Thermal Stability Of Copolymers Research Articles

Physico-Chemical and Light-Induced Properties of Quinoline Azo-dyes Polymers.

We present investigation of optical and photochromic properties as well as of surface quality of thin films of novel methacrylic polymers with 8-hydroxyquinoline azo-dyes in side-chain. Additionally, thermal stability of polymer powders was examined and their glass transition temperature was determined. Optical properties (extinction coefficient and refractive index) were determined by spectroscopic ellipsometry (SE) combined with absorbance measurements. Photoresponsive behavior was investigated by determination of photoisomerization rates under irradiation with unpolarized 365 nm light, as well as by conduction of holographic grating inscription experiment. Thin film quality was determined by atomic force microscopy (AFM) measurements. Thermal analysis was performed by thermogravimetric (TG), derivative thermogravimetric (DTG) and differential scanning calorimetry (DSC) measurements. We found that optical properties as well as photoisomerization rates of investigated polymers are dependent on the substituent in the para position of the phenyl ring. Surface relief grating inscription was successfully generated only for materials with chromophores containing dimethylamino (N(CH3)2) and methyl (CH3) substituents, but all materials exhibited birefringence grating in the bulk. Surface of most thin films was very smooth, but its quality was impaired by neutral (H) as well as carboxyl (COOH) substituent. Thermal stability of copolymers with side-chain chromophores was improved compared to pure poly(methyl methacrylate) (PMMA).

Homo‐ and random copolymerizations of ω‐pentadecalactone with ε‐caprolactone using isothiourea‐based dual catalysis

ABSTRACTIn this study, the catalytic behavior of dual catalysis based on isothioureas (ITUs) for ring‐opening polymerization (ROP) of macrolactone ω‐pentadecalactone (PDL) and its copolymerization with ε‐caprolactone (CL) has been investigated in detail. In the presence of benzyl alcohol (BnOH) initiator, 2,3,6,7‐tetrahydro‐5H‐thiazolo[3,2‐a]pyrimidine (THTP) acted as a representative organic compound, which coupled with magnesium halides (MgX2) as cocatalysts and catalyzed the polymerization in toluene at 70 °C. Under suitable conditions, an array of polymers with controlled molecular weights and relatively narrow molecular weight distributions were synthesized. The formation of homopolymers and copolymers with different architectures was verified using GPC, DSC, NMR, and matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐ToF) mass. The MALDI‐ToF mass spectrometry (MS) analysis of poly(ω‐pentade‐calactone) (PPDL) provided direct evidence for the successful initiation of ROP of PDL using BnOH to obtain linear PPDL with a very small amount of oligomer. The NMR analysis indicated that the arrangements of PDL and CL units in the copolymer chains were completely random. The thermal stability of copolymers was composition dependent and increased with the increase in the content of PDL unit. Furthermore, the proposed polymerization mechanism is a dual catalytic mechanism. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019

Surface Energy and Thermal Stability Studies of Poly(dimethyl siloxane)–Poly(alkyl(meth)acrylate) Copolymers

ABSTRACTThe correlation between the surface energy and thermal stability of polymers plays an important role in engineering of plastic materials. In this work, microstructural characteristics of copolymers of poly(dimethyl siloxane) with benzyl methacrylate, ethyl methacrylate, and methyl acrylate are correlated with their surface energy and thermal stability. The poly(dimethyl siloxane) segments in the copolymer chains affected the hydrophobic behavior. The surface energy of the synthesized copolymers decreased by increasing segments of alkyl methacrylates. The thermal stability of copolymers suggesting that heat resistance of poly(dimethyl siloxane) copolymers used in this correlation can be improved by adjusting the units of alkyl methacrylates in copolymers.

