Preparation of heat‐resistant gradient‐index polymer optical fiber rods based on poly(N‐isopropylmaleimide‐co‐methyl methacrylate)

Using the interfacial gel polymerization method, a heat‐resistant gradient‐index polymer optical fiber (GI POF) was developed based on the copolymer of methyl methacrylate (MMA) and N‐isopropylmaleimide (IPMI) as the matrix material and bromobenzene (BB) as dopant. The gradient distribution of IPMI in the GI POF rod was determined by element analysis. IPMI had great advantage in improving glass transition temperature (T_g) and forming a gradient‐index profile. There was a significant enhancement in the heat‐resistant property in comparison with a conventional GI POF rod. The combination of high thermal stability and easy fabrication makes the novel BB–IPMI–MMA system very suitable for heat‐resistant GI POF. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 280–283, 2003     

Synthesis and characterization of poly[4‐(2‐thiazolylazo)phenyl methacrylate]‐co‐poly(methyl methacrylate)

A new methacrylic monomer, 4‐(2‐thiazolylazo)phenylmethacrylate (TPMA) was synthesized. Copolymerization of the monomer with methyl methacrylate (MMA) was carried out by free radical polymerization in THF solution at 70 ± 0.5°C, using azobisisobutyronitrile (AIBN) as an initiator. The monomer TPMA and the copolymer poly(TPMA‐co‐MMA) were characterized by Fourier transform infrared (FTIR), ¹H nuclear magnetic resonance (NMR), and elemental analysis methods. The polydispersity index of the copolymer was determined using gel permeation chromatography (GPC). Thermogravimetric analysis (TGA) of the copolymer performed in nitrogen revealed that the copolymer was stable to 270°C. The glass transition temperature (T_g) of the copolymer was higher than that of PMMA. The copolymer with a pendent aromatic heterocyclic group can be dissolved in common organic solvents and shows a good film‐forming ability. Both the monomer TPMA and the copolymer poly (TPMA‐co‐MMA) have bright colors: orange and yellow, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2152–2157, 2007     

Methyl methacrylate based copolymers and terpolymers: Preparation,identification, and plasticizing capability for a poly(methyl methacrylate) used in aviation

In this study, we first synthesized transparent poly(methyl methacrylate–maleic anhydride) [P(MMA–MAH)] and poly(methyl methacrylate–maleic anhydride–N‐2‐methyl‐4‐nitrophenyl maleimide) [P(MMA–MAH–MI)] via free‐radical polymerization at different monomer ratios. The synthesized polymers were characterized by titration, viscometric, spectroscopy, and thermal analyses. Higher contents of maleic anhydride (MAH) resulted in increases in the viscosity, glass‐transition temperature (T_g), and transparency. The synthesized polymers were then blended with a commercial‐grade poly(methyl methacrylate) (PMMA) used in aviation in the presence of CHCl₃. According to the free volume theory, the incorporation of 5 wt % P(MMA–MAH)s or P(MMA–MAH–MI)s into the commercial PMMA resulted in a plasticizing impact on this thermoplastic, which was confirmed by the decrease in the T_g values of the blends with almost the same transparency as the initial PMMA. In fact, the higher the content of MAH was, the lower the T_g of the blends was. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46603.     

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     

Synthesis and Characterization of Methylmethacrylate-alt-N-vinyl-2-pyrrolidone Initiated by Phosphorus Containing 1,2 Dipolar Compound

Copolymerization of methylmethacrylate (MMA) with 1-vinyl-2-pyrrolidone (N-VP), initiated by p-nitrobenzyl triphenyl phosphonium ylide in dioxane at 60°C for 60 min under inert atmosphere of nitrogen yields alternating copolymer as evidenced by the values of r ₁ = 0.01 and r ₂ = 0.02. The kinetic expression was R_p ∝ [I]^0.75[MMA]^1.2[VP]^1.2. The overall activation energy is 45.4 kJ/mol. The FTIR bands of OCH₃ of MMA at 1725 cm^?1 and –C=O of N-VP at 1679 cm^?1, confirms the incorporation of both the monomers in the copolymer. The glass transition temperature of the copolymer is 133°C. The GPC data shows the polydispersity index at about 1.5. The ESR spectroscopy confirm phenyl radical responsible for initiation.     

