Radical Solution Copolymerization Research Articles

Analytical Steady-State Model for the Free Radical Solution Copolymerization of Acrylonitrile and Vinyl Acetate and Their Charge-Transfer Complex in a Continuous Stirred Tank Reactor

In this study, a mathematical model of the copolymerization of AN-VA in a continuous stirred tank reactor (CSTR) was developed considering charge-transfer complexes (CTCs). CTC formation between acrylonitrile (AN) and vinyl acetate (VA) was demonstrated using UV-VIS spectrophotometry and molecular orbital theory. The rate constants and equilibrium constants of the complexes were calculated from a model of the simultaneous participation of complexes and free monomers and the molar ratio method. Furthermore, the participation of CTCs in propagation was included because of their high reactivity. All the simultaneous equations defined to analyze the reactor parameters were analytically solved, and the results of the model were in terms of operative variables such as monomer conversion, average molecular weight, and the mole fraction of monomer 2 (i.e., VA) in the polymer formed. The results of the predictions of the developed model were compared with the experimental data for validation. This prediction was also compared with the reactor model solution without considering the CTC, which showed deviations that were more significant than those of the CTC model. These results represent a quantitative way to analyze the order of magnitude of the impact of the formation of the complexes in the analyzed polymerization system.

Hydrogels Based on Chitosan and Sodium Alginate with Shape Memory Effect

Hydrogels based on chitosan derivatives, sodium alginate with acrylamide and acrylic acid were obtained by free radical solution copolymerization method in the presence of ammonium persulfate as initiator and urotropin and N,N methylene bisacrylamide as crosslinking agents. The formation of hydrogels was proved by extraction and IR spectroscopy. It is shown that hydrogels are able to fix the temporary form in iron (III) chloride solutions and reclaim it in solutions of ascorbic acid in less than 2 hours. Hydrogels based on sodium alginate have the best physical-mechanical characteristics compared with chitosan-based - the strength reaches 0.7 MPa and 0.11 MPa, the elasticity modulus is 1.02 MPa and 0.17 MPa at 65% deformation, correspondingly.

COPOLYMERIZATION OF UNSATURATED OLIGOESTERS MODIFIED WITH NITROGEN-CONTAINING COMPOUNDS WITH METHYL METHACRYLATE

In the present work, the kinetics of radical copolymerization in solution at the initial stages of polyglycol maleinate phthalates modified with nitrogen-containing compounds with methyl methacrylate in a ratio of 1:1 was studied. Cyclohexanone was used as a solvent, and benzoyl peroxide was used as an initiator. The study was carried out at temperatures of 50 and 60 °C by dilatometry using collapsible dilatometers and a centrifuge. 13 amine-containing compounds of different types were chosen as modifiers. Also, for comparison, the possibility of using amides and hydrazines as modifiers was checked. Polycondensation was carried out in an oil bath at 175 °C and with vigorous stirring with water withdrawal until a constant acid number was reached. It is shown that the addition of 0.1 mol/l modifier during the polycondensation of a mixture of maleic and phthalic anhydrides with ethylene glycol makes it possible to obtain an unsaturated oligoester, for which the temperature coefficient of the reaction of its copolymerization with methyl methacrylate is significantly reduced. This allows for non-isothermal curing to increase the volume of the copolymer block without the risk of overheating and destruction. Of the studied amines, para-aminoacetophenone turned out to be the most effective; its use as a modifier makes it possible to reduce the temperature coefficient of the reaction from 2.1 to 1.7. The rate of copolymerization at the initial stages for the studied modified systems decreases from 2 to 20 times. The results of the work allow us to propose a technology for the production of polymeric materials by molding them in blocks of much larger sizes than with the use of traditional unsaturated oligomers. Also, calculations were carried out according to a special technique and the maximum size of a copolymer block in the form of a cylinder was determined, in which the height is equal to the radius, which can be obtained by forming it in a non-isothermal mode in a thin layer form with convection air cooling and the maximum allowable temperature in the system is 90 °C. It is shown that the volume of such a block, when using some modified oligomers, increases significantly. Some physical and mechanical characteristics of the obtained copolymers with methyl methacrylate were determined, and it was shown that modification with nitrogen-containing compounds does not improve or worsen the studied characteristics.

