Synthesis,characterization, and thermal degradation of novel poly(2‐(5‐bromo benzofuran‐2‐yl)‐2‐oxoethyl methacrylate)

A novel methacrylate monomer containing benzofuran side group, 2‐(5‐bromo benzofuran‐2‐yl)‐2‐oxoethyl methacrylate (BOEMA), was synthesized from esterification reaction of 2‐bromo‐1‐(5‐bromo benzofuran‐2‐yl) ethanone with sodium methacrylate at 85°C in the presence of 1,4‐dioxane solvent. After characterization with Fourier transform infrared spectrophotometer, nuclear magnetic resonance (¹H‐NMR and ¹³C‐NMR), its homopolymerization was carried out by free radical polymerization at 60°C in the presence of benzoyl peroxide initiator and 1,4‐dioxane solvent. The glass transition temperature (T_g) of the synthesized novel polymer, poly(2‐(5‐bromo benzofuran‐2‐yl)‐2‐oxoethyl methacrylate) [poly(BOEMA)], was determined to be 137°C with differential scanning calorimetry technique. Thermal degradation kinetics of poly(BOEMA) was investigated by thermogravimetric analysis method at different heating rates with 5°C/min intervals between measurements. From dynamic measurements, the analysis of each process mechanism of Coats–Redfern and Van Krevelen methods showed that the most probable model for the decomposition process of poly(BOEMA) homopolymer agrees with the random nucleation, F₁ mechanism. The apparent decomposition activation energies of poly(BOEMA) by Kissinger's and Flynn–Wall–Ozawa methods in the studied conversion range were 188.47 and 180.13 kJ/mol, respectively. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Preparation and properties of ethylene/POSS copolymer with rac‐Et(Ind)2ZrCl2 catalyst

The various monovinyl‐functional polyhedral oligomeric silsesquioxane (POSS) monomers had been copolymerized with ethylene (E) using rac‐Et(Ind)₂ZrCl₂ and a modified methylaluminoxane (MMAO) cocatalyst. The unreacted POSS monomer could be removed completely by washing the copolymerization product with n‐hexane. And the copolymers were characterized with ¹H NMR, TEM, DSC, TGA, and GPC to know the composition, thermal properties, molecular weight and its distribution, respectively. According to ¹H NMR data, the monomer reactivity ratios of various POSS monomers were calculated by the Fineman‐Ross and Kelen‐Tudos methods. Thermogravimetric analysis of E/POSS copolymers exhibited an improved thermal stability with a higher degradation temperature and char yields, demonstrating that the inclusion of inorganic POSS nanoparticles made the organic polymer matrix more thermally robust. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of poly[(1‐vinyl‐1,2,4‐triazole)‐co‐(monomer with carboxylic acid group(s))] and determination of monomer reactivity ratios: I. Acrylic acid

Copolymers of 1‐vinyl‐1,2,4‐triazole (VTAz) and acrylic acid (AA) having different mole ratios were synthesized using free radical‐initiated solution polymerization in dimethylformamide at 70 °C with α,α′‐azobisisobutyronitrile as initiator in nitrogen atmosphere. The compositions of the synthesized copolymers for a wide range of monomer feeds were determined using Fourier transform infrared (FTIR) spectroscopy through recorded absorption bands for VTAz (1510 cm^?1, C?N (triazole ring) stretching mode) and AA (1710 cm^?1, C?O stretching mode) units. The structures of the copolymers were characterized using FTIR and ¹H NMR spectroscopy. The copolymer compositions were also determined from ¹H NMR analysis following proton signals of carboxyl group at 11.8–12.5 ppm of AA and of triazole ring at 7.5–8.1 ppm of VTAz. Monomer reactivity ratios for the VTAz‐AA pair were estimated using linear methods, i.e. Fineman–Ross (FR) and Kelen–Tüdös (KT). From FTIR evaluation, monomer reactivity ratios were calculated as r₁ = 0.404 and r₂ = 1.496 using the FR method and r₁ = 0.418 and r₂ = 1.559 using the KT method. These values were found to be very close to those obtained from NMR evaluation. The two cases r₁r₂ < 1 and r₁ < r₂ indicated the random distribution of the monomers in the final copolymers and the presence of a greater amount of AA units in the copolymer than in the feed, respectively. The observed relatively high activity of complexed growing radical‐AA^? … VTAz was explained by the effect of complex formation between carbonyl groups and triazole fragments in chain growth reactions. Thermal behaviours of copolymers with various compositions were investigated using thermogravimetric and differential scanning calorimetric analyses. It was observed that thermal stabilities and glass transition temperatures of the copolymers increased resulting from complex formation between acid and triazole units. © 2012 Society of Chemical Industry     