Effect of butyl lactate methacrylate content on the properties of acrylic acid copolymers

In the present work, the effect of butyl lactate methacrylate (BLM) content on the properties of acrylic acid (AA) copolymers was investigated. The BLM monomer was synthesized by reacting butyl lactate with methacrylic acid through azeotropic distillation method, which was confirmed by Mass spectrometric technique. Copolymers were synthesized by free-radical solution polymerization technique to obtain poly(BLM-co-AA). BLM monomer and copolymers were characterized by Fourier transform infrared (FTIR), 1H-nuclear magnetic resonance (1H-NMR) and proton decoupled 13C-NMR spectroscopic techniques. The Finemann-Ross method was used to determine the reactivity ratio of AA and BLM and the values were found to be 0.79 and 0.39, respectively. The wide angle X-ray scattering (WAXS) studies exhibited that the increase in BLM content in copolymers, shifted the amorphous halo from 21.34° to 15.39° and also increased the average molecular interchain spacing (〈R〉) from 5.20 to 7.18 A, which was calculated from 2θ values of amorphous halo of copolymers. Moisture absorption of polymers followed Fickian absorption. Depending upon the copolymer composition, relative humidity and time, the moisture absorption of copolymers can be tuned to a wide range from 11 to 35% (wt/wt). Glass transition temperature of copolymers decreased from 106 to 72.1°C with increase in BLM content. Copolymers were thermally stable up to 150°C and thereafter exhibited three-step thermal degradation in nitrogen atmosphere. Thermal stability of copolymers can be explained on the basis of 〈R〉 value.

Starch-g-poly(benzyl methacrylate) copolymers

The physicochemical properties such as swelling in polar and non-polar solvents, moisture resistance, chemical resistance, ability for gelatinization and the thermal properties along with the evolution of volatile decomposition products of some starch-g-copolymers obtained through the grafting of benzyl methacrylate monomer onto potato starch have been studied. The chemical structure of copolymers was confirmed using ATR–FTIR analysis. The prepared materials were characterized by completely different properties than unmodified potato starch due to the covalent bonding of poly(benzyl methacrylate) chains onto starch backbone. The copolymers were not able to gelate; however, they exhibited higher swelling in non-polar solvents, lower swelling in polar solvents and higher resistance toward moisture, acid and base conditions than unmodified potato starch. In addition, DSC analysis showed that T g of copolymers was shifted to a little higher values as compared to T g of poly(benzyl methacrylate). The thermal stabilities of copolymers and potato starch were comparable. Their decomposition took place in two main stages connected with the emission of various volatile decomposition products (CO2, CO, H2O, CH4, aldehydes, alcohols, furan derivatives, acids, benzyl methacrylate) in inert atmosphere as it was confirmed based on the simultaneous TG/DSC/FTIR analysis.

Synthesis of graft copolymers onto starch and its semiconducting properties

Literature review has revealed that, although there are studies about grafting on natural polymers, especially on starch, few of them are about electrical properties of graft polymers. Starch methacrylate (St.met) was obtained by esterification of OH groups on natural starch polymer for this purpose. Grafting of synthesized N-cyclohexyl acrylamide (NCA) and commercial methyl methacrylate (MMA) monomers with St.met was done by free radical polymerization method. The graft copolymers were characterized with FT-IR spectra, thermal and elemental analysis. Thermal stabilities of the graft copolymers were determined by TGA (thermo gravimetric analysis) method and thermal stability of the copolymers is decreased via grafting. The electrical conductivity of the polymers was measured as a function of temperature and it has been observed that electrical conductivity increases with increasing temperature. The absorbance and transmittance versus wavelength of the polymers have been measured.

Dielectric properties of lithium-perchlorate-filled acrylonitrile-hexyl methacrylate copolymer films

