylate, while the other polymers are soluble in a much wider range of solvents such as tetrahydrofuran. The urea‐based polyacrylate shows the highest Tg among the polymers studied owing to the presence of plural hydrogen bonding sites in the urea groups.

Grafting Starch with Acrylic Acid and Fenton's Initiator: The Selectivity Challenge.

Through the graft polymerization of acrylic monomers onto starch, materials with interesting new properties can be synthesized. Fenton's chemistry, Fe2+/H2O2, is considered to be attractive for the initiation of graft polymerization with the monomer acrylic acid since it is cheap and reacts quickly at ambient conditions and should therefore be easy to scale up. However, the selectivity of the grafting versus the homopolymerization reaction poses a challenge with this monomer and this type of initiator. In the present review paper, we investigate why data from the literature on grafting systems with other monomers and initiation systems tend to show higher graft selectivity. A scheme is presented, based on reaction engineering principles, that supports an explanation for these observed differences. It is found that more selective activation of starch is a factor, but perhaps even more important is a low monomer-to-starch ratio at the starting sites of graft reactions. Since water is the most common solvent, monomers that are less water-soluble have an advantage in this respect. Based on the proposed scheme, methods to improve the graft selectivity with Fenton's initiator and acrylic acid are evaluated. Most promising appears to be a method of gradual monomer dosage. With gelatinized cassava starch in a batch reactor, both the grafting percentage (17 => 29%) and graft selectivity (18 => 31%) could be improved. This can be considered a principal breakthrough. Still, more research and development would be needed to refine the method and to implement the idea in a continuous reactor at a larger scale.

Precise recognition and efficient recovery of Pd(II) from high-level liquid waste by a novel aminothiazole-functionalized silica-based adsorbent

Efficient recognition, separation and recovery of palladium from high-level liquid waste (HLLW) not only helps the safe, green and environmentally friendly disposal of nuclear waste, but also is an essential important supplement to overcome the growing shortage of natural palladium resources. Herein, a novel silica-based functional adsorbent named 2AT-SiAaC was prepared by a two-step method, i.e., grafting of 2-aminothiazole (2AT) via the amidated reaction after in-situ polymerization of acrylic monomers on porous silica. SEM, EDS, TG-DSC, BET and PXRD all proved the successful preparation of 2AT-SiAaC, and it exhibited ultrahigh adsorption selectivity for Pd(II) (Kd (distribution coefficient) ≥ 10,344.2 mL/g, SFPd/M (separation factor) ≥ 613.7), fast adsorption kinetics with short equilibrium time (t ≤ 1 h) and good adsorption capacity (Q ≥ 62.1 mg Pd/g). The dynamic column experiments shows that 2AT-SiAaC achieved efficiently separation of Pd(II) from simulated HLLW, and the enrichment coefficients (C/C0) of Pd(II) was as high as about 14 with the recovery rate nearly 99.9% and basically kept the same performance in three adsorption-desorption column cycle experiments. The adsorption mechanism was analyzed by FT-IR, XPS and DFT calculations, and the ultrahigh selectivity of 2AT-SiAaC was attributed to the preferred affinity of the soft N-donor atoms in 2AT for Pd(II). NO3− ions participated in the adsorption reaction to keep charge balance, and the frontier orbital electron density distribution diagram shows the charge transfer in the process of material preparation and adsorption. To sum up, 2AT-SiAaC adsorbent provided a new insight for precise recognition and efficient separation of Pd(II) from HLLW.

SYNTHESIS OF COPOLYMERS OF STEARYLMETHACRYLATE AND STEARYLACRYLATE WITH N-SUBSTITUTED ACRYLAMIDES IN THE PRESENCE OF REVERSIBLE CHAIN TRANSFER AGENTS AND STUDY OF THEIR EFFECT ON THE LOW-TEMPERATURE PROPERTIES OF DIESEL FUEL

The features of copolymerization of stearylacrylate (SA) and stearylmethacrylate with N-isopropylacrylamide and N,N-dimethylacrylamide in the presence of dibenzyltrithiocarbonate and 2-cyanoisopropyldodecyltrithiocarbonate as agents of reversible chain transfer have been studied. The choice of agents of reversible chain transfer (RAFT-agents) is due to the fact that sulfur-containing compounds with cyanoisopropyl radicals are most effective in the polymerization of methacrylic monomers, while benzyltrithiocarbonates are more active in the polymerization of acrylic monomers, as well as styrene and acrylonitrile. It has been established that polymerization of stearyl methacrylate (SMA) in the presence of RAFT-agents proceeds without a gel effect up to a high conversion. At the same time, although polystеarylmethacrylate samples are characterized by relatively high values of polydispersity coefficients (Mn/Mw) for controlled radical polymerization processes, they are nevertheless somewhat lower than for polymers of similar conversion synthesized in the absence of chain transfer agents. It has been shown that the process of copolymerization of stearyl acrylate and stearylmethacrylate with N-isopropylacrylamide and N,N-dimethylacrylamide in the presence of dibenzyltrithiocarbonate and 2-cyanoisopropyldodecyltrithiocarbonate proceeds without gelation to high conversions. The synthesized copolymers are characterized by a relatively narrow molecular weight distribution: the polydispersity coefficients of polymer samples vary from 1.18 to 1.57 in the case of using N-isopropylacrylamide and from 1.21 to 1.47 when using N,N-dimethylacrylamide as a comonomer to higher alkyl acrylates, which is typical for processes of radical polymerization proceeding in a controlled manner. At the same time, the synthesized copolymers exhibit a significant depressant effect when they are introduced into diesel fuel at a concentration of 1600 ppm. It has been established that copolymers of stearylmethacrylate and stearylacrylate with polar nitrogen-containing monomers have a more effective effect on the low-temperature properties of diesel fuel than homopolymers of stearylmethacrylate and stearylacrylate. At the same time, additives based on copolymers of stearylmethacrylate with N-isopropylacrylamide with a composition of 70/30 mol.% and stearylacrylate with N-isopropylacrylamide with a composition of 20/80 mol.% had the most significant effect on the low-temperature characteristics of the fuel.