Copolymerization of N‐aryl substituted itaconimide with methyl methacrylate: Effect of substituents on monomer reactivity ratio and thermal behavior

The article describes the synthesis and characterization of N‐(4‐methoxy‐3‐chlorophenyl) itaconimide (MCPI) and N‐(2‐methoxy‐5‐chlorophenyl) itaconimide (OMCPI) obtained by reacting itaconic anhydride with 4‐methoxy‐3‐chloroanisidine and 2‐methoxy‐5‐chloroanisidine, respectively. Structural and thermal characterization of MCPI and OMCPI monomers was done by using ¹H NMR, FTIR, and differential scanning calorimetry (DSC). Copolymerization of MCPI or OMCPI with methyl methacrylate (MMA) in solution was carried out at 60°C using AIBN as an initiator and THF as solvent. Feed compositions having varying mole fractions of MCPI and OMCPI ranging from 0.1 to 0.5 were taken to prepare copolymers. Copolymerizations were terminated at low percentage conversion. Structural characterization of copolymers was done by FTIR, ¹H NMR, and elemental analysis and percent nitrogen content was used to calculate the copolymer composition. The monomer reactivity ratios for MMA–MCPI copolymers were found to be r₁ (MMA) = 0.32 ± 0.03 and r₂ (MCPI) = 1.54 ± 0.05 and that for MMA–OMCPI copolymers were r₁ (MMA) = 0.15 ± 0.02 and r₂ (OMCPI) = 1.23 ± 0.18. The intrinsic viscosity [η] of the copolymers decreased with increasing mole fraction of MCPI/or OMCPI. The glass transition temperature as determined from DSC scans was found to increase with increasing amounts of OMPCI in copolymers. A significant improvement in the char yield as determined by thermogravimetry was observed upon copolymerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2391–2398, 2006     

Effect of partitioning of monomer on the reactivities of monomers in microemulsion

Copolymerization of styrene and 2‐hydroxyethyl methacrylate (2‐HEMA) was carried out in a microemulsion medium. The composition of the copolymers was estimated using proton ¹H‐NMR. The reactivity ratios of styrene and 2‐HEMA in ternary microemulsions were observed and were considerable different from those reported for solution and bulk polymerization. In monomer pairs with a considerable difference in polarity, partitioning of a monomer between the aqueous phase and the microemulsion droplets develops a concentration gradient, which can be calculated from the distribution coefficient of the monomer between the two phases. This approach has led to more reliable reactivity ratios for the monomers. The study of styrene–2‐HEMA copolymerization in a sodium dodecylsulfate‐based microemulsion resulted in r_S = 3.79 and r_H = 0.17 as apparent reactivity ratios and r_S = 0.57 and r_H = 23.24 as true reactivity ratios for styrene and 2‐HEMA, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1832–1837, 2002; DOI 10.1002/app.10401     

4‐Acetamidophenyl acrylate copolymers with acrylonitrile and N‐vinyl‐2‐pyrrolidone: Synthesis,characterization, and reactivity ratios

4‐Acetamidophenyl acrylate (APA) was synthesized and characterized by IR, ¹H and ¹³C NMR spectroscopies. Homo‐ and copolymers of APA with acrylonitrile (AN) and N‐vinyl‐2‐pyrrolidone (NVP) were prepared by a free radical polymerization. All the copolymer compositions have been determined by ¹H NMR technique, and the reactivity ratios of the monomer pairs have been evaluated using the linearization methods Fineman–Ross, Kelen–Tudos, and extended Kelen–Tudos. Nonlinear error‐in‐variable model (EVM) method was used to compare the reactivity ratios. The reactivity ratios for copoly(APA–AN) system were APA(r₁) = 0.70 and AN(r₂) = 0.333, and for copoly(APA–NVP) system the values were APA(r₁) = 4.99 and NVP(r₂) = 0.019. Thermal stability and molecular weights of the copolymers are reported. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1919–1927, 2006     

