Reactivity Ratios R1 Research Articles

Synthesis of Antimicrobial and Antioxidant Zinc Oxide Hydrogel for Drug Delivery Applications

A novel and simple method was used to synthesize antimicrobial and antioxidant porous (N-tert-butylacrylamide-co-N-vinylpyrrolidone) zinc oxide hydrogel via free radical copolymerization. The hydrogel was characterized by NMR, XRD, and SEM. Thermodynamic properties of the hydrogel were described quantitatively by the Flory-Rehner method. The results indicate that the synthesized hydrogel exhibits strong antioxidant activity, making it a potential candidate for use in preventing degenerative diseases. The antimicrobial tests showed that the hydrogel could inhibit the growth of Gram-positive and Gram-negative bacteria, as well as some pathogenic bacteria and fungi. The inhibition zones ranged from 10 to 15 mm for bacteria and from 5.2 to 9.1 mm for fungi. The reactivity ratio r1 × r2 equal to 1 confirmed ideal copolymerization showed the composition of the copolymer and the comonomer feed are same. The hydrogel's structure and reactivity are significant for constructing effective delivery systems for specific applications. Optimizing the monomer proportion could enhance hydrogel efficiency and release behavior. The hydrogel's water solubility, non-toxicity, and antioxidant properties suggest it could be safe and effective throughout the drug delivery process, contributing both passive and reactive targeting functions.

Synthesis and Study of Thermoresponsive Amphiphilic Copolymers via RAFT Polymerization.

Synthesis and study of well-defined thermoresponsive amphiphilic copolymers with various compositions were reported. Kinetics of the reversible addition-fragmentation chain transfer (RAFT) (co)polymerization of styrene (St) and oligo(ethylene glycol) methyl ether methacrylate (PEO5MEMA) was studied by size exclusion chromatography (SEC) and 1H NMR spectroscopy, which allows calculating not only (co)polymerization parameters but also gives valuable information on RAFT (co)polymerization kinetics, process control, and chain propagation. Molecular weight Mn and dispersity Đ of the copolymers were determined by SEC with triple detection. The detailed investigation of styrene and PEO5MEMA (co)polymerization showed that both monomers prefer cross-polymerization due to their low reactivity ratios (r1 < 1, r2 < 1); therefore, the distribution of monomeric units across the copolymer chain of p(St-co-PEO5MEMA) with various compositions is almost ideally statistical or azeotropic. The thermoresponsive properties of p(St-co-PEO5MEMA) copolymers in aqueous solutions as a function of different hydrophilic/hydrophobic substituent ratios were evaluated by measuring the changes in hydrodynamic parameters under applied temperature using the dynamic light scattering method (DLS).

Synthesis and evaluation of new cationic polymeric surfactant based on N-phthalimidomethyl methacrylate

In our previous work N-phthalimidomethyl methacrylate (NPMMA) monomer was prepared through the reaction of N-hydroxymethyl phthalimide with methacrylic acid in the presence of N, N-dicyclohexylcarbodiimide (DCCI) as a condensing agent. Then a new series of copolymers containing imidazole have been synthesized through the reaction of NPMMA monomer with 1-vinylimidazole (VIM) in the presence of benzoyl peroxide as initiator. The copolymer composition was determined by 1H NMR spectroscopy and the values of monomer reactivity ratio (r1= 0.756, r2= 1.033, and r1r2= 0.781) were calculated through Fineman Ross and Kelen-Tudos methods. Conversion of copolymers to surfactants was achieved through quaternization of the imidazole nitrogen with dimethyl sulphate. The chemical structure of the produced monomer, copolymers, co-polymeric surfactants was confirmed by spectroscopic tools. The surface properties included surface tension, foaming power, emulsion stability, critical micelle concentration (CMC) have been measured in aqueous medium by traditional procedures. Also the different air/ water interface parameters including effectiveness (πcmc), efficiency (Pc20), maximum surface excess (Γmax) and minimum surface area (Amin) were also recorded. Moreover, the biodegradability for these cationic surfactants has been investigated and their D % was ranged from 67 to 100 %.