Triphenylamine-substituted BODIPY dye based photoinitiators for free radical and cationic photopolymerization under visible LED irradiation and application in 3D printing

Until now the photopolymerization process is largely dependent on the hazardous UV or near UV light irradiation. Herein this work, a series of boron dipyrromethene (BODIPY) derivatives substituted by electron-donating triphenylamine moiety on different positions were introduced and investigated thoroughly. Markedly, their photoinitiation abilities under mild conditions, e.g. visible LEDs irradiation and room temperature, were examined for the first time. In combination with an iodonium salt and an amine as the co-initiators, these BODIPY dyes could form three-component photoinitiating systems (PISs) for the purpose to initiate both the free radical polymerization of acrylate monomers and cationic polymerization of epoxy monomers. Interestingly, under the irradiation of LED@405 nm, LED@530 nm or LED@660 nm, some of these BODIPYs-based PISs could conduct high monomeric conversion and rapid photopolymerization rates, as reflected by the relevant photopolymerization kinetics. Then the notable photochemical reactivity of these BODIPY dyes was examined by both steady state photolysis and fluorescence quenching experiments, and theoretical calculation was also performed on them in details. Finally, photocuring 3D printing technique was applied to the acrylate/epoxy mixture resin, as the result the BODIPYs-based PISs demonstrated great potential to fabricate truly three-dimensional objects in macroscopic scale with excellent spatial resolution.

Using the Polymerization of Acrylic Monomers for the Treatment and Conservation of a Historical Piece in the Agricultural Museum, Dokki “An Applied Study”

Using the Polymerization of Acrylic Monomers for the Treatment and Conservation of a Historical Piece in the Agricultural Museum, Dokki “An Applied Study”

Vitamin B12 Derivative Enables Cobalt-Catalyzed Atom Transfer Radical Polymerization.

Advances in controlled radical polymerizations by cobalt complexes have primarily taken advantage of the reactivity of cobalt as a persistent radical to reversibly deactivate propagating chains by forming a carbon-cobalt bond. However, cobalt-mediated radical polymerizations require stoichiometric ratios of a cobalt complex, deterring its utility in synthesizing well-defined polymers. Here, we developed a strategy to use cobalt as a catalyst to control radical polymerizations via halogen atom transfer with alkyl halide initiators. Using a modified, hydrophobic analogue of vitamin B12 (heptamethyl ester cobyrinate) as a cobalt precatalyst, we controlled the polymerization of acrylate monomers. The polymerization efficiency of the cobalt catalyst was significantly improved by additional bromide anions, which enhanced the deactivation of propagating radicals yielding polymers with dispersity values <1.2 using catalyst concentrations as low as 5 mol %. We anticipate that the development of cobalt catalysis in atom transfer radical polymerization will enable new opportunities in designing catalytic systems for the controlled synthesis of polymers.

Regulating copolymer architecture using photoiniferter polymerization to direct composite morphology

Due to mild conditions and straightforward synthetic routes, photoiniferter polymerization has received increasing use as a facile method for preparation of polymers with highly controlled structure. However, low quantum yields inherent to thiocarbonylthio species result in polymerization speeds that are considerably slower than traditional controlled radical polymerization techniques. To improve polymerization speed while maintaining high level control, it is critical to understand relationships between reaction parameters and ultimate polymer structure. In this work, initiating light intensity, reactant concentration, and monomer pendant groups were manipulated in the photoiniferter polymerization of acrylate monomers to explore the effect of these conditions on reaction kinetics and molecular weight control. Polymerization rate of n-butyl acrylate was significantly enhanced by increasing light intensity rivaling speeds of conventional thermally initiated RAFT polymerization while enabling more precise control over molecular weight. Interestingly, photoiniferter rate asymptotically approached saturation at relatively high light intensities. Moreover, degradation of trithiocarbonate species occurred at greater intensities, ultimately resulting in moderate increases in molecular weight. Increased reactant concentration enabled faster rates with bulk polymerization, possibly due to reduced macro radical mobility and termination. Additionally, comparing photoiniferter polymerization of methyl acrylate and hydroxyethyl acrylate showed that greater polarity considerably enhanced polymerization speeds. Finally, the utility of precisely controlling polymer structure was demonstrated by synthesizing and incorporating a series of amphiphilic block copolymers with increasing molecular weight into a photocurable epoxy resin. The well-defined block copolymer structures enabled controllable phase separation and thermomechanical properties in epoxy composites. This work showed that photoiniferter polymerization speeds could be significantly enhanced using elementary reaction conditions, and that these conditions enable facile production of well-defined copolymers allowing tailored composite morphology and properties.