Synthesis and characterization of copolymers of bromoacrylated methyl oleate

In this study, methyl oleate was bromoacrylated in the presence of N‐bromosuccinimide and acrylic acid in one step. Homopolymers and copolymers of bromoacrylated methyl oleate (BAMO) were synthesized by free radical bulk polymerization and photopolymerization techniques. Azobisisobutyronitrile (AIBN) and 2,2‐dimethoxy‐2‐phenyl‐acetophenone were used as initiators. The new monomer BAMO was characterized by FTIR, GC‐MS, ¹H, and ¹³C‐NMR spectroscopy. Styrene (STY), methylmethacrylate (MMA), and vinyl acetate (VA) were used for copolymerization. The polymers synthesized were characterized by FTIR, ¹H‐NMR, ¹³C‐NMR, and differential scanning calorimetry (DSC). Molecular weight and polydispersities of the copolymers were determined by GPC analysis. Ten different feed ratios of the monomers STY and BAMO were used for the calculation of reactivity ratios. The reactivity ratios were determined by the Fineman–Ross and Kelen–Tudos methods using ¹H‐NMR spectroscopic data. The reactivity ratios were found to be r_sty = 0.891 (Fineman–Ross method), 0.859 (Kelen–Tudos method); r_bamo = 0.671 (Fineman–Ross method), 0.524 (Kelen–Tudos method). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2475–2488, 2004     

Copolymers of poly(n-alkyl acrylates): synthesis, characterization, and monomer reactivity ratios

Poly(n-alkyl acrylate) copolymer reactivity ratios were determined for n-alkyl acrylate monomers of various side-chain lengths n ranging from 6 to 22. Two sets of copolymers were synthesized to less than <10% conversion to evaluate the reactivity ratios. The first set included P(A10-co-A14), P(A10-co-A18), and P(A14-co-A18); while the second set consisted of P(A6-co-A12), P(A6-co-A22) and P(A12-co-A22). Copolymers were formed from monomer mixtures at 25 mol% intervals ranging from 0 through 100 mol%. ¹³C NMR was performed on the homo polymers and the low conversion copolymers to determine the reactivity ratios of the monomers in each copolymer system. It was determined that the reactivity ratios for all monomers examined here were approximately equal to one. Physical properties of the copolymers, including melting point, heat of fusion, and permeation as a function of temperature, of the low conversion polymers were compared to copolymers formed at 100% conversion to demonstrate that these properties are independent of conversion because no composition drift occurs during polymerization.     

Synthesis and characterization of perfluorinated acrylate–methyl methacrylate copolymers

A novel perfluorinated acrylic monomer 3,5‐bis(perfluorobenzyloxy)benzyl acrylate (FM) with perfluorinated aromatic units was synthesized with 3,5‐bis(perfluorobenzyl)oxybenzyl alcohol, acryloyl chloride, and triethylamine. Copolymers of FM monomer with methyl methacrylate (MMA) were prepared via free‐radical polymerization at 80°C in toluene with 2,2′‐azobisisobutyronitrile as the initiator. The obtained copolymers were characterized by ¹H‐NMR and gel permeation chromatography. The monomer reactivity ratios for the monomer pair were calculated with the extended Kelen–Tüdos method. The reactivity ratios were found to be r₁ = 0.38 for FM, r₂ = 1.11 for MMA, and r₁r₂ < 1 for the pair FM–MMA. This shows that the system proceeded as random copolymerization. The thermal behavior of the copolymers was investigated by thermogravimetric analysis and differential scanning calorimetry (DSC). The copolymers had only one glass‐transition temperature, which changed from 46 to 78°C depending on the copolymer composition. Melting endotherms were not observed in the DSC traces; this indicated that all of the copolymers were completely amorphous. Copolymer films were prepared by spin coating, and contact angle measurements of water and ethylene glycol on the films indicated a high degree of hydrophobicity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Radical polymerization and copolymerization behavior of 1-cyanoethanoyl-4-acryloylthiosemicarbzide

1-Cyanoethanoyl-4-acryloylthiosemicarbazide (CEATS) was synthesized for the first time as a new chelating monomer. Its structure was confirmed by both elemental and spectral analyses. Radical polymerization and copolymerization of CEATS was been carried out in dimethylformamide (DMF) in the presence of azobisisobutyronitrile (AIBN) as an initiator. Kinetic studies for the polymerization behavior of CEATS were performed. The complex formation of the CEATS monomer and polymer (PCEATS) with Cu II cation was investigated and its stability constant determined. The rate of copolymerization of CEATS with some conventional monomers, namely vinyl acetate, methyl methacrylate and acrylonitrile, was measured as a function of the mole fraction of the monomers. The reactivity ratios (r₁, r₂) for the various copolymer systems investigated together with the Q and e values of the CEATS monomer were determined. Moreover, the thermal gravimetric analysis of the prepared polymers and their copolymers with acrylonitrile were also studied.     

