Monomer Feed Composition Research Articles

Optimization, experimental and theoretical investigation of modified guar-gum and poly(acrylic acid) based smart hydrogel for controlled release applications in the agricultural field

A series of smart polymer hydrogels with good uptake and controlled release characteristics were synthesized free-radically by growing poly(acrylic acid) on allylated guar gum using ammonium persulfate as an initiator and trimethylolpropane triacrylate as the crosslinker. The synthesized hydrogels were evaluated using FT-IR and NMR for their structure, thermo-gravimetric analysis (TG) to measure thermal stability, and scanning electron microscopy (SEM) to analyze surface morphology and swellability by gravimetric method under different pH and temperature conditions. The soil moisture content and gel fractions were measured using gravimetric methods. Additionally, a theoretical investigation was also performed to assess the urea-holding capacity of the synthesized hydrogel matrix using density functional theory (DFT) calculations. The uptake study revealed that the hydrogel with optimized monomer feed composition absorbed 851 g/g of water, 78 % and 67 % of urea from 0.5 % and 1 % urea solutions respectively under ambient conditions. The release study showed that 56 and 47 % of absorbed urea were released over 15 days from the urea-loaded hydrogels (0.5 % and 1 % urea solutions respectively). The uptake mechanism obeyed the non-Fickian and first-order kinetics models. The experimental evaluation and DFT calculations conveyed that the synthesized hydrogel could act as a candidature matrix for the controlled release of water and fertilizer in the agricultural field.

A versatile method for facile and reliable synthesis of colloidal particles with a size and composition gradient

Abstract Colloidal particles play a pivotal role in numerous applications across various disciplines, many of which necessitate precise control over particle size and size distribution. Seeded growth reactions have been established as effective methods for reproducibly accessing tailor-made particles. However, conventional batch-wise syntheses only yield discrete particle sizes. With the increasing focus on complex structures in current research, there is a demand for innovative and adaptable techniques to produce colloidal particles with precise sizes and size distributions. The Controlled Emulsion Extraction Process (CrEEP) is capable of addressing this challenge. Here, we present in detail how this synthesis works and demonstrate its reliability and versatility. Our approach exploits the time-dependent particle growth and enables accessing dispersions of controlled particle size distributions. We highlight these possibilities through a variation of the monomer feed and feed composition, resulting in gradual changes in both size and glass transition temperature, respectively. Beyond its application to polymer particles, CrEEP can be seamlessly extended to other seeded-growth mechanisms, such as the silica Stöber synthesis. Consequently, the Controlled Extraction Stöber Process (CrESP) similarly yields a size gradient, showcasing the generality of this synthetic advancement. Graphical abstract

Investigating the potential of degradable poly(vinyl acetate) copolymer microparticles for encapsulation and in vitro release studies

Poly(vinyl acetate) is a well-known polymer synthesized through the free radical polymerization of vinyl acetate (VAc) monomer. However, enhancing the degradability of this polymer is best achieved by copolymerizing cyclic ketene acetal (CKA) with VAc. Despite their potential, the practical use of these degradable polymers remains limited. Therefore, our study aimed to develop a sustainable technology encompassing the synthesis and application of poly(VAc-co-MDO), and environmental biodegradability of poly(vinyl alcohol (VA)). To achieve this, we synthesized a series of degradable copolymers, namely poly(VAc-co-MDO), via free radical ring-opening polymerization (rROP) of 2-methylene-1,3-dioxepane (MDO) with VAc. The number of degradable ester units in the polymer backbone was systematically controlled by varying the initial monomer feed compositions, resulting in a range of 8–85 mol%. To compare their properties, we also synthesized homopolymers, namely poly(VAc) and poly(MDO). Subsequently, we formulated the homo and copolymers into microparticles using the co-solvent evaporation method, which yielded spherical particles with a particle size distribution ranging from 5 to 10 µm. Furthermore, we demonstrated the applicability of these degradable copolymers, exemplified by a poly[VAc(0.92)-co-MDO(0.08)] with 8 mol% MDO in the polymer backbone, in an encapsulation modeling study using curcumin as the active molecule. Successful encapsulation of curcumin into degradable polymer particles was confirmed and quantified via HPLC analysis. The degradability of the copolymers was evaluated through accelerated alkali hydrolysis, resulting in the formation of oligomeric degradation products. Additionally, we investigated the environmental biodegradability of poly(VA-co-MDO) as a proof of concept, revealing a biodegradability of 89% within 28 days for this polymer consisting of 88 mol% poly(VA) and 12 mol% poly(MDO) in the backbone. Preparing stable formulation for applications and performing biodegradability tests for the copolymers or microparticles derived from random poly(VAc-co-MDO) was challenging due to the insolubility of the polymer or instability in the form of sedimentation of the microparticles in the inoculum. Hence, in order to achieve stable formulation, we synthesized random poly(VA-co-MDO) through the selective cleavage of chloroacetyl group (ClAc) from its precursor, poly(VClAc-co-MDO). This method was preferred because obtaining poly(VA-co-MDO) directly from poly(VAc-co-MDO) was hindered by significant ester backbone cleavage, even under mild conditions. Our research assumes significance in light of recent restrictions imposed by various chemical agencies on the use of non-degradable polymers and microparticles in formulations.