Kinetics for copolymerization of methyl methacrylate with N‐cyclohexylmaleimide

The kinetics for the radical copolymerization of methyl methacrylate (MMA) with N‐cyclohexylmaleimide (NCMI) was investigated. The initial copolymerization rate R_p is proportional to the initiator concentration to the power of 0.54. The apparent activation energy of the overall copolymerization was measured to be 69.0 kJ/mol. The monomer reactivity ratios were determined to be r_NCMI = 0.42 and r_MMA = 1.63. R_p reduces slightly, and the molecular weight of the resultant copolymer decreases with increasing the concentration of the chain transfer agent N‐dodecanethiol (RSH). The more the transfer agent, the narrower the molecular weight distribution of the resulting copolymer. The following chain‐transfer constant of RSH for the copolymerization of MMA with NCMI in benzene at 50°C was obtained: C_s = 0.23. The glass transition temperature (T_g) of the copolymer increases with increasing f_NCMI, which indicates that adding NCMI can improve the heat resistance of Plexiglas. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1293–1297, 1999     

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     

Atom transfer radical copolymerization of methyl methacrylate with N‐cyclohexylmaleimide

Atom transfer radical polymerization has been applied to simultaneously copolymerize methyl methacrylate (MMA) and N‐cyclohexylmaleimide (NCMI). Molecular weight behaviour and kinetic study on the copolymerization with the CuBr/bipyridine(bpy) catalyst system in anisole indicate that MMA/NCMI copolymerization behaves in a ‘living’ fashion. The influence of several factors, such as temperature, solvent, initiator and monomer ratio, on the copolymerization were investigated. Copolymerization of MMA and NCMI in the presence of CuBr/bpy using cyclohexanone as a solvent instead of anisole displayed poor control. The monomer reactivity ratios were evaluated as r_NCMI = 0.26 and r_MMA=1.35. The glass transition temperature of the resulting copolymer increases with increasing NCMI concentration. The thermal stability of plexiglass could be improved through copolymerization with NCMI. © 2000 Society of Chemical Industry     

A study on the preparation and properties of alicyclic polyimides based on 3-carboxylmethylcyclopentane–1,2,4-tricarboxylic acid dianhydride

Alicyclic polyimides were prepared from 3-carboxylmethyl-cyclopentane–1,2,4-tricarboxylic acid dianhydride and conventional aromatic diamines. These polyimides possess good solubility in strong polar solvents, such as N-methyl pyrrolidone, N,N-dimethyl acetamide, N,N-dimethyl formamide, and m-cresol. They are transparent and colorless. The glass transition temperatures are about 181°C, and the initial thermal decomposition temperatures in N₂ were observed to be 441–477°C. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2105–2109, 1998     

Radiation-induced copolymerization of vinylphosphonic dichloride with methyl methacrylate and styrene

The γ-ray-induced copolymerization of vinylphosphonic dichloride (VPDC) with methyl methacrylate (MMA) and styrene (St) was studied at 25°C (liquid phase) and ?78°C (Solid phase). The reaction mechanisms are discussed. The reactivity ratios for the copolymerization of the VPDC–MMA system were determined as follows: The difference between the reactivity between the liquid-phase (25°C) and solid-phase (?78°C) copolymerization is mainly attributable to the r₂ value. The behavior of the liquid-phase copolymerization of the VPDC–St system was anomalous, the r₁ value being negative in the range from 0 to 80 mole-% of VPDC monomer. In the solid-phase (?78°C) copolymerization for the VPDC–St system, the reactivity ratios r₁ and r₂ were 0.097 and 1.6, respectively. The rate of copolymerization (R_p) at 25°C, for both the VPDC–MMA and VPDC–St systems, passes a maximum point at a certain monomer concentration, suggesting that the composition of copolymer is considerably affected by R_p. This phenomenon was interpreted by the assumption that an energy transfer reaction from VPDC monomer to the other vinyl compound can easily occur.     