A series of poly(acrylonitrile-co-hexyl methacrylate), PAN-co-PHMA, copolymers with various hexyl methacrylate (HMA) contents were synthesized by emulsion technique. The incorporation of HMA units into the copolymers was confirmed by Fourier transform infrared and proton nuclear magnetic resonance (1H-NMR) spectroscopy. Glass transition temperatures (Tg) and thermal decomposition temperatures of copolymers were determined by differential scanning calorimetry and thermogravimetric analysis. The Tg of copolymers were lowered monotonically by increasing HMA content, while thermal stabilities of copolymers were enhanced. The frequency dependence of dielectric properties of three different amounts of LiClO4 salt doped copolymer films was investigated. The influence of molar fraction of HMA on dielectric constant and ac-conductivity of copolymer films was examined. Samples with higher HMA contents showed better stability and conductivity, as a result of increase in free volume and the mobility of the dipoles. The ac conductivity of copolymers was also improved by increasing LiClO4 salt which was due to the existence of more charge carriers. PAN(88)-co-PHMA(12) copolymer with 1.5 mol% of lithium salt exhibited ionic conductivity of the 7.8 × 10−4 S/cm at 298 K. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Synthesis and surface properties of novel fluoroalkylsilyl methacrylate copolymers

Abstract The syntheses of novel mono(1H,1H,2H,2H-tridecafluorooctyl) dimethylsilylpropyl methacrylate (MFSA), bis(1H,1H,2H,2H-tridecafluorooctyl)methylsilylpropyl methacrylate (BFSA) and tris(1H,1H,2H,2H-tridecafluorooctyl)silylpropyl methacrylate (TFSA) were achieved in two steps each in good yields. These fluoroalkylsilyl methacrylate monomers (MFSA, BFSA and TFSA) readily reacted with methyl methacrylate (MMA), butyl acrylate (BA), hydroxyethyl methacrylate (HEMA) to form their corresponding fluoroalkysilyl methacrylate copolymers via continuous emulsion polymerization. The structures of fluoroalkylsilyl methacrylate monomers and copolymers were characterized by FT-IR, 1H NMR, 13C NMR and 19F NMR. The stability of copolymer emulsions was determined by measuring their particle size and zeta potential, and the thermal stability of copolymers was also evaluated by using thermo-gravimetric analysis. In addition, it was observed that improving fluorine content, increasing the packing density of fluoroalkylsilyl segments, and annealing process could enhance the excellent water and oil repellency of fluoroalkylsilyl methacrylate copolymers. The surface free energies of copolymer films were calculated. Moreover, an enrichment of fluoroalkyl chains at the copolymer surface was directly verified by measuring contact angles and using atomic force microscopy.

Homo- and Copolymers of Decyl Methacrylate as Performance Additives for Lube Oil

Homopolymer of decyl methacrylate and its copolymer with styrene at different concentrations using two types of initiators (benzoyl peroxide [BZP] and azobisisobutyronitrile [AIBN]) were synthesized. All the prepared polymers are characterized by FT-IR and NMR. The molecular weight was determined by gel permeation chromatography. The performance of the prepared polymers in different base oils were evaluated as viscosity modifier, also known as viscosity index improver and pour point depressant. The molecular weight of homopolymer prepared by using BZP initiator is higher than homopolymer prepared by using AIBN initiator but molecular weight of copolymers prepared by BZP are lower than copolymers prepared by AIBN initiator. The theromogravimetric analysis value of the prepared polymers was determined by standard ASTM method and it is found that the thermal stability of copolymers decrease with increasing the styrene content.

Copolymers of 7-Methoxy-2-Acetyl Benzofuryl Methylmethacrylate With Styrene: Synthesis, Characterization, Reactivity Ratios and Determination of Kinetic Parameters With Thermogravimetric Analysis