Synthesis of polymer-vesicle latex particles through an ATRP-based approach

The synthesis of polymer-vesicle latex particles by using extruded vesicles of dimethyldioctadecyl ammonium bromide (DODAB) via an atom transfer radical polymerization–based approach is reported. Cryo-TEM characterization revealed the growth of polymer from one side of the vesicle, and the final morphology of the resulting particles was affected by monomer feed composition. Protrusions or nanocapsules were synthesized when MMA:BA:EGDMA or MMA were used, respectively. Furthermore, it was found that the co-oligomer composition and chain length affect the resulting morphologies of the particles.Graphical abstract

Synthesis and characterization of poly(trimetylene carbonate-co-ε-caprolactone) prepared by ring-opening polymerization using samarium(III) acetate as initiator

Random copolymers of trimethylene carbonate and ε-caprolactone were synthesized by ring-opening polymerization varying the feed ratio. For this, samarium (III) acetate was used as an initiator at 110 °C for 24 h. The structure of copolymers was characterized by nuclear magnetic resonance spectroscopy and size exclusion chromatography, and differential scanning calorimetry was used to determine thermal properties. The effect of monomer feed composition on the copolymerization was analyzed, showing that the composition of the copolymers (F CL/F TMC), agreed with the feed dose. Conversion studies were made, and reactivity ratios of both monomers (rn ) were obtained, their values were r CL = 0.849 for caprolactone (CL) and r TMC = 1.261 for trimethylene carbonate (TMC), which indicated that TMC was more active than CL.

Tailoring nano-copolymer/CNTs composite and its application in drug delivery

This work aimed to overcome the main drawbacks of some essential anticancer drugs as 5-Fluorouracil (5-FU) by controlled loading with novel drug carriers. By a differential microemulsion technique, nanosized particles derived from a copolymer of poly(methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA)) with different monomer ratios have been synthesized and used as a drug carrier. Poly(MMA-co-HEMA)/MWCNT nanocomposite was also synthesized using an in-situ microemulsion polymerization technique and used as a 5-FU carrier. Different techniques have characterized these ground-breaking drug delivery systems such as FT-IR, XRD, TEM, TGA, zeta potential, and a particle size analyzer. The effects of monomer feed composition, 5-FU content, and MWCNTs content on morphological and structural properties, in-vitro 5-FU release, and entrapment efficiency (EE%) have been studied. It was noted that the inclusion of MWCNTs in the 5-FU-loaded polymer increases the thermal stability and raises the entrapment efficiency (EE%) to hit 99% at CNTs:5-FU ratio of 2:1. The anticancer drug release from the co-polymeric nanospheres depends on the HEMA ratio, 5-FU/copolymer ratio, CNT/5-FU ratio, and the pH of the medium. The optimized nanocomposite demonstrated higher anti-tumor activity against the cell lines CaCo-2, MCF-7, and HepG-2 and higher cytotoxicity against HepG-2 relative to CaCo-2 and MCF-7.