Synthesis and characterization of water-borne vanillin derived copolymers containing dynamic imine cross-links

In the effort toward the production of circular plastics, the use of lignin-derived aromatic building blocks such as vanillin is interesting due to their functionality. Nonetheless, the water-borne emulsion polymerization of acrylic monomers derived from vanillin is still lacking. Vanillin can be readily functionalized with a methacrylate group for the radical polymerization to yield polymers containing functional aldehyde side groups. The functionality can be exploited via imine formation to produce vitrimers, a class of cross-linked recyclable polymers. Besides recycling, synthesis via a water-borne emulsion polymerization is desired to reduce the negative contribution of solvents on the environment and health. In the present work, polymethacrylates based on 2-(methacryloyloxy)ethyl vanillin and 2-octyl acrylate were synthesized via a emulsion polymerization approach to produce a water-borne latex. A latex with a small particle size (49 nm) and solid content of 31 wt% was obtained. For comparative purposes, a similar polymer was synthesized via solution polymerization. Both polymers were cross-linked using a multifunctional amine to produce recyclable imine vitrimers. This research investigates the unique combination of water-borne synthesis and vitrimer polymers, and therefore contributes to future development of vitrimer latex products such as coatings and films.

Unimolecular Benzodioxole-based Photoinitiators for Free Radical and Cationic Photopolymerization Under LED Light Irradiation

Compared to amines as coinitiators applied in photopolymerization, benzodioxole derivatives exhibit similar reactivity but less yellowing and lower toxicity. In this paper, a series of unimolecular type II photoinitiators, containing coumarins as chromophores and benzodioxoles as coinitiators, were synthesized. The substituents with different electron donating/withdrawing abilities were designed for systematical investigation of structure-property relationship. Under LED irradiation, the novel photoinitiators can induce not only free radical polymerization of acrylate monomers, but also cationic polymerization of epoxy monomers via radical promoted cationic polymerization mechanism.

Anti-freezing dual-network hydrogels with high-strength, self-adhesive and strain-sensitive for flexible sensors

Hydrogels as flexible sensor have attracted significant attention due to its conductivity, stretchability and flexibility. However, it is still a great challenge to prepare hydrogels that simultaneously possess high strength, anti-fatigue, self-adhesion, and anti-freezing. Herein, a multifunctional dual-network hydrogel was prepared by in situ polymerization of acrylic monomer in chitosan chains, and coordinated with aluminum chloride and glycerol. Based on chain entanglement, hydrogen bonding and coordination interactions, this dual-network hydrogel exhibited excellent mechanical properties, good fatigue resistance, and excellent adhesion performance. It can be used as a strain sensor for its stable conductivity and high sensitivity, which could monitor both large human motions and subtle motions. Due to the presence of glycerol, the hydrogel showed outstanding freezing resistance and still kept flexible and conductive even at low temperatures (−20 °C). This hydrogel can be applied as a flexible wearable sensor for monitoring human motion in extreme low-temperature condition.

N-naphthalimide ester derivatives as Type Ⅰ photoinitiators for LED photopolymerization

In this study, a series of N-naphthalimide ester derivatives (noted NPIE1-NPIE9) with different substituents were designed as visible light photoinitiators (PIs). These structures exhibited good light absorption properties in the visible range. Photoinitiation abilities of NPIEs were evaluated upon exposure to a light-emitting diode at 405 nm. All the structures demonstrated good performances in free radical polymerization of acrylate monomers. Markedly, the function conversion for acrylate monomers in the presence of NPIE1 was higher than that of the benchmark PI diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO). Upon exposure to a light-emitting diode at 455 nm, NPIE1 could also initiate the polymerization of acrylate monomers effectively, i.e., the benchmark photoinitiator (TPO) was not efficient for these long irradiation wavelengths. Through the calculations of the N–O bond dissociation energy and the excited state energy, the cleavage of the N–O bond from the singlet state proved to be favorable. Interestingly, CO2 was detected during the polymerization experiments, which indicated that there was a decarboxylation reaction during irradiation. Based on the obtained results, a mechanism of Type Ⅰ PI behavior can be proposed. Due to the good performance, NPIE1 was successfully used in 3D printing experiments. In addition, high thermal stability of NPIEs in monomers was found. This can be a great improvement for elaborating stable formulations.