The 7-methoxy-2-acetyl benzofuryl methylmethacrylate (MABMM) monomer was synthesized by reacting 7-methoxy-2-bromo acetyl benzofurane with sodium methacrylate in acetonitrile solvent at 70°C in the presence of triethylbenzylammoniumchloride (TEBAC). The monomer was characterized by FTIR, 1H-and 13C-NMR spectral studies. Reactivity ratios for the copolymers 7-methoxy-2-acetyl benzofuryl methylmethacrylate (MABMM)-co- styrene (ST) are reported. Copolymers were prepared by free radical polymerization using 2,2′-azobisisobutyronitrile (AIBN) as an initiator at 70°C in 1,4-dioxane solution. FTIR, 1H-and 13C-NMR spectral studies and gel permeation chromatography (GPC) were used the copolymer characterization. The monomer compositions in the copolymer were determined by elementel analyses and the reactivity ratios (ri) were calculated applying diverse linear methods, namely Finemann-Ross (FR) and Kelen-Tüdös (KT) and the nonlinear error invariable model method of a computer program RREVM. By using the latter pr°Cedure, the values of the reactivity ratios were estimated as 2.74 and 0.69 for the system MABMM (1) and ST (2), respectively. These values suggest the formation of nearly-alternating copolymers in the systems. Molecular weights were determined by gel permeation chromatography (GPC). The polydispersity indices of the polymers determined using suggest a strong tendency for chain termination by disproportionation. The glass transition temperature of the polymers were investigated by Shimadzu DSC-60 and the apparent thermal decomposition activation energies (Ed) were calculated by the Ozawa method using the Perkin-Elmer TGA thermobalance, respectively. Tg increases when the concentration of polar monomer (MABMM) in the copolymer increases. It was observed that thermal stabilities of copolymers increased with increasing of MABMM content in copolymers.

Synthesis, structure and thermal properties of poly(A-block-B-block-A) copolymer based on biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and amorphous polystyrene

A series of poly(A-block-B-block-A) copolymers based on biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and amorphous polystyrene (PS) were synthesised by atom transfer radical polymerisation (ATRP). The chemical structure, molecular weight and distribution were systematically characterised by Fourier transform infrared, 1H nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). The melting and crystallisation behaviours, and thermal stabilities of copolymers were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA); the degradation activation energy was calculated by Horowitz–Metzger method. Results showed that the maximum yield of triblock copolymer was 88%. DSC curves revealed that the triblock copolymers had their cold crystallisation temperature from 50·83 to 65·67°C, and the crystallinity from 55·60 to 12·60. TG curves showed that the thermal stabilities of triblock copolymers were enhanced, and its degradation activation energy decreased from 428 to 197 kJ mol−1.

Enhanced Thermal Stability and Flame Retardancy of a Novel Transparent Poly(Methyl Methacrylate)-Based Copolymer

A novel poly (methyl methacrylate) (PMMA) based copolymer was synthesized by bulk copolymerization of methyl methacrylate (MMA) and a phosphorus-containing monomer, acryloxyethyl phenoxy phosphorodiethyl amidate (AEPPA). The chemical structure of AEPPA was confirmed by FTIR,1H NMR and31P NMR. The structure of copolymers was characterized using FTIR. TGA results indicate that the thermal stability of copolymers was remarkably enhanced with the addition of APEEA. LOI and MCC results suggest that the flame retardancy of copolymers was also improved. Detailed flame-retardant mechanism is proposed. The char formation during degradation caused by APEEA plays a key role in the property improvements.

Novel cross-linking poly(ethylene oxide) grafted poly(1-hydroxy-2-methoxyphenol) copolymers by secondary polymerization

Anionic ring-open polymerization of ethylene oxide (EO) functionalized 1-hydroxy-2-methoxybenzene (HMOB) monomer 1-(2,3-epoxypropyl)-2-methoxybenzene (EPMOB) led to the formation of the precursor polymer oligo(1-(2,3-epoxypropyl)-2-methoxybenzene) (OEPMOB). Poly(OEPMOB-co-1-hydroxy-2-methoxybenzene) films P1, P2, P3, and P4 were successfully achieved by secondary electrochemical copolymerization of the monomer mixtures OEPMOB/HMOB with different mass ratios of 3:1, 2:1, 1:1, and 1:2, respectively. The possibility of inter- and intramolecular polymerization resulted in a cross-linking conjugated network microstructure. A series of experiments were carried out to investigate the influence of monomer mass ratios on the electrochemical copolymerization and other properties of copolymer films. UV–vis, FT-IR, and 1H NMR were used to characterize the structure of copolymers. Fluorescence spectroscopic studies revealed that the copolymers partly dissolved in DMSO were all good blue light-emitters, with strong emissions at 392nm in the doped state. Since EO and HMOB units were introduced into the skeletal backbone, thermal stability of copolymers was improved in comparison with their corresponding homopolymers.