Copolymerization of N-Tert-Butylacrylamide (NTB) and 7-Methacryloyloxy-4-Methyl coumarin (MAMC): Synthesis and characterization

Copolymers of various feed ratio of N-tert-butylacrylamide (NTB) and 7-methacryloyloxy-4-methyl coumarin (MAMC) were prepared by free radical solution polymerization in DMF at 70 °C using AIBN as an initiator. Synthesised copolymers were characterized and copolymer compositions were obtained by 1H NMR analysis data. By using Fineman-Ross, Kelen-Tudos and extended Kelen-Tudos methods, monomer reactivity ratios (r1 and r2) were calculated. Mean sequence lengths of the copolymers were estimated from monomer reactivity ratio (r1 and r2) values. Thermal characterizations of the copolymers were carried out using thermogravimetric analysis. The antimicrobial effects of obtained copolymers were also tested on various bacteria, and fungi.

Synthesis, Characterization and Reactivity Ratios of Poly Phenyl Acrylamide-Co-Methyl Methacrylate

The monomer phenyl acrylamide was synthesized by reacting acrylamide with chloro benzene in the presence of pyridine. Copolymer of phenyl acrylamide (PAM) with methyl methacrylate (MMA) was synthesized by free radical technique using dimethylsulfoxide (DMSO) as solvent and benzoyl peroxide (BPO) as initiator. The overall conversion was kept low (≤ 15% wt/wt) for all studies copolymers samples. The synthesized copolymers were characterized using fourier transform infrared spectroscopy (FT-IR), and their thermal properties were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The copolymers compositions were determined by elemental analysis. The monomer reactivity ratios have been calculated by linearization methods proposed by Kelen-Tudos and Fineman-Ross. The derived reactivity ratios (r1, r2) for (PAM-co-MMA) are: (0.03, 0.593). The microstructure of copolymers and sequence distribution of monomers in the copolymers were calculated by statistical method based on the average reactivity ratios and found that these values are in agreement with the derived reactivity ratios. Copolymers of PAM with MMA formed alternating copolymers.

One-Step Ring Opening Metathesis Block-Like Copolymers and their Compositional Analysis by a Novel Retardation Technique.

Using a one-step synthetic route for block copolymers avoids the repeated addition of monomers to the polymerization mixture, which can easily lead to contamination and, therefore, to the unwanted termination of chain growth. For this purpose, monomers (M1-M5) with different steric hindrances and different propagation rates are explored. Copolymerization of M1 (propagating rapidly) with M2 (propagating slowly), M1 with M3 (propagating extremely slowly) and M4 (propagating rapidly) with M5 (propagating slowly) yielded diblock-like copolymers using Grubbs' first (G1) or third generation catalyst (G3). The monomer consumption was followed by 1 H NMR spectroscopy, which revealed vastly different reactivity ratios for M1 and M2. In the case of M1 and M3, we observed the highest difference in reactivity ratios (r1 =324 and r2 =0.003) ever reported for a copolymerization method. A triblock-like copolymer was also synthesized using G3 by first allowing the consumption of the mixture of M1 and M2 and then adding M1 again. In addition, in order to measure the fast reaction rates of the G3 catalyst with M1, we report a novel retardation technique based on an unusual reversible G3 Fischer-carbene to G3 benzylidene/alkylidene transformation.

One‐Step Ring Opening Metathesis Block‐Like Copolymers and their Compositional Analysis by a Novel Retardation Technique

AbstractUsing a one‐step synthetic route for block copolymers avoids the repeated addition of monomers to the polymerization mixture, which can easily lead to contamination and, therefore, to the unwanted termination of chain growth. For this purpose, monomers (M1–M5) with different steric hindrances and different propagation rates are explored. Copolymerization of M1 (propagating rapidly) with M2 (propagating slowly), M1 with M3 (propagating extremely slowly) and M4 (propagating rapidly) with M5 (propagating slowly) yielded diblock‐like copolymers using Grubbs’ first (G1) or third generation catalyst (G3). The monomer consumption was followed by 1H NMR spectroscopy, which revealed vastly different reactivity ratios for M1 and M2. In the case of M1 and M3, we observed the highest difference in reactivity ratios (r1=324 and r2=0.003) ever reported for a copolymerization method. A triblock‐like copolymer was also synthesized using G3 by first allowing the consumption of the mixture of M1 and M2 and then adding M1 again. In addition, in order to measure the fast reaction rates of the G3 catalyst with M1, we report a novel retardation technique based on an unusual reversible G3 Fischer‐carbene to G3 benzylidene/alkylidene transformation.