Polymerization-induced phase separation in gradient copolymers

Gradient copolymers of styrene and N-vinylpyrrolidone, obtained in bulk using the reversible deactivation radical polymerization process under the action of TEMPO nitroxide, can form microphase-like separated structures directly in the reaction medium without any additional treatment or solvent. The morphology of the resulting product is highly dependent on the monomer feed composition.

Thermomechanical analysis and pH-triggered elastic response of charge-balanced sulfonated poly(tertiary amine-methacrylate)-based terpolymer cryogels

pH-responsive terpolymer poly(hydroxyethyl methacrylate-2-acrylamido-2-methyl-propanosulfonic acid-diethylaminoethyl methacrylate) cryogels and hydrogels (named as CGs-PHA/Dm and HGs-PHA/Dm) were synthesized in ethanol-water mixture using different monomer feed compositions. By the combination of three monomers, an interesting system was designed with tunable pH/temperature responsiveness and elasticity. ATR-FTIR spectrums obtained after swelling swelling in pH buffer solution of 2.1 indicated –R2NH+ stretching of DEAEMA moities in terpolymer matrices. By incorporation of DEAEMA units with ionizable amino groups, terpolymer CGs-PHA/Dm and HGs-PHA/Dm gels exhibited pH-responsive swelling behavior. Inclusion of DEAEMA dramatically altered pH-responsiveness of terpolymers in simulated intestinal fluid at pH 6.6. Dependence of interaction parameter χon terpolymer volume fraction in gel ν2by a linear function and its enthalpic/entropic components with swelling pH were determined. At pH < 6.6, dependence of χ parameter on the swelling was evaluated as χ=1.097-2.965ν2, while at basic pH region, pH > 6.6, χ=0.576+0.459ν2. Both pH of swelling medium and the amount of DEAEMA in terpolymer composition affected the compression moduli of terpolymer gels. Flory-Rehner theory extended to correlate the compressive modulus with swelling pH and the dependence of the effective crosslink density νeon mol% DEAEMA was expressed in both acidic and basic conditions. pH-triggered swelling/shrinking of terpolymer gels were studied as reversible cycles in buffer solutions of pH 2.1 and 9.8. DEAEMA-rich terpolymer gels showed overshooting phenomena due to dynamic conformational changes of diethylaminoethyl units. Terpolymer cryogels exhibited much faster swelling kinetics than that of terpolymer hydrogels in simulated gastric fluid at pH 2.1. The values of diffusion coefficient seemed to be strongly dependent of terpolymer composition.

Dynamic Monte Carlo Simulation for Chain‐Shuttling Polymerization of Olefin Block Copolymers in Continuous Stirred‐Tank Reactor

AbstractA dynamic Monte Carlo model coupling with residence time distribution is developed to simulate chain microstructures of olefin block copolymers (OBCs) produced with the chain‐shuttling polymerization in a continuous stirred‐tank reactor (CSTR). The simulated results provide information on how polymer chain microstructures (i.e., average molecular weight, average comonomer content, and microstructural distributions) evolve in a CSTR system and show a good agreement with previously reported theoretical and experimental results. The model is also used to investigate effect of reaction conditions (i.e., catalyst feed compositions, monomer feed compositions, and mean residence time) on time evolution of OBC chain microstructures.

Microwrinkled pH-sensitive hydrogel films and their role on the cell adhesion/proliferation.