Thermal and viscoelastic properties of novel epoxy-dicyclopentadiene-terminated polyesters-styrene copolymers

This article presents the studies on the thermal and viscoelastic properties of novel epoxy-dicyclopentadiene-terminated polyesters-styrene copolymers. The novel materials were prepared during a three step process including the addition reaction of maleic acid to norbonenyl double bond of dicyclopentadiene; polycondensation of acidic ester of dicyclopentadiene, cyclohex-4-ene-dicarboxylic anhydride, maleic anhydride, and suitable glycol: ethylene, diethylene, or triethylene glycol; and the epoxidation process of prepared polyesters. It allowed obtaining novel epoxy-dicyclopentadiene-terminated polyesters which were successfully used as a component of different styrene content (10–80 mass%) copolymers. The influence of the structures of polyester and styrene content on the cross-linking density (v e), tgδ max, tgδ max height, storage modulus (E′ 20 °C), FWHM values as well as the thermal stability of copolymers was evaluated by TG, DSC, and DMA analyses and discussed.

Synthesis of N-(2,4,5-trichlorophenyl) Acrylamide Copolymer Emulsions and their Antibacterial, Thermal and Mechanical Properties

N-(2,4,5-trichlorophenyl) acrylamide (CPAM) monomer was synthesized and copolymerized with BA and MMA using varying concentration of CPAM monomer via seed batch emulsion polymerization technique. The resultant CPAM copolymers were characterized by FT-IR spectroscopy. Thermal behaviors of CPAM copolymers were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was observed that glass transition temperature and thermal stability of copolymers increases with increase in CPAM content in copolymers. Also the CPAM copolymers were subjected to evaluate Limiting Oxygen Index (LOI) and Mechanical properties. The LOI and mechanical properties results showed that as the CPAM concentration increases, its Limiting Oxygen Index and mechanical properties increases. The CPAM copolymers were used to screen their antibacterial activity against various microorganisms (E.Coli, S. Aureus, M. Luteus, and B. Subtilis.) and it was observed that its antibacterial activity has a direct influence on the CPAM concentration.

Thermal Stability and Thermal Degradation Kinetics of Poly(Trimethylene-co-Butylene Terephthalate) Copolymers

The thermal stability and thermal decomposition kinetics of poly(trimethylene-co-butylene terephthalate) (PTBT) copolymers in nitrogen were studied by means of thermogravimetry. The PTBT copolymers had good thermal stability in nitrogen and the introduction of copolymer component had a slight influence on the thermal stability of copolymers. The mass loss of PTBT copolymer was accomplished in one main mass loss stage and one small weight loss in the early stage of decomposition. The PTBT copolymers started to decompose at ≈350.0°C and completed decomposition at ≈440.0°C with the heating rate of 5°C/min. The characteristic degradation temperatures of PTBT copolymers shifted toward higher temperatures with increasing heating rates and poly(trimethylene terephthalate (PTT) content. Furthermore, various degradation methods, including the Ozawa–Flynn–Wall method, Friedman's method, and Kissinger's method, were used to determine the activation energies of copolymers. The three methods were applicable to the kinetic description of thermal degradation of PTBT copolymers. The thermal activation energies obtained by three methods were in satisfactory conformity. The thermal degradation kinetics of copolymers could be interpreted in terms of multi-step degradation mechanisms. It was shown that the thermal stability of PTBT copolymers increased with increase in PTT content. Copolymers with higher PTT content showed higher degradation temperature and thermal activation energy. A general activation energy range of 180–200 kJ/mol was suggested for the processing and use of PTBT copolymer fibers.