Study of Copolymerization Acrylamide with Methyl Methacrylate

Copolymer of acrylamide (AM) with methyl methacrylate (MMA) was synthesized by free radical technique using dimethylsulfoxide (DMSO) as solvent and benzoyl peroxide (BPO) as initiator. The overall conversion was kept low (≤ 15% wt/wt) for all studies copolymer’s samples. The synthesized copolymers were characterized using fourier transform infrared spectroscopy (FT-IR), and their thermal properties were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The copolymers compositions were determined by elemental analysis. The monomer reactivity ratios have been calculated by linearization methods proposed by Kelen-Tudos and Fineman-Ross. The derived reactivity ratios (r1, r2) for (AM-co-MMA) are: (0.03, 0.593). The microstructure of copolymers and sequence distribution of monomers in the copolymers were calculated by statistical method based on the average reactivity ratios and found that these values are in agreement with the derived reactivity ratios. Copolymers of AM with MMA formed alternating copolymers. Keywords: Acrylamide; Methyl methacrylate; Reactivity ratios; Sequence distribution

Studying Reactivity Relationships of Copolymers N-naphthylacrylamide with (Acrylicacid and Methylacrylate)

The organation ⁄monomer N-naphthylacrylamide (NAA) was prepared; subsequently the synthesized monomer was successfully copolymerized with acrylicacid (AA) and methylacrylate (MA) by free radical technique using dry benzene as solvent and benzoyl peroxide (BPO) as initiator. The overall conversion was kept low (≤ 10% wt/wt) for all studies copolymers samples. The synthesized monomer and copolymers were characterized using Fourier transform infrared spectroscopy (FT-IR), and their thermal properties were studied by DSC and TGA. The copolymers compositions were determined by elemental analysis. Kelen-Tudes and Finmman-Ross graphical procedures were employed to determine the monomers reactivity ratios. The derived reactivity ratios (r1, r2) are: (0.048, 0.687) for (NAA-co-AA) and (0.066, 0.346) for (NAA-co-MA). Based on the average reactivity ratios, sequence distribution of monomers in the copolymers and the microstructure of copolymers were calculated by statistical method and found that these values are in agreement with the derived reactivity ratios.

Studying Reactivity Relationships of Copolymers N-naphthylacrylamide with (Acrylicacid and Methylacrylate)

The organation ⁄monomer N-naphthylacrylamide (NAA) was prepared; subsequently the synthesized monomer was successfully copolymerized with acrylicacid (AA) and methylacrylate (MA) by free radical technique using dry benzene as solvent and benzoyl peroxide (BPO) as initiator. The overall conversion was kept low (≤ 10% wt/wt) for all studies copolymers samples. The synthesized monomer and copolymers were characterized using Fourier transform infrared spectroscopy (FT-IR), and their thermal properties were studied by DSC and TGA. The copolymers compositions were determined by elemental analysis. Kelen-Tudes and Finmman-Ross graphical procedures were employed to determine the monomers reactivity ratios. The derived reactivity ratios (r1, r2) are: (0.048, 0.687) for (NAA-co-AA) and (0.066, 0.346) for (NAA-co-MA). Based on the average reactivity ratios, sequence distribution of monomers in the copolymers and the microstructure of copolymers were calculated by statistical method and found that these values are in agreement with the derived reactivity ratios.

Methacrylate copolymers and their composites with nano-CdS: synthesis, characterization, thermal behavior, and antimicrobial properties

Homo- and copolymers of 2-(N-phthalimido)ethyl methacrylate (NPEMA) and p-chlorophenyl methacrylate (PCPMA) were prepared in N,N-dimethyl formamide (DMF) solution at 70 °C using 2,2-azo-bisisobutyronitrile (AIBN) as initiator. The nano-CdS-doped polymer composite of NPEMA and PCPMA was prepared via in situ technique. The homo- and copolymers of NPEMA and PCPMA were characterized using FT-IR spectroscopy and gel permeation chromatography (GPC). The polymer nano composites were characterized using FT-IR spectroscopy, X-ray diffraction, and transmission electron microscopy. The reactivity ratios (r1 and r2) were obtained from the various linear graphical methods. The values of r1 (NPEMA) = 0.55 and r2 (PCPMA) = 1.30 were found from the same graphical methods. The copolymer microstructures were found from the mean sequence length, run number, and dyad fraction. Thermal behavior of polymers and polymer nano composites under nitrogen atmosphere was studied. The activation energies of neat polymers were varied in the range of 56–85 kJ/mol, while 28–56 kJ/mol energies were found for nano-CdS-doped polymer composites. The thermodynamic parameters of thermal degradation were also obtained. Kinetic and thermodynamic parameters were confirming the stability of the neat polymers than polymer nano composites. The polymers were assessed on different microorganisms for obtaining the antimicrobial properties. Overall, the polymers permit 10–52, 20–58, and 18–56% growth of bacteria, fungi, and yeast, respectively.