Synthesis of amphiphilic molecular brushes by solution radical copolymerization of oligoethylene glycol and oligopropylene glycol methacrylates

The regularities of radical copolymerization of methoxyoligo(ethylene glycol)methacrylate (MOEGM) with an ethoxylation degree of 11 and methoxyoligo(propylene glycol)methacrylate (MOPGM) with a propoxylation degree of 6 or 10 in toluene solutions were determined. The copolymers formed at low degrees of conversion are enriched with ethoxylated ether units in both pairs of monomers. The relative activities of the comonomers determined by the Fineman-Ross methods are in the range of 1.36–1.88 (MOEGM) and 0.56–0.92 (MOPGM). It has been established that the activity of MOPGM decreases with an increase in the length of the oligopropylene glycol chain.

Measurement and Modeling of Semi-Batch Solution Radical Copolymerization of N-tert-Butyl Acrylamide with Methyl Acrylate in Ethanol/Water.

The synthetic polymer industry is transitioning from the use of organic solvents to aqueous media in order to reduce environmental impact. However, with radical polymerization kinetics affected by hydrogen-bonding solvents, there is limited information regarding the use of water as a solvent for sparingly soluble monomers. Thus, in this paper, the radical polymerization of methyl acrylate (MA) and N-tert-butylacrylamide (t-BuAAm) is studied in water and ethanol (EtOH), as the copolymer product is of commercial interest. A series of semi-batch reactions are conducted under a range of operating conditions (i.e., reaction temperature, solvent-to-monomer ratio, and comonomer composition) to demonstrate that the copolymer can be successfully synthesized without significant drifts in product molar masses or composition. The experiments provide additional data to probe the influence of the solvent on the polymerization rate and copolymer properties, as the low monomer concentration maintained under starved-feed operation leads to a solvent-to-monomer ratio different from that in a batch system. A model that captures the influence of backbiting and solvent effects on rate, previously developed and tested against batch polymerizations, also provides an excellent description of semi-batch operation, validating the set of mechanisms and kinetic coefficients developed to represent the system.

Preparation and Properties of Nanoclay Reinforced High‐Performance Functional Poly(Itaconic Anhydride‐co‐Acrylamide) Nanomaterials

AbstractIn this work, poly(itaconic anhydride‐co‐acrylamide) copolymer was synthesized by free radical solution copolymerization and poly(itaconic anhydride‐co‐acrylamide)/nanoclay nanocomposites were prepared by in situ interlamellar copolymerization with three different loading of nanoclay. Intercalation and formation of nanostructures were clarified by spectroscopic techniques. The interaction/compatibility between nanoclay and the copolymer was verified by following the characteristic bands of nanoclay and functional groups in the ATR‐FTIR spectra. The increase in d‐spacing between silicate layers in nanocomposites was determined from XRD analysis. The thermal and viscoelastic properties of nanomaterials and the effect of simultaneous addition of nanofiller were evaluated by thermogravimetric and dynamic mechanical analysis. It was observed that nanocomposites reinforced with nanoclay had higher thermal stability than pristine poly(itaconic anhydride‐co‐acrylamide) and thermal stability increased proportionally with amount of nanoclay loaded. The improvement effect of the incorporated nanoclay on the storage modulus was observed at higher temperature values for the nanocomposite loaded with 4 % nanoclay.

