The thermal stability of some poly(di-aryl itaconates)

Summary The non-oxidative thermal stability of poly(di-aryl itaconates) was established by thermogravimetric analysis. The polymers investigated were poly(diphenyl itaconate) (PDPhI), poly(di-ortho-, meta- and para-tolyl itaconates) (PDoTI, PDmTI, PDpTI) and poly(dibenzyl itaconate) (PDBzI). The shapes of the DTG curves indicated that at least two reactions were involved in the degradation mechanisms. Carbonaceous residues were registered in all polymers. Preliminary thermal degradation experiments showed that the polymers decomposed mainly by depolymerisation with side chain scission registered in the cases of PDoTI and PDBzI. All polymers except PDBzI crosslinked slightly at lower degradation temperatures.     

Radical polymerization of itaconic anhydride and reactions of the resulting polymers with amines and alcohols

Itaconic anhydride was polymerized in the presence of a radical initiator under various conditions. The bulk polymerization at 75°C yielded polymer with molecular weight of more than 20000. The reactions of the resulting polymer with water and alcohols gave poly(itaconic acid) and its esters, respectively. The polymers prepared by such reactions were found to have similar thermal properties to those prepared by homopolymerizations of the respective itaconic acid derivatives. Poly(N-substituted itaconomic acid)s, which are difficult to obtain by direct polymerization of their monomers, were prepared by the reactions of poly(itacononic anhydride) with amines. Copolymerizations of itaconic anhydride with electron-donating monomers, styrene and isobutyl vinyl ether, gave alternating copolymers which were then converted by esterification to the respective copolymers of dialkyl itaconates with such electron-donating monomers.     

Poly(benzoxazine-co-urethane)s: A new concept for phenolic/urethane copolymers via one-pot method

Historically, applications for traditional phenolic resin/polyurethane materials are limited due to the inherently weak thermal stability of urethane-phenolic linkage and slow reaction rate. A novel concept has been developed to produce phenolic resin/polyurethane copolymers via benzoxazine chemistry. Through one-pot synthesis, a series of linear poly(benzoxazine-co-urethane) materials has been synthesized via the reaction of a newly developed dimethylol functional benzoxazine monomer with 4,4′-methylene diphenyl diisocyanate and poly(1,4-butyleneadipate). The structure of the copolymers has been characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). The copolymers in the film forms have been further thermally treated for crosslinking to produce crosslinked poly(benzoxazine-co-urethane) via the ring opening polymerization of cyclic benzoxazine moieties in the main-chain. The tensile properties of the films have been studied and compared with those of traditional high performance materials. The thermal properties of the crosslinked copolymers have also been studied by dynamic mechanical analysis, and thermogravimetric analysis (TGA).     

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

The 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.     

Synthesis of a series of metallophthalocyanine end-capped poly(aryl ether sulfone)s from a dicyanoarylene group containing biphenol

A novel biphenol monomer, 1,4-bis(4-hydroxy-phenyl)-2,3-dicyanonaphthlene was prepared in high yield in a two-step reaction from reduced phenolphthalein containing a hydro cyanic group by an improved method. A series of uncapped copolymers were synthesized using this bisphenol. In addition, a series of thermally stable poly(arylene ether)s having covalently bound metal (II) naphthalocyanine units were synthesized by the reaction of dicyanoarylene containing poly(aryl ether)s with excess amounts of 1,2-dicyanobenzene and the corresponding metal salt in quinoline. The copolymers synthesized had high glass transition temperature and exhibited good thermal stability. Also, these polymers were found to have good solubility and capable of forming tough films. These colored polymers showed visible absorption maxima in the range of 538-715 nm.     

Stabilized polymeric nanoparticle from amphiphilic mPEG-b-polyaspartamides containing ‘click’ functional groups

The synthesis of a series of poly(ethylene glycol) and polyaspartamide-based block copolymers containing azide and alkyne function groups and its micelle formation in aqueous solution were described. The self-assembly behavior of these amphiphilic copolymers in aqueous media to form nanosized micelle and the core-crosslinking reaction to convert them to stable nanoparticle were investigated. The particle size distributions were measured by dynamic light scattering. The resulting nanogel, prepared by click reaction within the mixed micelle core, has been shown to exhibit stability upon dilution and also in the presence of SDS, a small-molecule surfactant, suggesting the potential use as carrier for current drug delivery system.     