In this work, hydrogels based on HEMA and DMAEMA (pH-sensitive monomer) were used to form biocompatible films which present microwrinkled patterns in their surface, with the focus of exploring the role of chemical composition on cell adhesion and proliferation. Three different pH (5.4, 7.4, and 8.3) were employed to prepare these hydrogels. The pre-polymerized hydrogel mixtures were deposited via spin coating, then exposed to vacuum for deswelling the films and finally, to UV-light to spontaneously generate the wrinkled pattern. By following this procedure, is possible to form a thin rigid layer on the top of the soft and incompletely polymerized hydrogel film which generates, in turn, a wrinkled pattern due to strain mismatch in the interface. FE-SEM and AFM micrographs allowed us to characterize the wrinkled pattern dimensions. The results evidenced that chemical composition is directly related to the surface pattern morphologies obtained, not so in the case of pH variation, which does not generate relevant changes in the pattern morphology. Interestingly, these pH variations resulted in significant alterations on the interface-cell interactions. More precisely, a premyoblastic cell monolayer was cultured over the wrinkled pattern, showing an optimal cell proliferation at neutral pH. Also, the variation of DMAEMA amount on the monomer feed composition employed for the preparation of the wrinkle surfaces revealed that a certain amount is required to favor cell attachment and growth.

Micro-wrinkled hydrogel patterned surfaces using pH-sensitive monomers

Herein, we report the fabrication of wrinkled hydrogel films with tunable pH sensitivity by using tertiary amine methacrylate-based monomers. On the one hand, hydrogels composed of 2-hydroxyethyl methacrylate (HEMA), N,N-diethylaminoethyl methacrylate (DEAEMA), and poly(ethylene glycol) diacrylate (PEGDA575) were synthesized using different monomer feed. Their pH responsiveness was tested via contact angle measurements using different buffers (pH 5.4, 7.4 and 8.3) as aqueous media. On the other hand, the same buffers were used as solvent during synthesis instead of water. Later, hydrogel films were deposited by spin coating onto methacryloyl-functionalized substrates, in order to form a covalent anchoring to the surface.The monomer conversion ratio was inspected by 1H NMR analysis, demonstrating a partial conversion in the first thermo-polymerization step and a complete reaction upon at the end. AFM and FE-SEM micrographs provide topographical information about the surfaces, like wrinkled pattern width, height, and wrinkles preferential direction. Force spectroscopy measurements depict some clues about the local micromechanical properties of the films, evidencing a clear influence of the monomer feed composition on the final characteristics of the hydrogel patterns. Contact angle measurements evidence an important pH responsiveness which is increased by adding a larger amount of DEAEMA to the feed.

In Situ Semibatch Emulsion Polymerization of 2‐Ethyl Hexyl Acrylate/n‐Butyl Acrylate/Methyl Methacrylate/Cellulose Nanocrystal Nanocomposites for Adhesive Applications

AbstractCellulose nanocrystals (CNCs) are safe, “green,” hydrophilic nanoparticles. CNCs are added in situ during a semibatch 2‐ethyl hexyl acrylate (EHA)/n‐butyl acrylate (BA)/methyl methacrylate (MMA) emulsion polymerization. As EHA is a more hydrophobic monomer, manipulation of the monomer feed composition allows for the evaluation of the effect of hydrophobicity on CNC distribution in the nanocomposite and ultimately on adhesive properties. The adhesive properties (loop tack, peel strength, and shear strength) of three different EHA/BA/MMA latex formulations are shown to simultaneously improve with increasing CNC loading. However, the hydrophobicity of the EHA leads to a nonuniform distribution of CNCs in the latex films. Comparison of the in situ polymerized nanocomposites to their blended counterparts is also made.

Characterization, In Vitro Evaluation and Stability Studies of Indomethacin-Loaded Polyzwitterionic Copolymer Nanoparticles

The aim of the study was to investigate the influence of the nature and composition of the monomer feed, added to the reaction system indomethacin/vinyl acetate/3-dimethyl (methacryloyloxyethyl) aminopropyl sulfonate (IMC/VAc/DMAPS) and the characteristics of the obtained polymer latexes on indomethacin In-situ loading, its kinetic release properties, and drug stability. Indomethacin loaded nanoparticles were obtained by an emulsifier-free emulsion radical copolymerization of the monomers, in presence of the drug. Transmission electron microscopy, Attenuated Total Reflection Fourier Transform Infrared spectroscopic analyses, Particle size distribution and zeta potential analysis were carried out to characterize the In-situ loaded nanocarriers. High-performance liquid chromatography and UV/VIS spectroscopic analyses were applied to determine the drug loading, In vitro release properties and stability studies of the drug used. High yield of 90 to 96% was obtained for the tested In-situ loaded nanocarriers. They possess a spherical shape with diameter ranging from 100 to 900 nm and zeta potential from -3.25 mV to -20.3 mV. Mono-modal and bi-modal particle size distribution was observed depending on monomer feed, added to the reaction system. It also influenced the drug loading and its release characteristics. Indomethacin was released from the investigated patterns following first order release. The nature and composition of the monomer feed, added to the reaction system IMC/VAc/DMAPS are an effective factors for the control of the indomethacin loading and also affect the rate and extent of drug-releasing but do not influence the kinetic model and drug transport mechanism. Stability studies indicated the stabilizing role of the polymer carrier on the In-situ included indomethacin.