Oil aerated flocs formation assisted by a flocculant for heavy oil produced water treatment

Air flotation cyclone is a potentially efficient method to improve the treatment efficiency of heavy oil produced water in offshore fields. For its practical application, it is of great significance to develop a flocculant that can flocculate air bubbles and oil droplets together to form oil aerated flocs. In this paper, a novel flocculant capable of rapidly forming oil aerated flocs was prepared and the formation conditions and mechanism of oil aerated flocs were investigated. Firstly, copolymer (PDAMPE-NH) was synthesized by free radical solution copolymerization of N-(3-dimethylaminopropyl) methacrylamide (DPM), diallylamine (DAA) and block polyether macromonomer (PEP) as the monomers. Then, the molecular weight of PDAMPE-NH was increased by using polyethylene glycol diacrylate (PEG-DA) as a chain extender. Finally, the target flocculant DA was obtained by protonating the tertiary amine group in the copolymer with formic acid. The protonated tertiary amine group in DA can capture oil droplets, and the polyether group in DA can capture air bubbles. When the DA dosage was 500 mg/L and bubble size was in range of 20 μm to100 μm, the oil aerated flocs were formed, and the oil content of heavy oil produced water reduced from 7250 mg/L to less than 100 mg/L within 90 s. Microscopic observation found that there were three stages for oil aerated flocs formation and the formation of oil-coated bubbles was the key step. The reported results can provide a reference for the fast treatment of heavy oil produced water in offshore fields.

Chitosan Graft Copolymers with N-Vinylimidazole as Promising Matrices for Immobilization of Bromelain, Ficin, and Papain.

This work aims to synthesize graft copolymers of chitosan and N-vinylimidazole (VI) with different compositions to be used as matrices for the immobilization of cysteine proteases—bromelain, ficin, and papain. The copolymers are synthesized by free radical solution copolymerization with a potassium persulfate-sodium metabisulfite blend initiator. The copolymers have a relatively high frequency of grafting and yields. All the synthesized graft copolymers are water-soluble, and their solutions are characterized by DLS and laser Doppler microelectrophoresis. The copolymers are self-assembled in aqueous solutions, and they have a cationic nature and pH-sensitivity correlating to the VI content. The FTIR data demonstrate that synthesized graft copolymers conjugate cysteine proteases. The synthesized copolymer adsorbs more enzyme macromolecules compared to non-modified chitosan with the same molecular weight. The proteolytic activity of the immobilized enzymes is increased up to 100% compared to native ones. The immobilized ficin retains up to 97% of the initial activity after a one-day incubation, the immobilized bromelain retains 69% of activity after a 3-day incubation, and the immobilized papain retains 57% of the initial activity after a 7-day incubation. Therefore, the synthesized copolymers can be used as matrices for the immobilization of bromelain, ficin, and papain.

Free radical solution copolymerization of monomers of dissimilar reactivity - influencing chemical composition distribution and properties of copolymers of methyl methacrylate and N-vinyl imidazole by varying monomer feeding profiles

Copolymerization is one way of influencing the properties of polymers and the outcome of copolymerization between vinyl monomers is dependent on the reactivity ratios between the monomers. Incorporation of polar monomers into copolymers offer many benefits. In this regard, N-Vinyl imidazole (NVI) carries much significance as a comonomer. NVI is a specialty monomer. The high polarity and planarity of NVI can impart many beneficial characteristics upon copolymerization with other vinyl monomers. However, its unfavourable reactivity ratios with other vinyl monomers prevent the facile incorporation of NVI in the copolymers. In this work, a semi-continuous solution polymerization is employed with the help of software called Monomer Addition Profile (MAP) to predict the optimal addition profile of the more reactive monomer (methyl methacrylate) through an iterative approach in order to achieve uniform incorporation of less reactive comonomer in the copolymer chain. The predicted chemical composition distribution (CCD) of the copolymerization is used to determine the homogeneity of copolymers which is well supported by the glass transition temperature (Tg) of copolymers. Apart from the workflow of MAP, solubility characteristics of copolymers, microstructure and sequence length are also discussed in this article.

Radical copolymerization kinetics of N-tert-butyl acrylamide and methyl acrylate in polar media

Methyl acrylate/N-tert-butyl acrylamide solution radical copolymerization kinetics is well-represented by the terminal model in ethanol-rich mixtures with water, provided that the influence of solvent on homopropagation kinetics is considered.

Hydrolyzation-Triggered Ultralong Room-Temperature Phosphorescence in Biobased Nonconjugated Polymers.