Synthesis,characterization, reactivity ratios by nuclear magnetic resonance spectroscopy,and application of (2,5‐Dichlorophenyl acrylate‐co‐glycidyl methacrylate) polymers as adhesives for the leather industry

2,5‐ Dichlorophenyl acrylate (DPA)‐co‐glycidyl methacrylate (GMA) polymers having five different compositions were synthesized in 1,4‐dioxane using benzoyl peroxide as a free‐radical initiator at 70 ± 0.5°C. Using ¹H‐NMR spectroscopy, the composition of the two monomers in the copolymers was calculated by comparing the integral values of the aromatic and aliphatic proton peaks. The reactivity ratios were calculated by Fineman–Ross (r₁ = 0.31 and r₂ = 1.08), Kelen–Tudos (r₁ = 0.40 and r₂ = 1.15), and extended Kelen–Tudos (r₁ = 0.39 and r₂ = 1.16) methods. The nonlinear error‐in‐variables model was used to compare the reactivity ratios. The copolymers were characterized by ¹H and proton decoupled ¹³C‐NMR spectroscopes. Gel permeation chromatography was performed for estimating the M_w and M_n and M_w/M_n of the poly(DPA) and copolymers (DPA‐co‐GMA: 09 : 91 and 50 : 50). Thermal stability of the homo‐ and copolymers was estimated using TGA [poly(DPA) > DPA‐co‐GMA (50 : 50) > DPA‐co‐GMA (09:91)], while DSC was utilized for determining the glass transition temperature. T_g increased with increased DPA content in the copolymer. The 50 : 50 mol % copolymer was chosen for curing with diethanolamine in chloroform. The cured resins were tested for the adhesive properties on leather at different temperatures (50, 90, 100, and 110°C). The resin cured at 50 °C exhibited a maximum peel strength of 1.6 N/mm, revealing a good adhesive behavior. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1167–1174, 2006     

Synthesis and Characterization of Copolymers containing N,N-dimethylacrylamide and 2-vinyl-4,4’-dimethylazlactone

Summary We report the synthesis, characterization, and determination of monomer reactivity ratios for the solution copolymerization of N,N-dimethylacrylamide (DMA) and 2-vinyl-4,4’-dimethylazlactone (VDMA). The polymerization kinetics were monitored by gas chromatography (GC), structure analysis of the resulting copolymers was determined using ¹H-NMR analysis, and copolymer molecular weights were determined using gel-permeation chromatography (GPC). The reactivity ratios indicate the copolymerization of DMA and VDMA may result in greater mole fraction of VDMA in the copolymer compared to monomer feed compositions, especially when the DMA mole fraction is greater than the VDMA mole fraction. However, the data also indicates an azeotropic copolymerization at a mole fraction of VDMA of 0.78.     

Reactivity ratios and copolymer properties of 2‐(diisopropylamino)ethyl methacrylate with methyl methacrylate and styrene

Free radical copolymerization kinetics of 2‐(diisopropylamino)ethyl methacrylate (DPA) with styrene (ST) or methyl methacrylate (MMA) was investigated and the corresponding copolymers obtained were characterized. Polymerization was performed using tert‐butylperoxy‐2‐ethylhexanoate (0.01 mol dm^?3) as initiator, isothermally (70 °C) to low conversions (<10 wt%) in a wide range of copolymer compositions (10 mol% steps). The reactivity ratios of the monomers were calculated using linear Kelen–Tüd?s (KT) and nonlinear Tidwell–Mortimer (TM) methods. The reactivity ratios for MMA/DPA were found to be r₁ = 0.99 and r₂ = 1.00 (KT), r₁ = 0.99 and r₂ = 1.03 (TM); for the ST/DPA system r₁ = 2.74, r₂ = 0.54 (KT) and r₁ = 2.48, r₂ = 0.49 (TM). It can be concluded that copolymerization of MMA with DPA is ideal while copolymerization of ST with DPA has a small but noticeable tendency for block copolymer building. The probabilities for formations of dyad and triad monomer sequences dependent on monomer compositions were calculated from the obtained reactivity ratios. The molar mass distribution, thermal stability and glass transition temperatures of synthesized copolymers were determined. Hydrophobicity of copolymers depending on the composition was determined using contact angle measurements, decreasing from hydrophobic polystyrene and poly(methyl methacrylate) to hydrophilic DPA. Copolymerization reactivity ratios are crucial for the control of copolymer structural properties and conversion heterogeneity that greatly influence the applications of copolymers as rheology modifiers of lubricating oils or in drug delivery systems. © 2015 Society of Chemical Industry     