Thermal Properties and Electrical Conductivity of Graft Copolymers from Polystyrene and Polyvinyl Propionate with Polyaniline

AbstractA synthesized graft copolymer from polystyrene (PS) and polyvinyl propionate (PVPr) with polyaniline (PANi) with suitable electrical properties, thermal resistance, solubility and processability was optimized. Samples were prepared in the form of smooth and thin films. Four-point probe method was adapted to examine electrical DC conductivity. It was found that the electrical conductivity and thermal stability of copolymers were increased, but their processability and solubility decreased when PANi increased. Thermal stability of copolymers was investigated by Differential Scanning Calorimetry (DSC) and Thermal Gravimetrical Analysis (TGA). The prepared copolymers were much more thermally stable, soluble, flexible and ability to form a film than polyaniline, polystyrene and polyvinyl propionate. An irreversible exothermic transition was observed by DSC, which is believed to be an indication of cross-linking. Percentage of grafted PANi electrical conductivities of PS-g-PANi and PVPr-g-PANi have been examined and produced conductivities, 3.3 × 10−2 and 4.6 × 10−2 S/cm respectively.

Modification of styrene polymer by attaching suitable groups as side chain

AbstractChemical modification of inexpensive commercial polymers, such as styrene, is a safe methodology to obtain new copolymers. The 4-chloromethyl styrene (CMS) was copolymerized with styrene (in various mole ratios) by free radical polymerization method at 70 ºC using α,α-azobis(isobutyronitrile) (AIBN) as an initiator. The azide ion was covalently attached to the obtained copolymers with replacement of all the chlorine atoms in CMS units. The 1,3-dipolar click cycloaddition reaction between azido polymers and dimethyl acetylene dicarboxylate (DMAD) yielded polymers with 1,2,3-triazoles in side chain. The polymers, obtained in quantitative yields, were characterized by FT-IR and 1H NMR spectroscopy; thermogravimetric analysis (TGA) and GPC studies. The thermogravimetric analysis (TGA) indicated that the thermal stability of copolymers increases with incorporation of 1,2,3-triazole groups in side chains of copolymers.

Novel acrylic copolymers: synthesis, characterization and antimicrobial studies.

AbstractThe monomer 2,4-dichloro phenyl acrylate (2,4-DCPA) was synthesized from 2,4-dichlorophenol and characterized by conventional methods. The homopolymers of 2,4-DCPA and its copolymers with 8-quinolinyl methacrylate (8- QMA) in different feed ratio were prepared by free radical polymerization using dimethyl formamide (DMF) as a solvent and 2,2’-azobisisobutyronitrile (AIBN) as an initiator. The resulting polymers were characterized by Infrared Spectroscopy. UV spectral data were employed to obtain the reactivity ratios of the monomers, 2,4-DCPA and 8-QMA. The results showed that 2,4-DCPA is more reactive than 8- QMA. Average molecular weights and intrinsic viscosities determined by Vapour pressure osmometer (VPO) lies in the range of 7900 to 10890 and 0.021-0.036 dl.g-1 respectively. Thermal analysis shows that thermal stability of copolymers increases with the increase of 2,4-DCPA. The copolymers also showed antimicrobial activity which increased with increase in 8-QMA content.

THERMAL DEGRADATION OF IMIDE-CONTAINING SILOXANE-URETHANE COPOLYMER

Two scries of copolymers, siloxane-urethane and imide-containing siloxane-urethane copolymers (SiU and SiUI copolymers), were synthesized from 4,4'-diphenylmethane diisocyanate (MDI), OH-terminated polydimethylsiloxane (PDMS) and chain extender 1,4-butanediol (1,4-BD) or pyromellitic dianhydride (PMDA) in one-step process. SiU copolymer had four stages of degradation. The degradation in the first, second, third and fourth stage were caused by the decomposition of urethane resulted from MDI and 1,4-BD at 250∼320 °C, urethane resulted from MDI and PDMS at 320∼420 °C, linear PDMS at 420∼550 °C, and macro-cyclics PDMS at 550∼620 °C, respectively. SiUI copolymer had three stages of degradation caused by decomposition of urethane resulted from MDI and PDMS, linear PDMS, and PMDA. The imide group and content greatly affected the degradation behavior of copolymer. The influence of components, hard and soft contents on degradation characterization and thermal stability of copolymer at 220 °C and 450 °C were investigated by the isothermal degradation measurements.