Synthesis and characterization of alkali‐modified styrene‐maleic anhydride copolymer for dispersion of TiO2

A copolymer of styrene and maleic anhydride was synthesized by free radical polymerization at 80°C using N,N‐dimethylformamide (DMF) as solvent and benzoylperoxide as initiator. The monomer feed ratio of styrene to maleic anhydride was varied in the range of 1 : 1 : to 3 : 1. The polymer yield was found to decrease with increase in styrene in the feed. The molecular weight of copolymers which were formed by taking styrene to maleic anhydride ratio of 1 : 1, 2 : 1, and 3 : 1, as determined by Ostwald Viscometery were about 1862, 2015, and 2276 respectively. The acid values of abovementioned three copolymers were found to be 480, 357, and 295, respectively. The typical viscosity values of 20% solids in ammonical solution of copolymers formed by taking feed ratios of Sty : MAn as 1 : 1 and 2 : 1 were 26 and 136 cp, respectively. For the feed ratio 3 : 1, a gel was formed. The synthesized copolymers were hydrolyzed by alkalis, namely, NaOH, KOH, and NH₄OH. The dispersing ability of hydrolyzed styrene‐maleic anhydride (SMA) copolymers for dispersion of titanium dioxide was studied. The modified SMA copolymers were found to be effective dispersants for TiO₂. Among the three alkalis studied, the Sodium salts of SMA were found to give better dispersion. The copolymer having a 1 : 1 feed ratio showed the best dispersing ability for TiO₂ particles among the three ratios studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3194–3205, 2007     

Methacrylate/acrylate terminated derivatives of diglycidyl hexahydrophthalate: Synthesis,structural, and thermal characterization

Mono‐ or di(meth)acrylate‐terminated derivatives of diglycidyl hexahydrophthalate (ER) were prepared by reacting 1 : 1 or 1 : 2M ratio of ER and methacrylic acid or acrylic acid. These vinyl ester (VE) resins were characterized by determining epoxy equivalent weight, acid number, and molecular weight by gel permeation chromatography. Structural characterization was done by FTIR and ¹H NMR spectroscopy. In the ¹H NMR spectra of acrylate‐terminated VE resins, three proton resonance signals were observed in the region 5.8–6.4 ppm due to vinyl group while in methacrylate‐terminated VE resins only two proton resonance signals due to vinylidene protons were observed at 5.6–6.1 ppm. The Brookfield viscosity (room temperature (25 ± 2)°C) of these resins diluted with varying amounts of MMA was determined at 20 rpm. Curing behavior was monitored by determination of gel time and differential scanning calorimetry. An exothermic transition was observed in the DSC scans in the temperature range of (81–150)°C. Isothermal curing of MMA‐diluted VE resins containing AIBN as an initiator was done at 60°C for 2 h in N₂ atmosphere, and then heating for another 2 h in static air atmosphere. Thermal stability of isothermally cured resins in N₂ atmosphere was evaluated by thermogravimetric analysis. All cured resins decomposed above 310°C in single step. Thermal stability of the cured resins having acrylate end caps was marginally higher than the resins having methacrylate end groups. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Spreadsheets in copolymerization studies

A Lotus spreadsheet (LS) was utilized as part of a copolymerization study of methyl methacrylate (MMA) with N-phenylmaleimide (MP) and with some derivatives of MP, namely N-o-chlorophenylmaleimide (MOCP), N-p-tolylmaleimide (MPT), and N-o-tolylmaleimide (MOT). The use of LS provided a very rapid method to obtain values of copolymerization parameters which were in very good agreement with non-spreadsheet reported values. Further, a novel LS macro was developed which could be employed to ascertain the shape of the copolymer composition curve (copolymer composition as a function of monomer composition). Monomer reactivity ratios, r₁ and r₂, were determined as well as values of semi-empirical copolymerization parameters Q and e. An attempt was made to correlate the monomer structures used with the values of Q and e. An empirical decomposition temperature index (DTI) was also devised to measure the thermal stability of copolymers of MMA and MP as a function of MP content. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 891–900, 1997     

Radical copolymerization between methyl methacrylate and N‐cyclohexylmaleimide with thiol as an inifer