Synthesis,characterization, and reactivity ratios of copolymers derived from 4‐nitrophenyl acrylate and n‐butyl methacrylate

Free‐radical copolymerization of 4‐nitrophenyl acrylate (NPA) with n‐butyl methacrylate (BMA) was carried out using benzoyl peroxide as an initiator. Seven different mole ratios of NPA and BMA were chosen for this study. The copolymers were characterized by IR, ¹H‐NMR, and ¹³C‐NMR spectral studies. The molecular weights of the copolymers were determined by gel permeation chromatography and the weight‐average (M _w) and the number‐average (M _n) molecular weights of these systems lie in the range of 4.3–5.3 × 10⁴ and 2.6–3.0 × 10⁴, respectively. The reactivity ratios of the monomers in the copolymer were evaluated by Fineman–Ross, Kelen–Tudos, and extended Kelen–Tudos methods. The product of r₁, r₂ lies in the range of 0.734–0.800, which suggests a random arrangement of monomers in the copolymer chain. Thermal decomposition of the polymers occurred in two stages in the temperature range of 165–505°C and the glass transition temperature (T_g) of one of the systems was 97.2°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1817–1824, 2003     

Associating behaviour of polyacrylamide modified with a new hydrophobic zwitterionic monomer

The nucleophilic ring opening of dicyanoketene ethylene acetal by tertiary amino monomers leads to an hydrophobic zwitterionic monomer [(dimethylammonioethoxy)dicyanoethenolate]propylmethacrylamide (DADPMA) characterized by a very high dipole moment. Hydrophobically modified water soluble polymers have been prepared by classical radical polymerization of acrylamide and DADPMA either in homogeneous medium (water/ethanol mixtures) or in micellar solution (water containing sodium dodecylsulphate (SDS)). The copolymers obtained have a high molecular weight (M _w = 2–5 × 10⁶ g mol^?1) and are water soluble for a content of DADPMA lower than 1% mole/mole. The properties of the copolymers in aqueous solution depend on the synthesis conditions, especially on the ratio ethanol:zwitterionic monomer. © 2001 Society of Chemical Industry     

Copolymerization of 4-cyanophenyl methacrylate with methyl methacrylate: Synthesis,characterization and determination of monomer reactivity ratios

Summary A novel methacrylic monomer, 4-cyanophenyl methacrylate (CPM) was synthesized by reacting 4-cyanophenol dissolved in methyl ethyl ketone (MEK) with methacryloyl chloride in the presence of triethylamine as a catalyst. Copolymers of CPM with methyl methacrylate(MMA) at different composition was prepared by free radical solution polymerization at 70±1 °C using benzoyl peroxide as initiator. The copolymers were characterized by FT-IR, ¹H-NMR and ¹³C-NMR spectroscopic techniques. The solubility of the polymers was tested in various polar and non polar solvents. The molecular weight and polydispersity indices of the copolymers were determined using gel permeation chromatography. The glass transition temperature of the copolymers increases with increase in mole fraction of MMA content. The thermal stability of the copolymer increases with increases in mole fraction of CPM content in the copolymer. The copolymer composition was determined by using ¹H-NMR spectroscopy. The monomer reactivity ratios estimated by the application of linearization methods such as Fineman-Ross (r₁=2.524±0.038, r₂=0.502±0.015), Kelen-Tudos (r₁=2.562±0.173, r₂=0.487±0.005) and extended Kelen-Tudos methods (r₁=2.735±0.128, r₂=0.4915±0.007).     

Synthesis and characterization of high molecular weight side chain liquid crystalline/photoactive polymers

Various liquid crystalline and photoactive azobenzene monomers were synthesized and attached to copoly(methyl methacrylate‐glycidyl methacrylate) [copoly (MMA‐GMA)] to get high molecular weight side chain liquid crystalline (LC)/photoactive copolymers. Further, spacers are generated in situ and reactive groups are obtained after the modification. All monomers and polymers were thoroughly characterized by FTIR, ¹H and ¹³C NMR, UV‐VIS spectrophotometry, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy. All side chain LC polymers showed higher thermal stability than that of copoly(MMA‐GMA). Three LC and one azo monomer exhibited characteristic nematic mesophase where as one LC monomer has shown nematic and sanded smectic‐A texture. The rate of trans‐cis isomerization of polymer was lower than that of the monomer and both monomers and polymers showed slow back isomerization. Present approach offers convenient way to synthesize high/desired molecular weight photoactive LC polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Copolymerization of 2-(4-tert-butylphenoxy)-2-oxo-ethyl Methacrylate with Methyl Methacrylate and Styrene: Synthesis, Characterization, and Monomer Reactivity Ratios