Amorphous nonconjugated room-temperature phosphorescent (RTP) polymers have aroused ever-increasing attention. However, the variety of such polymers is still rare due to limited preparation strategies. Herein, we report a facile strategy to achieve ultralong RTP emission in biobased nonconjugated polymers through a hydrolyzation process. The investigated polymers are synthesized by free radical solution copolymerization using biomass methyl isoeugenol and maleic anhydride as monomers. Noticeably, the obtained polymers carry no conventional fluorescent units but can exhibit blue fluorescence. More interestingly, after hydrolysis in sodium hydroxide aqueous solution, the resulting hydrolyzed polymers emit both enhanced blue emission and persistent RTP (up to 400 ms) under air conditions, with reversible emission performance switched via the uptake and removal of water. Also worthy to be highlighted is that the emission can be remarkably regulated by the cations in carboxylate or the substituents on the benzene ring. The as-obtained polymers demonstrate potential applications in anticounterfeiting and information encryption.

An automated recipe generator for semi-batch solution radical copolymerization via comprehensive stochastic modeling and derivative-free algorithms

• Comprehensive stochastic modeling of semibatch starved-feed radical copolymerization. • Model used to optimize system while maintaining starved-feed features. • Nonlinear dosing strategy developed for monomer, comonomer, and initiator feeds. • New strategy experimentally assessed by measuring evolution of copolymer properties. • Strategy scaled-up to produce a uniform product while greatly reducing reaction time. Knowledge of the average composition and molecular weights of copolymers containing functional groups is often not enough to ensure product quality, as the distribution of the reactive moieties among the chains affects performance. This work couples a kinetic Monte Carlo model, previously verified as providing an accurate description of the semi-batch radical solution copolymerization of butyl methacrylate with 2-hydroxyethyl methacrylate under constant-feed higher-temperature conditions, with an optimization procedure designed to maintain the robust features of starved-feed operation (with no on-line measurements of reactant concentrations or polymer properties) while reducing batch time and keeping product properties at target values. The optimizer calculated piece-wise time-varying dosing strategies for monomer, comonomer, and initiator feeds that reduced reaction time by 75% while improving the uniformity of the product molecular weight, composition, and non-functional fraction. The strategy was successfully tested in a 1 L lab-reactor, and then scaled to a larger test system of 5 L to demonstrate the feasibility of significantly reducing the total reaction time while simultaneously improving the quality of the resin.

SYNTHESIS AND INVESTIGATION OF COPOLYMERS OF GLYCIDYLMETHACRYLATE AND COPPER COMPLEX METHYL PHEOPHORBIDE “A” IN SOLUTION

The actual direction in the field of creating new functional materials is a complex study of the influence of tetrapyrrole macroheterocyclic compounds on the processes of radical (co)polymerization with widely used monomers, as well as the development of a general approach to the synthesis and study of the properties of such polymer materials. Promising macroheterocyclic compounds are chlorophyll derivatives of various structures. For this purpose, by the method of solution radical copolymerization in toluene and tetrahydrofuran the copolymers of glycidylmethacrylate and copper complex of methylpheophorbide “a” of various compositions were obtained. Identification of the obtained copolymers and investigation of their structure and properties were performed using data from IR, NMR spectroscopy of compounds, elemental and chemical analysis methods. The synthesized copolymers are characterized by molecular-weight characteristics which were determined by gel-permeation chromatography. It was found that the introduction of a copper complex of methylpheophorbide “a” into the copolymer leads to a decrease in the copolymerization rate, the values of the molecular masses of copolymers and an increase in their polydispersity. The effect of solvents on the time of the copolymerization process and the molecular weight characteristics of copolymers is shown. The composition of the obtained copolymers was determined spectrophotometrically by the optical density of their solutions at the maximum of the first absorption band of the copper complex of methylfeoforbide “a”. Comparison of the intensity of bands in the IR spectra of copolymers of different compositions showed that the content of methylpheophorbid links in the polymer chain increases with the increase in the content of porphyrin in the polymerized mixture. The study of the influence of the nature of the solvent and its structural features on chemical reactions involving porphyrin derivatives allowed us to establish that from a thermodynamic point of view, the best solvent for porphyrinpolymers is toluene.