N‐dodecanethiol (RSH) was found efficient to initiate the radical copolymerization of methyl methacrylate (MMA) with N‐cyclohexylmaleimide (NCMI) at 40–60°C. The initial copolymerization rate, R_p, increases respectively with increasing [RSH] and the mol fraction of NCMI in the comonomer feed, f_NCMI. The molecular weight of the copolymer decreases with increasing [RSH]. The initiator transfer constant of RSH was determined to be C_I = 0.21. The apparent activation energy of the overall copolymerization was measured to be 46.9 kJ/mol. The monomer reactivity ratios were determined to be r_NCMI = 0.32 and r_MMA = 1.35. The glass transition temperature of the copolymer increases obviously with increasing f_NCMI, which indicates that adding NCMI may improve the heat resistance of plexiglass. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1417–1423, 1999     

Synthesis and characterization of oil sorbers based on docosanyl acrylate and methacrylates copolymers

Docosanyl acrylate (DCA) monomer was copolymerized with different monomer feed ratios of cinnamoyloxy ethyl methacrylate (CEMA) or methyl methacrylate (MMA) monomer to produce different compositions for DCA/CEMA or DCA/MMA copolymer with low conversions.¹H NMR spectroscopy was used to confirm the copolymer structure. DCA was crosslinked with different mol % of CEMA or MMA using dibenzoyl peroxide as initiator and various weight percentages of either 1,1,1‐trimethylolpropane triacrylates or 1,1,1‐trimethylolpropane trimethacrylates crosslinkers. The effects of monomer feed composition, crosslinker concentration, and the hydrophobicity of the copolymer units on swelling properties of the crosslinked polymers were studied through the oil absorbency tests. The network parameters, such as polymer solvent interaction (χ), effective crosslink density (υ_e), equilibrium modulus of elasticity (G_T), and average molecular weight between crosslinks (M_c), were determined and correlated with the structure of the synthesized copolymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A synthesized semi-aromatic copolyamaide through synergy of three different kinds of monomers: Toward high transparency,excellent heat resistance and melt flowing property

To fabricate the low-cost transparent polyamide with high heat resistance and good melt flowing property simultaneously is a huge challenge in many high-end fields due to the contradiction between these two properties. In order to balance this contradiction, in this paper, by using isophthalic acid (IPA, aromatic monomer), 4,4′-methylenebis(cyclohexylamine) (PACM, alicyclic monomer) as rigid stereoscopic monomers, 1,6-hexanediamine (HMD, aliphatic monomer) as the flexible monomer, a series of transparent poly(hexamethylene isophthalamide/poly(m-benzoyl4,4′-methylenebis(cyclohexylamine)) (PA6I/PACMI) with rigid and stereoscopic structure (corresponding to the large distance between adjacent molecular chains) were successfully synthesized. The results indicated that the newly synthesized PA6I/PACMI copolymer has an intrinsically amorphous structure and high optical transparency, which could reach as high as 90%. Furthermore, the highest glass transition temperature (T_g) of the copolymer is over 153.9°C, at the same time, the copolymer also possesses excellent melt flowing property, which can be melt processed easily. Therefore, the newly synthesized copolymer has great advantages in many fields, and it can also shed light on the design and fabrication of high-performance materials.     

Preparation and properties of bismaleimide resins of aromatic sulfone ether diamine

Aromatic sulfone ether diamine, bis[4-(4-aminophenoxy)phenyl]-sulfone (SED), was prepared by the nucleophilic aromatic substitution of 4,4′-dichlorodiphenylsulphone by p-aminophenolate. The reaction was conducted in the presence of excess potassium carbonate as a weak base, toluene as the dehydrating agent and N-methylpyrrolidone as the dipolar aprotic solvent. SED showed good solubility in common organic solvents, such as dioxan, tetrahydrofuran, butanone and acetone. SED was reacted with maleic anhydride to obtain aromatic sulfone ether bismaleimide, bis[4-(4-maleimidophenoxy)phenyl]-sulfone (SEM). The compounds were characterized by FTIR and ¹H NMR analysis. Furthermore, copolymer resins of SED with 4,4′-bismaleimidodiphenyl methane (BMI) and SEM were prepared. After curing, crosslinked resins with better thermal stability resulted. The temperature at maximum rate of weight loss (T_max) and the heat-resistant temperature index (T_i) in air were found to be 426°C, 208°C and 579°C, 221°C for BMI/SED and SEM/SED resins, respectively. Compared with the corresponding 4,4′-diaminodiphenyl methane (DDM) system, BMI/SED and SEM/SED showed a slight decrease in T_max and T_i SED-modified BMI/amine resin based glass cloth laminates for printed circuit boards showed higher mechanical properties than those of the corresponding unmodified system. With SED instead of the original amine component in 3–5% weight fraction, the tensile strength, flexural strength and impact strength of the laminates increased markedly. Meanwhile, the stripping strength and weld resistance were also improved by the addition of SED.     