Synthesis, characterization, microstructure determination, thermal studies of poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate)

ABSTRACTSynthesis of Poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate) terpolymer using azobisisobutyronitrile in 1,4-dioxan is described. The polymers with different composition were synthesized and characterized using FTIR, 1HNMR, 13NMR, TGA and DSC techniques. The monomer-monomer interactions were studied using Finemann-Ross and Kelen-Tudos methods by calculating the reactivity ratio. The reactivity ratio r1 and r2 with respect to methyl methacrylate and N-vinylpyrrolidone-maleic anhydride complexomer are found to be 6.05 and 0.06 respectively. The study showed methyl methacrylate have higher reactivity than N-vinyl-2-pyrrolidone-maleic anhydride complex, i.e., the terpolymer contained methyl methacrylate in higher ratio. The thermal stability of poly (N-vinyl pyrrolidone-maleic anhydride-methyl methacrylate) was 165°C and the glass transition temperature was found to increase from 153°C to 182°C as MMA concentration increase. The studies indicate the activity of the polymer to inhibit bacterial growth is very poor.

Correlation of reactivity ratios, transition-metal salts and ester hydrolysis to radical polymerization of electron-deficient comonomers with 2-(N,N-dimethylamino)ethyl methacrylate as the inimer

The radical copolymerization of 2-(N,N-dimethylamino)ethyl methacrylate (DMAEMA, M1) as the inimer and electron-deficient monomers (M2, including methyl methacrylate (MMA), acrylamide (AAm) and N,N-dimethylacrylamide (DMAAm)) with transition-metal salts (such as copperII and ironIII) as the oxidizing agent was correlated to their reactivity ratios (r1 and r2), counterions to transition-metal salts and ester hydrolysis of DMAEMA with an objective to obtain high-molecular weight (MW) branched polymers. As r1 ≈ r2 ≈ 1.0, primary chain initiation occurred even at high MMA conversion during CuSO4-DMAEMA redox-initiated radical polymerization of MMA, and thus the polymerization failed to form high-MW branched PMMA free from linear analogues. As r1 > 1.0 > r2, DMAEMA was preferentially converted into -DMAEMA- units during Fe(NO3)3-DMAEMA redox-initiated aqueous radical polymerization of AAm/DMAAm, but N,N-dimethylaminoethanol formed via hydrolysis led to lower-MW chains. Under optimal conditions with minimum hydrolysis, FeCl3-DMAEMA redox-initiated aqueous radical polymerization of DMAAm proceeded via redox-initiated reverse atom transfer radical polymerization (ATRP) generating DMAEMA-terminated chains with a carbon-chloride terminal. FeII-catalyzed self-condensing ATRP led to high-MW branched PDMAAm even under aerobic conditions.

Accurate density functional theory (DFT) protocol for screening and designing chain transfer and branching agents for LDPE systems

This work emphasizes the importance of considering multiple reaction pathways when estimating the rate parameters for free radical polymerization using DFT.