Deterministic Approach to Estimate Functionality of Chains Produced by Radical Copolymerization in the Presence of Secondary Reactions

Functional acrylic resins for the coatings and adhesives industry are often synthesized by radical solution copolymerization at high temperatures (>120 °C) using starved-feed semibatch operation. T...

PROPERTIES OF DILUTE SOLUTIONS OF COPOLYMERS OF GLYCIDYLMETHACRYLATE AND METHYLPHEOPHORBIDE «a» IN DIMETHYLFORMAMIDE

The study of the rheological properties of polymers, and also the establishment of quantitative dependencies, along with the problem of the relationship of molecular characteristics with the synthesis conditions, is an important scientific and practical task. The solution of this problem gives to predict the behavior of polymers, to develop and find the optimal modes and parameters of obtaining materials with predetermined properties. For a research of chemical interaction between macromolecules in solutions, the dilute solutions rheology of copolymers of glycidylmethacrylate and methylphaeophorbide “a” in dimethylformamide was studied. The study of dilute solutions of the corresponding copolymers was carried out by viscometric method in the temperature range of 20-35 ºC. Copolymers of glycidylmethacrylate and methylphaeophorbide “a” of different composition were obtained by radical copolymerization in solution. The synthesized copolymers are characterized by molecular-weight characteristics determined by gel-permeation chromatography. It is established that the solutions of the copolymers correspond to the systems with the lower critical temperature of dissolution. The belonging of the studied solutions to the systems with the lower critical dissolution temperature is confirmed by the dependence of the Huggins constant on the temperature. From the obtained results it follows that the ball of the macromolecule shrinks with increasing temperature. The influence of solution temperature, molecular weight and composition of copolymers on their interaction with the solvent, expressed quantitatively through the parameters of the characteristic viscosity, the Huggins constant, the mean-square distance between the ends of macromolecular chains, is shown. The mean-square distance between the ends of the chains of polymer in the solution was estimated by the equation of Flory-Fox. It is shown that for the studied copolymers the specific index decreases with increasing temperature. It was determined that the introduction of the porphyrin fragment into the structure of the polymer macromolecule retains the character of the interaction of the macromolecular tangle with the solvent.

Effect of Sodium Alginate Content in Acrylic Acid/Sodium Humate/Sodium Alginate Superabsorbent Hydrogel on Removal Capacity of MB and CV Dye by Adsorption

A series of (AAc/SH/NaAlg) superabsorbent hydrogels based on poly Acrylic acid (AAc), sodium humate (SH) and sodium alginate (NaAlg) were prepared by free radical solution copolymerization. The effect of sodium alginate was studied in a range of 20–66 wt%. Synthesized superabsorbent hydrogels (SAHs) were characterized by swelling behavior. Synthesized SAHs were tested as an adsorbent for MB and CV dyes. The binding capacity for MB and CV molecules were 367 mg/g/L and 359 mg/g/L at 380 mg/L respectively, for initial molecules concentration per gram of (AAc/SH/NaAlg) SAHs containing 50 wt% of NaAlg. The adsorption values obeyed Langmuir sorption Isotherm.

Modeling of Semibatch Solution Radical Copolymerization of Butyl Methacrylate and 2‐Hydroxyethyl Acrylate

AbstractNonfunctional monomer feedstocks containing alkyl meth(acrylate) components such as butyl acrylate (BA) and butyl methacrylate (BMA) are replaced or augmented with functional monomers such as 2‐hydroxyethyl methacrylate (HEMA) and 2‐hydroxyethyl acrylate (HEA) to produce reactive polymer chains of lowered molar mass for application in solvent‐borne automotive coatings. The introduction of such polar and functional reactants affects the radical copolymerization kinetics and introduces solvent dependencies. A series of BMA/HEA experiments are performed to determine the influence of these changing kinetic parameters under starved‐feed semibatch operating conditions. A comparison with BMA/BA copolymerizations shows that the influence of hydrogen bonding is small, with the semibatch system well controlled to HEA contents of up to 50 wt%. Thus, the experiments are well represented by a comprehensive generalized copolymerization model that considers relevant methacrylate and acrylate side‐reactions and uses the chain growth parameters measured in previous kinetic investigations.