Studies on syntheses and properties of episulfide‐type optical resins with high refractive index

A series of novel high refractive index episulfide‐type optical resins were prepared by ring‐opening copolymerization of bis(β‐epithiopropylthioethyl) sulfide (BEPTES) with episulfide derivative of diglydicyl ether of bisphenol A (ESDGEBA) and 2,4‐tolylene diisocyanate (TDI), respectively, in the presence of triethylamine as a curing catalyst. The episulfide monomers, BEPTES and ESDGEBA, were synthesized from their corresponding epoxy compounds, respectively. The cured transparent resins exhibit high refractive index (n_d > 1.63) and relatively low dispersion. The refractive index (n_d) and Abbe's number (ν_d) of the BEPTES/ESDGEBA curing system increased linearly with the weight content of BEPTES monomer in the range from 1.633 and 34.0 for the copolymer with 10 wt % of BEPTES to 1.697 and 38.1 for the homopolymer of pure BEPTES. For the BEPTES/TDI curing system, the refractive index and Abbe's number varied linearly with the molar ratio of BEPTES to TDI from 1.652 and 28.7 to 1.669 and 34.6. High glass‐transition temperatures (T_g > 130°C) of the cured BEPTES/TDI resins were observed, which indicate that the cured BEPTES/TDI resins possess a good heat resistance. The optical, physical, and thermal properties of the episulfide‐type cured optical resins were also discussed in this study. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2426–2430, 2003     

Synthesis of substituted polymethylenes from acenaphthylene by radical polymerization and copolymerization

Radical polymerization of acenaphthylene (Ace) as a 1,2-disubstituted ethylene was investigated. It was found that the polymerization rate (R_p) was expressed as follows: R_p = k[Ace]^1.0[AIBN]^0.68, and that the overall activation energy was 113 kJ/mol for polymerization with 2,2'-azobisisobutyronitrile (AIBN) in benzene at 50–70°C. Poly(Ace) obtained was characterized by NMR spectroscopy and GPC. Some substituted copolymethylenes were also prepared by radical copolymerization of Ace with other 1,2-disubstituted ethylenes, that is, maleic anhydride, diisopropyl fumarate, and N-cyclohexylmaleimide. The monomer reactivity ratios were determined from comonomer–copolymer composition curves.     

Novel organosoluble poly(amide‐imide‐imide)s synthesized from new tetraimide‐dicarboxylic acid by condensation with 4,4′‐oxydiphthalic anhydride, 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene,trimellitic anhydride,and various aromatic diamines

A new monomer of tetraimide‐dicarboxylic acid (IV) was synthesized by starting from ring‐opening addition of 4,4′‐oxydiphthalic anhydride, trimellitic anhydride, and 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene at a 1:2:2 molar ratio in N‐methyl‐2‐pyrrolidone (NMP). From this new monomer, a series of novel organosoluble poly(amide‐imide‐imide)s with inherent viscosities of 0.7–0.96 dL/g were prepared by triphenyl phosphite activated polycondensation from the tetraimide‐diacid with various aromatic diamines. All synthesized polymers were readily soluble in a variety of organic solvents such as NMP and N,N‐dimethylacetamide, and most of them were soluble even in less polar m‐cresol and pyridine. These polymers afforded tough, transparent, and flexible films with tensile strengths ranging from 99 to 125 MPa, elongations at break from 12 to 19%, and initial moduli from 1.6 to 2.4 GPa. The thermal properties and stability were also good with glass‐transition temperatures of 236–276°C and thermogravimetric analysis 10 wt % loss temperatures of 504–559°C in nitrogen and 499–544°C in air. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2854–2864, 2006