A tertierbutylphenoxy group containing methacrylate based monomer 2-(4-tert-butylphenoxy)-2-oxo-ethyl methacrylate (TBPOEMA) was synthesized by reacting 4-tertierbutylphenyl chloroacetate (TBPClAcO) with sodium methacrylate in acetonitrile. TBPClAcO was prepared by reacting tertierbutylphenol dissolved in benzene with chloroacetylchloride. The free-radical-initiated copolymerization of TBPOEMA, with methyl methacrylate (MMA) and styrene (ST) was carried out in dimethylsulphoxide (DMSO) solution at 65°C using 2,2-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The monomer TBPOEMA and copolymers were characterized by FTIR, ¹H- and ¹³C-NMR spectral studies. The copolymer composition obtained from the ¹H-NMR spectra led to the determination of reactivity ratios. The reactivity ratios of the monomers were determined by the application of Finemann–Ross and Kelen–Tüdös linear methods and the Behnken nonlinear least-squares method. The analysis of reactivity ratios revealed that MMA and ST are more reactive than TBPOEMA, and copolymers formed are statistical in nature. The molecular weights _w and _n) and polydispersity index of the polymers were determined using gel permation chromagtography. Thermogravimetric analysis of the polymers reveal that the thermal stability of the copolymers increases with an increase in the mole fraction of TBPOEMA in the copolymers. Glass transition temperatures of the copolymers were found to decrease with an increase in the mole fraction of TBPOEMA in the copolymers. The apparent thermal decomposition activation energies (E _d) were calculated by Ozawa method using the SETARAM Labsys TGA thermobalance.     

Synthesis, characterization, and reactivity ratio studies on new sulfide copolymers containing ethylbenzene units

Soluble new sulfide copolymers were synthesized readily by the polycondensation of ethylene dibromide (EDB) (or methylene dibromide (MDB)) with styrene dibromide (SDB) and sodium sulfide (Na₂S) in the presence of phase transfer catalyst. The copolymers were characterized by using Fourier transform-infrared, ¹H NMR, ¹³C NMR, gel permeation chromatography, and thermogravimetric analysis (TGA) techniques. The copolymer composition obtained from the ¹H NMR spectra led to the determination of reactivity ratios. The analysis of reactivity ratios revealed that both EDB and MDB are more reactive than SDB towards Na₂S, and copolymers formed are random in nature. Furthermore, it also gave an insight on the microstructure of the copolymers that both poly (ethylene sulfide-co-styrene sulfide) (p(ES-co-SS)), and poly(methylene sulfide-co-styrene sulfide) (p(MS-co-SS)) copolymers have more of blocky structure with increase in the concentration of ethylene sulfide (ES) or methylene sulfide (MS) units in the respective copolymers. The TGA was used to find out the thermal stability of these polymers. The XRD data indicated an increase in the amorphous content of the copolymers with an increase in the concentration of styrene sulfide (SS) units and thereby resulting in most of these copolymers being soluble in common organic solvents. The solubility and molecular weight of the polymers formed were dependent on the concentration of SDB taken in the feed.     

SEMICONTINUOUS EMULSION COPOLYMERIZATION OF BUTYL ACRYLATE-STYRENE†

Butylacrylate (BA)-Styrene (St) copolymers have been synthesized via a semicontinuous emulsion process in which the monomers feeding rate and weight ratios (BA/St) were varied. The feed consisted of only pure monomers which were added to an aqueous solution that contained the emulsifier and initiator

The experimental results show that monomer consumption is governed by the feeding rate as well as by the monomer's reactivity, The average molecular weight decreased as the feeding rate increased independent of the BA/St ratio

Measurement of the latex average particle size and particle number, as a function of the reaction time. showed a complex sequence of particle formation and agglomeration. In general, the average particle diameter increased in direct proportion to the feeding rate. This fact suggests that most probably homogeneous nucleation is preferred over monomer diffusion to the previously formed particles. Additionally, the monomer reactivity ratios (r ₁, r ₂) decreased as the monomer feeding rate was increased

The experimental copolymer compositions determined by gas chromatography and NMR-H⁺ showed that the resulting copolymers were closely homogeneous.