Visualization of Bivariate Sequence Length–Chain Length Distribution in Free Radical Copolymerization

Copolymer properties and processability depend on copolymer microstructure, i.e., copolymer composition and monomer unit arrangements along the copolymer chains. To predict the ultimate properties of copolymers, one needs complete information on the length and position of sequences of each monomer type in every chain. A versatile kinetic Monte Carlo code is developed and applied for the simulation of typical free radical copolymerizations. The code allows explicit monitoring of every growing chain during the course and at the end of polymerization, can account for comonomer systems of any arbitrary reactivity ratios (r1 and r2) over the full range of monomer composition. Meanwhile, it eliminates the need for solving arrays of differential equations arising from deterministic modeling approaches. Since the code virtually synthesizes billions of copolymer molecules and keeps in storage information on each and every copolymer chain in the system, it allows for detailed statistical analysis. The simulator visualizes the bivariate sequence length–chain length distribution for typical copolymerization systems and examples with: r1 &lt; 1 and r2 &lt; 1; r1 &gt; 1 and r2 &lt; 1; (r1 × r2) = 1; and r1 = r2 = 1, and is also applied successfully to an experimental scenario described in the literature.

Copolymerization of Partly Incompatible Monomers: An Insight from Computer Simulations

In this work we used dissipative particle dynamics simulations to study the copolymerization process in the presence of spatial heterogeneities caused by incompatibility between polymerizing monomers. The polymer sequence details as well as the resulting system spatial structure in the case if phase segregation occurs during the chain growth can be predicted using the method. We performed the model verification with the available literature data on styrene-acrylic acid copolymerization in the bulk and a very good agreement between experimental and simulated data for both chain average composition and triad fractions was observed. Next, we studied the system properties for a model symmetric reaction process with the reactivity ratios r1 = r2 = 0.5 at different compositions and Flory-Huggins parameters \c{hi}. We found that the system average copolymer "composition-feed" curve does not depend on the \c{hi}-value, but there are significant changes in the copolymer sequences caused by the density fluctuations. Finally, we investigated the formation of gradient copolymers during living styrene-acrylic acid copolymerization at a highly asymmetrical feed composition.

Tuning the spectral, thermal and fluorescent properties of conjugated polymers via random copolymerization of hole transporting monomers

Effect of copolymerization on the fluorescent properties of polycarbazole and poly(o-phenylenediamine).

Synthesis and Free Radical Copolymerization of a Vinyl Monomer from Soybean Oil

A one-step method that converts soybean oil into (acryloylamino)ethyl soyate, a new vinyl monomer of free radical polymerization, was developed. The synthesized monomer combines a vinyl double bond (acryloyl functional group) and nonconjugated (isolated) double bonds of fatty acids. The double bond of the acryloyl group is reactive in a free radical chain polymerization that yields linear macromolecules containing isolated double bonds in side chains. Monomer reactivity ratios (r1, r2) in copolymerization of the new soybean oil-based acrylic monomer (SBA) with styrene, methyl methacrylate, and vinyl acetate, as well as the Q–e parameters of the SBA, were determined. The obtained results indicate that copolymerization can be described with the classical Mayo–Lewis equation. In terms of polymerizability, the SBA can be classified as an acrylic monomer. The double bonds of the fatty acid chains remain mainly unaffected during the free radical polymerization. The remaining unsaturated fragments in the side ch...

Copolymerization of 2-Ethylhexyl Acrylate and D-Limonene

The bulk free radical copolymerization of D-limonene and 2-ethylhexyl acrylate (EHA) was conducted at 80°C using benzoyl peroxide (BPO) as initiator. Low conversion experiments were conducted to estimate the copolymer reactivity ratios. The reactivity ratios r1 = 6.896 and r2 = 0.032 (1 = EHA, 2 = d-limonene) were obtained using a non-linear, error-in-variables method with the RREVM computer program. High conversion experiments were performed and revealed that a degradative chain transfer mechanism for D-limonene dominated the polymerization.

Synthesis of ultrahigh-molecular-weight ethylene-1-hexene copolymers with high hexene content via living polymerization with fluorinated bis(phenoxy-imine) titanium(IV).

The fluorinated FI-Ti catalyst bis[N-(3-propylsalicylidene)-pentafluoroanilinato] titanium(IV) dichloride (PFI) combined with dried methylaluminoxane (dMAO) is investigated for ethylene/1-hexene copolymerization at 50 °C under atmospheric pressure. The reaction shows good livingness and has a high activity at high [H]/[E] molar ratios up to 14. Ultrahigh molecular weight (>1.4 × 10(6) g mol(-1) ) copolymers with high 1-hexene content (>25 mol%) are prepared. Kinetic parameters of the copolymerization with PFI are determined. The first-order Markov statistics applies and the product of the reactivity ratios r1 r2 is close to 1, giving random unit distributions.