Controlled synthesis of amphiphilic block copolymers based on poly(isobutylene) macromonomers

ABSTRACTThe synthesis of a monoacrylate functionalized poly(isobutylene) (PIB) macromonomer (PIBA) has been achieved by a two‐step reaction starting from a commercially available PIB. Firstly, terminal olefins (vinylidene and trisubstituted olefin) of PIB were transformed to a phenolic residue by Friedel‐Crafts alkylation followed by subsequent esterification of the phenol with acryloyl chloride, catalyzed by triethylamine. PIBA structure was confirmed by 1H‐NMR, 13C‐NMR and GPC before utilizing in the RAFT copolymerization with N,N‐dimethylacrylamide (DMA) to obtain statistical copolymers (P[(DMA‐co‐(PIBA)]). Monomer conversions were consistently higher than 85% for both DMA and PIBA as monomer feed composition was varied. Chain extension of poly(N,N‐dimethylacrylamide) with PIBA to synthesize block copolymers (P[(DMA‐b‐(PIBA)]) was also achieved with near quantitative monomer conversions (&gt;97%). Block formation efficiency was not quantitative but purification of block copolymers was possible by selective precipitation. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 634–643

Preparation, Characterization, and Microstructure of Poly(ε‐caprolactone–co‐2,2‐dimethyltrimethylene carbonate) Using Metal‐free Organocatalysts

We investigated the random copolymerization of ε‐caprolactone and 2,2‐dimethyltrimethylene carbonate [poly(CL‐co‐DTC)] promoted by various imidazolium‐based carbenes, including 1‐isopropyl‐3‐p‐methoxyphenylimidazol‐2‐ylidene [Catalyst (1)], 1‐isopropy‐3‐p‐methylphenylimidazol‐2‐ylidene [Catalyst (2)], and 1‐methyl‐3‐p‐methoxyphenyl‐imidazol‐2‐ylidene [Catalyst (3)], all of which are new types of unsymmetrical N‐heterocyclic carbene catalysts. The reaction was carried out in the presence of benzyl alcohol (BnOH) as an initiator in tetrahydrofuran. By varying the experimental conditions and the monomer feed composition, poly(CL‐co‐DTC) with high yield and molecular weight was prepared using the binary system Catalyst (1)/BnOH as catalyst/initiator. 1H NMR and differential scanning calorimetry (DSC) characterizations verified random structures of the polymer. GPC characterization further showed high molecular weights and narrow molecular weight distribution of the final product.

Novel Copolymers of Styrene. 10. Halo Ring-Substituted 2-Cyano-3-phenyl-2-propenamides

Novel electrophilic trisubstituted ethylene monomers, halo ring-substituted 2-cyano-3-phenyl-2-propenamides, RPhCH ˭ C(CN)CONH2, where R is 2-bromo, 3-bromo, 2-fluoro, 3-fluoro, 2-iodo, 3-iodo, and 4-iodo were prepared and copolymerized with styrene. The monomers were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide, and characterized by CHN elemental analysis, IR, 1H- and 13C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H- and 13C-NMR, GPC, DSC, and TGA. High Tg of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (7-19 wt%), which then decomposed in the 500–800°C range.