Synthesis and characterization of polysulfone–poly(alkylene oxide) block copolymers containing poly(dimethylsiloxane)

Block copolymers of polysulfone–poly(alkylene oxide)–poly(dimethylsiloxane) have been prepared by the addition of preformed α,ω-bis(hydrogensilyl)poly(dimethylsiloxane) oligomers to allyl end-capped poly(alkylene oxide)–polysulfone. The hydrosilylation reaction, catalyzed by platinum, was employed for incorporation of the siloxane chain into the copolymers in a 1 : 1 or 1 : 2 molar ratio of Si–H-terminated polydimethylsiloxane to allyl end-capped polysulfone. The products were characterized by IR, ¹H-NMR, and gel permeation chromatography. The thermal stability was determined by thermogravimetric analysis. Differential scanning calorimetry was used to investigate microphase separation in the block copolymers. © 1996 John Wiley & Sons, Inc.     

Synthesis and Characteristics of Novel Poly(Imide Siloxane) Segmented Copolymers

New poly(imide siloxane) copolymers for possible use as tough environmentally stable structural matrix resins and structure adhesives have been prepared. Thus, 3,3'-4,4'-benzophenone tertracarboxylic dianhydride was reacted with various Mn aminopropyl-terminated polydimethylsiloxane oligomers and a meta-substituted diamine “chain-extender” such as 3,3'-diaminodiphenyl sulfone or 3,3'-diaminobenzophenone to produce the siloxane-modified poly(amic acid). Thin films were cast from the reaction mixtures and subsequent thermal dehydration produced the poly(imide siloxane) block or segmented copolymers. Upper “cure” temperatures of 300°C were used to insure complete imidization. By varying the amount and molecular weight of the siloxane oligomer, a variety of novel copolymers of controlled composition have been synthesized. Tough, transparent, flexible soluble films were produced by this method. The thermal and bulk properties of films having low to moderate siloxane content closely resemble those of the unmodified polyimide controls. However, toughness and surface behavior can be enhanced.     

Synthesis and characterization of ethylene-xylene-based polysulfide block-copolymers using the interfacial polymerization method

Copolymers of linear and aromatic polysulfide blocks are synthesized using interfacial polymerization of dichloro-xylene-based aromatic and ethylene-dichloride-based non-aromatic organic monomers. Synthesized copolymers consist of poly(ethylene sulfide) as well as ploy (xylene sulfide) blocks. Fascinating properties of linear and aromatic polysulfide species are gathered in the structure of synthesized polysulfide copolymers. Ethylene dichloride and α,α′-dichloro-p-xylene are used as the non-aromatic and aromatic organic monomers, respectively. To investigate the influences of sulfur contents in the backbone of the polymer on the thermal stability of synthesized copolymers, poly(ethylene-xylene disulfide) (PEXDS), poly(ethylene-xylene trisulfide) (PEXTRS) and poly(ethylene-xylene tetrasulfide) (PEXTS) copolymers are synthesized using, respectively, sodium disulfide, sodium trisulfide and sodium tetrasulfide, as aqueous monomers. Compared to both linear and nonlinear homopolymers, synthesized copolymers exhibit improved thermal stability. Moreover, the thermal degradation temperatures of synthesized copolymers improve by decreasing the number of sulfur atoms in the backbone of copolymers. These results reveal that thermal degradation of polysulfide copolymers can be tailored by controlling the polysulfide chain’s sulfur contents. Structural characteristics of synthesized polysulfide copolymers are also investigated using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and X-ray diffraction analysis.     

Copolymers of long-side-chain di-n-alkyl itaconates or methyl n-alkyl itaconates with styrene: synthesis, characterization, and thermal properties

Two series of copolymers of styrene with di-n-alkyl itaconates or methyl n-alkyl itaconates with n-alkyl side chains of 12, 14, 16, 18, and 22, using different compositions in the feed have been prepared in bulk via radical at 60 °C with AIBN as initiator. In most of the cases the copolymers were obtained in goods yields, their composition being close to the feed composition and their physical states depending on the composition and the itaconate structure. The copolymers were characterized by FTIR and NMR spectroscopy. The ¹H NMR studies indicate that the copolymers have a mainly random distribution of the monomeric units. The thermal degradation process occurs in one step with decomposition temperatures intermediate between those of polyitaconate and polystyrene. Finally, the alkyl side chains of the itaconate moieties are able to crystallize in a paraffinic phase where the melting temperature and enthalpy increase as the itaconate content and the side chain length rise.     