Multifunctional crosslinkable itaconic acid copolymers for enzyme immobilization

UV-Crosslinkable itaconic copolymers are developed to provide new multifunctional materials for coatings which combine crosslinkable functionalities and the possibility to immobilize enzymes. The polymer-immobilized enzymes were used for water treatment to decompose persistent organic molecules. Introduction of suitable comonomers allows tailoring the mechanical and chemical properties for special applications. Copolymers containing MMA and itaconic anhydride were chosen because of the formation of long-term stable anhydride functionalities. These anhydride functionalities are employed to attach enzymes covalently. 4-Benzoylphenyl methacrylate is used as comonomer for UV-initiated crosslinking. Terpolymers are successfully obtained by radical copolymerization in solution. The copolymers are compared to poly(ethylene-alt-maleic anhydride) [P(EMA)] often used with respect to enzyme immobilization, activity and hydrolytic stability. The hydrolysis stability of the copolymers against water is studied by ATR-FTIR spectroscopy. Thin films are prepared on glass substrates in a layer-by-layer procedure by spin-coating. The layer formation is monitored by ATR-FTIR spectroscopy. UV-crosslinking of the copolymer films is performed taking the optimal irradiation dose that avoids polymer degradation. ATR-FTIR spectroscopy verifies the coupling reaction between amino groups of the enzyme and the anhydride groups on the surface of the crosslinked polymer film. The syringaldazine (4-hydroxy-3,5-dimethoxybenzaldehyde azine) test and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assay demonstrate that the immobilized enzymes maintain their activities. The functional copolymers showed a significant effect in reduction of persistent organic pollutants in contaminated waste water.

Synthesis and Complex Formation of Porphyrin Polymers on the Basis of Methyl Methacrylate

Copolymers of methyl methacrylate with various porphyrin monomers were prepared by radical copolymerization in solution. The yields, molecular weight characteristics of the copolymers and the molar content of porphyrin in the copolymers were determined. Copper and zinc complexes of the synthesized porphyrin polymers were obtained.

Dynamical modeling and experimental aspects of multi-responsive hydroxy-functional methacrylate-based gels with tunable swelling induced by multivalent ions

Novel materials displaying multi-responsive property were developed by forming crosslinked copolymer systems that exhibit distinct temperature, pH and salt-sensitivity independently. An investigation of the mechanical properties of a novel multi-responsive poly(hydroxypropyl methacrylate) (PHPMA)-based hydrogel system was carried out with two major objectives. First was to study the effect of various preparation conditions; reaction temperature, comonomer content on the elasticity as well as on the absorbency of resulting hydroxy-functional methacrylate-based gels and the second was to interpret their water uptake data by various kinetic models. Experiments were conducted to characterize the equilibrium swelling and temperature/pH-dependent phase transitions of PHPMA-based copolymeric gels prepared by radical crosslinking copolymerization in aqueous solution with tetraethyleneglycol dimethacrylate (TEGDMA) as crosslinker. The aqueous equilibrium swelling properties of PHPMA hydrogels and cryogels containing methacrylate-based comonomer were described using N,N-dimethylaminopropyl methacrylate (DMAEMA) having weakly basic cationic groups. For PHPMA-based copolymeric hydrogels, the scaling laws relating the optimum preparation conditions with the crosslinking density N and the swelling degree qv were derived. Dynamic kinetics profiles were evaluated to outline the swelling/deswelling response of the resulting hydrogels and cryogels which presents useful information when designing specific applications that pursue or require the absorption of pH-sensitive or ionic-strength-sensitive molecules.