Novel Copolymers of Styrene. 11. Ring-Substituted 2-Cyano-3-phenyl-2-propenamides

Novel electrophilic trisubstituted ethylene monomers, halo ring-disubstituted 2-cyano-3-phenyl-2-propenamides, RPhCH = C(CN)CONH2, where R is 2,3-difluoro, 2,4-difluoro, 2,5-difluoro, 2,6-difluoro, 3,4-difluoro, 3,5-difluoro, 2-chloro-4-fluoro, 3-chloro-2-fluoro, 3-chloro-4-fluoro were prepared and copolymerized with styrene. The monomers were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide, and characterized by CHN elemental analysis, IR, 1H- and 13C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H- and 13C-NMR, GPC, DSC, and TGA. High Tg of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (10–14 wt%), which then decomposed in the 500–800°C range.

Novel Copolymers of Styrene. 8. Ring-Trisubstituted 2-Cyano-3-phenyl-2-propenamides

Novel trisubstituted ethylenes, ring-trisubstituted 2-cyano-3-phenyl-2-propenamides, RC6H2CH˭C(CN)CONH2 (where R is 2,4,6-trimethyl, 2,3-dimethyl-4-methoxy, 2,3,4-trimethoxy, 2,4,5-trimethoxy, 2,4,6-trimethoxy, and 3,4,5-trimethoxy) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-trisubstituted benzaldehydes and cyanoacetamide and characterized by CHN elemental analysis, IR, 1H- and 13C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution in the presence of a radical initiation (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H- and 13C-NMR, GPC, DSC, and TGA. Thus, the order of relative reactivity (1/r1) and the tendency toward alternation of monomer units in the copolymer for the monomers is 2,4,6-(CH3)3 (0.71) > 2,3-(CH3)2-4-CH3O (0.52) > 2,3,4-(CH3O)3 (0.34) > 2,4,5-(CH3O)3 (0.30) > 3,4,5-(CH3O)3 (0.15) > 2,4,6-(CH3O)3 (0.12). High Tg of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (2.9–9.9 wt%), which then decomposed in the 500–800°C range.

Novel Copolymers of Styrene. 9. Methyl and Methoxy Ring-Substituted 2-Cyano-3-phenyl 2-propenamides

Novel electrophilic trisubstituted ethylene monomers, methyl and methoxy ring- substituted 2-cyano-3-phenyl-2-propenamides, RPhCH=C(CN)CONH2, where R is 2,3-dimethyl, 2,4-dimethyl, 2,5-dimethyl, 2-(3-methoxyphenoxy), 2-(4-methoxyphenoxy), 3-(4-methoxyphenoxy), 4-(4-methylphenoxy), 2,3-methylenedioxy were prepared and copolymerized with styrene. The monomers were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide, and characterized by CHN elemental analysis, IR, 1H- and 13C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution copolymerization in the presence of a radical initiator, ABCN at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H- and 13C-NMR, GPC, DSC, and TGA. High Tg of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (5.8–33.8 wt%), which then decomposed in the 500–800°C range.

Novel Copolymers of Styrene. 7. Chlorine Ring-Substituted 2-Cyano-3-phenyl-2-propenamides

Novel trisubstituted ethylenes, chlorine ring-substituted 2-cyano-3-phenyl-2-propenamides, RC6H3CH˭C(CN)CONH2 (where R is 2,3-dichloro, 2,4-dichloro, 2,6-dichloro, 3,4-dichloro, 2-chloro-5-nitro, 4-chloro-3-nitro, 5-chloro-2-nitro) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide and characterized by CHN elemental analysis, IR, 1H- and 13C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution in the presence of a radical initiation (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H- and 13C-NMR, GPC, DSC, and TGA. Thus, the order of relative reactivity (1/r1) and the tendency toward alternation of monomer units in the copolymer for the monomers is 2-Cl-5-NO2 (3.09) > 5-Cl-2-NO2 (1.88) > 4-Cl-3-NO2 (0.97) > 2,6-Cl2 (0.93) > 3,4-Cl2 (0.31) > 2,4-Cl2 (0.30) > 2,3-Cl2 (0.22). High Tg of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (3.5–5.0 wt%), which then decomposed in the 500–800°C range.