Synthesis and characterization of poly(aryl ether sulfone)s with metallophthalocyanine pendant unit

A series of novel poly(aryl ether sulfone) copolymers containing dicyanophenyl group were prepared by the reaction of bis(4‐chlorophenyl)sulfone with (3,4‐dicyano) phenylhydroquinone and 4,4′‐isopropylidenediphenol. On this basis, a series of poly(aryl ether sulfone)s containing metallophthalocyanine units were synthesized by the reaction of poly(aryl ether sulfone)s containing dicyanophenyl group with excessive amounts of 1,2‐dicyanobenzene and the corresponding metal salt in quinoline. All these copolymers were found to have high glass transition temperature and thermal stability. These copolymers were found to be soluble in common solvents, and capable of forming transparent films by solution casting. The copolymers containing metallophthalocyanine units showed strong optical absorption in the visible region, and exhibited blue photoluminescence in solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3457–3461, 2006     

A thermal analysis study of bisphenol-A-polycarbonate–dimethylsiloxane block copolymers

The thermogravimetric analysis (TGA) of three block copolymers of poly(dimethylsiloxane)–Bisphenol-A-polycarbonate was measured in nitrogen and air from just above room temperature to 1000 K. Measurements were made on a Perkin-Elmer TGS-2 system equipped with a System 4 microprocessor controller. Weight loss curves were obtained for heating rates ranging from 1.5 (or lower) to 80°C/min. Results were analyzed according to the method of Flynn and Wall. Two degradation reactions were observed in air and in nitrogen, respectively. In air, the activation energy was found to be 28–35 kcal/mol. In the inert atmosphere, activation energies were 44±3 kcal/mol and 11–27 kcal/mol, respectively. No straightforward relationship was found between the thermal stability of the copolymers and their composition. The morphology of char residues formed at 80°C/min heating rate to 1000 K have been examined in relation to the Si content. The degree of char formation at different heating rates has been established in nitrogen and in air, respectively.     

Synthesis and characterization of novel poly(aryl ether ketone)s with metallophthalocyanine pendant unit from a new bisphenol containing dicyanophenyl side group

A new bisphenol, (3,4-dicyano)phenylhydroquinone was prepared via a three-step reaction. Then a series of novel poly(aryl ether ketone) copolymers containing dicyanophenyl groups were prepared by the reactions of 4,4′-difluorobenzophenone with (3,4-dicyano)phenylhydroquinone and 4,4′-isopropylidenediphenol. After that, a series of poly(aryl ether ketone)s with metallophthalocyanine pendants were synthesized via the reactions of poly(aryl ether ketone)s containing dicyanophenyl with excessive amounts of 1,2-dicyanobenzene and the corresponding metal salt in quinoline. These resulting copolymers were found to have high glass transition temperatures and high thermal stability. They have good solubility and are capable of forming tough films. These copolymers show strong optical absorption in the visible region and exhibit strong blue photoluminescence.     

Studies on inherently radiopaque acrylate copolymers for biomedical applications

Poly(glycidyl methacrylate-co-ethyl methacrylate) and poly(glycidyl methacrylate-co-butyl methacrylate) random copolymers (with 50–50 mol % of monomers) were made radiopaque by grafting iodine moieties through the ring opening reaction of the epoxy groups. The percentage weight of grafted iodine in the copolymers was found to be as high as 19%. The iodinated copolymers showed higher glass transition temperature and thermal stability in comparison with the parent copolymers. Iodinated copolymer of poly(glycidyl methacrylate-co-ethyl methacrylate) has improved glass transistion temperature than iodinated poly(glycidyl methacrylate-co-butyl methacrylate). Radiographic analysis of these iodinated copolymers showed excellent radiopacity. The in vitro cytotoxicity tests revealed cytocompatibility with cells. These radiopaque copolymers are expected to find application as dental and orthopedic cements. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal stability of conductive charge transfer complexes of poly(4-vinylpyridine)-poly(dimethylsiloxane) block copolymers

Summary Thermal stability of conductive charge transfer complexes of poly(4-vinylpyridine)-poly(dimethylsiloxane) (P4VP-PDMS) block copolymers with tetracyanoquinodimethane (TCNQ) was investigated by using thermal gravimetric analysis (TGA). The results show that both TCNQ simple and complex salts of polymers are thermally stable up to 800°C and depending on the amount of added neutral TCNQ, the residual product increased up to 75%.     

Thermal degradation of copolymers based on 2-substituted oxazolines and β-methylhydrogenitaconate

Summary The thermal stabilities of poly(-methylhydrogenitaconate-co-2-methyl-2-oxazoline) and poly(-methylhydrogenitaconate-co-2-ethyl-2-oxazoline) obtained by spontaneous copolymerization have been studied by programmed thermogravimetric analysis over the temperature range from 293 K to 773 K under a flow of nitrogen. Most of the copolymers do not show weight loss until 473 K and they degrade in one step. The kinetic parameters Ea, n and A were obtained following one method of thermogravimetric analysis. The reaction order for all copolymers was 1.0. The poly(-methylhydrogenitaconate-co-2-methyl-2-oxazoline)s were the most thermostable copolymers.     

Thermal behavior of ungrafted and grafted bagasse and wood pulps

The effect of grafting of methyl methacrylate (MMA) and acrylonitrile (AN) on the thermal behavior of the pulp of sugar cane loaded with CaCO₃ and the pulp of a broad-leaved tree has been studied by thermal methods. Different experimental conditions of grafting AN onto the eucalyptus pulp have been used, including both water and organic solvent systems as the medium of reaction. To optimize the grafting of MMA onto wood pulp, the effect of pulp swelling and the contact time of the monomer with the pulp have been examined. Ungrafted as well as grafted cellulose samples with different levels of grafting were characterized by differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA). The CaCO₃ filler makes the pulp of bagasse thermally more stable. The grafting of MMA onto the bagasse or the wood pulps improves their thermal stability. This is not the case for wood grafted with poly(AN). The thermal stability of the grafted and ungrafted samples varies after a few weight percent has been lost. The glass transition temperature (T_g) of the copolymers have been measured and they are in good agreement with the calculated data. © 1993 John Wiley & Sons, Inc.     

Polymers and copolymers based on vinyl tetrazoles, 1. Synthesis of poly(5-vinyl tetrazole) by polymer-analogous conversion of polyacrylonitrile

Interaction of polyacrylonitrile with sodium azide and ammonium chloride leading to the formation of poly(5-vinyl tetrazole) has been studied in detail. The reaction is found to proceed to high conversion extents (up to 94–94.5%) and allows to obtain polymeric products with a wide range of poly(5-vinyl-tetrazole) content. Comparative studies of the structures and properties of the obtained polymers and 5-vinyl tetrazole homopolymer as well as copolymers of 5-vinyl tetrazole with acrylonitrile have been carried out using IR, ¹³C NMR and complex thermal analysis data.     

Thermal energy storage by poly(styrene-co-p-stearoylstyrene) copolymers produced by the modification of polystyrene

A series of poly(styrene-co-p-stearoyl styrene) copolymers as novel polymeric solid–solid phase-change materials (SSPCMs) were synthesized by the modification of polystyrene with stearoyl chloride. The chemical structure and crystalline morphology of the synthesized copolymers were determined with Fourier transform infrared spectroscopy and polarized optical microscopy, respectively. The thermal energy storage properties and thermal stability of the SSPCMs were investigated with differential scanning calorimetry and thermogravimetric analysis, respectively. In addition, the thermal conductivity of the SSPCMs was measured with a thermal property analyzer. Moreover, thermal cycling tests showed that the copolymers had good thermal reliability and chemical stability after being subjected to 5000 heating/cooling cycles. The synthesized poly(styrene-co-stearoyl styrene) copolymers as novel SSPCMs have considerable potential for thermal energy storage and temperature-control applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Formation of cobalt nanoparticle dispersions in the presence of polysiloxane block copolymers

Stable suspensions of superparamagnetic cobalt nanoparticles have been prepared in poly(dimethysiloxane) (PDMS) carrier fluids in the presence of poly[dimethylsiloxane-b-(3-cyanopropyl)methylsiloxane-b-dimethylsiloxane] (PDMS-PCPMS-PDMS) triblock copolymers as steric stabilizers. A series of the polysiloxane triblock copolymers with systematically varied molecular weights were prepared via anionic polymerization using LiOH as an initiator. These copolymers formed micelles in toluene and served as ‘nanoreactors’ for thermal decomposition of the Co₂(CO)₈ precursor. The nitrile groups on the PCPMS central blocks are thought to adsorb onto the particle surface, while the PDMS endblocks protrude into the reaction medium to provide steric stability. The particle size can be controlled by adjusting the cobalt to copolymer ratio. TEM shows non-aggregated cobalt nanoparticles with narrow size distributions which are evenly surrounded with copolymer sheaths. However, some degree of surface oxidation was observed over time, resulting in a decrease in magnetic susceptibility.