Synthesis,polymerization, and thermal properties of a new acetylene-terminated schiff base

A new acetylene-terminated Schiff base monomer, N,N′-(1,4-phenylenedimethylidyne)-bis-(4-ethynylaniline) (PPP), was synthesized and was characterized by nuclear magnetic resonance and infrared spectroscopy. This monomer was then polymerized to yield a new polymer (PPPP) with alternating units of aromatic imine and diacetylene via an oxidative coupling polymerization of the acetylenic terminal groups. The monomer was also polymerized by thermal curing at elevated temperatures up to 400°C to afford a crosslinked polymer network without significant structural decomposition. Thermal properties and thermal reactions of the monomer and the polymers were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The polymers exhibit excellent thermal stabilities in an inert atmosphere. Electronic properties of the polymers are also discussed.     

Synthesis,characterization, and chiroptical property of optically active poly(urea-urethane)s

Five new optically active poly(urea-urethane)s were synthesized by solution polyaddition of (1S,2S)-(+)-2-amino-3-methoxy-1-phenyl-1-propanol ( 4 ) with diisocyanates (diphenylmethane-4,4′-diisocyanate, toluene-2,4-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, m-xylylene diisocyanate) at 80°C for 60 h. In some cases, the reaction mixture transformed into a gel when cooled to room temperature. The reduced viscosities are between 0.14 and 0.63 dL/g depending on the solvents and diisocyanates. Thermal behaviors of these polymers were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The T_g and crystallization temperature (T_c) were in the range of 80–200°C and 220–238°C, respectively. Thermal decomposition started at about 275°C, and the residual weights at 400°C were 15–60% depending on the polymers. The conformation of the polymers in film state was studied by circular dichroism (CD) spectra, by comparison with the corresponding model compounds which were synthesized from 4 and phenyl isocyanate or propyl isocyanate. Polymers derived from aromatic diisocyanates formed as ordered conformation in the film state, while those from aliphatic diisocyanates did not. After packing as chiral stationary phases of high-performance liquid chromatography (HPLC), the polymers showed selective resolution to trans-stilbene oxide and trans-1,2-cyclopentanedicarboxanilide. © 1993 John Wiley & Sons, Inc.     

Synthesis and properties of optically active aromatic polyimides derived from optically pure 1,1′-bi-2-naphthol

A series of new optically active aromatic polyimides containing axially dissymmetric 1,1′-binaphthalene-2,2-diyl units were prepared from optically pure (R)-(+)- or(S)-(−)-2,2′-bis(3,4-dicarboxyphenoxy)-1,1′-binaphthalene dianhydrides and various aromatic diamines via a conventional two-step procedure that included ring-opening polycondensation and chemical cyclodehydration. The optically pure isomer of dianhydride was prepared by a nucleophilic substitution of optically pure (R)-(+)- or(S)-(−)-1,1′-bi-2-naphthol with 4-nitrophthalonitrile in aprotic polar solvent and subsequent hydrolysis of the resultant tetranitrile derivatives, followed by the dehydration of the corresponding tetracarboxylic acids to obtain the dianhydrides. These polymers were readily soluble in common organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and m-cresol, etc., and have glass transition temperatures of 251–296°C, and 5% weight loss occurs not lower than 480°C. The specific rotations of the optically active polyimides ranged from +196° to +263°, and the optical stability and chiroptical properties of them were also studied. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3287–3297, 1997     

Wholly aromatic chiral polyamides bearing pendant phthalimido and L-isoleucine moities

<正>A potential biodegradable and optically active bulky chiral aromatic amide-imidic diacid monomer,(2S,3S)-5-(3- methyl-2-phthalimidylpentanoylarnino)isophthalic acid(7),containing a rigid phthalimide and flexible L-isoleucine pendant group was synthesized in three steps.New aromatic polyamides including pendant phthalimido groups and flexible side spacers have been synthesized by direct polycondensation reaction of equimolar amounts of different aromatic diamines with an optically active diacid 7,using N-methyl-2-pyrrolidone(NMP) as a solvent and triphenyl phosphite/CaCl_2/pyridine as a condensing agent.These polyamides were characterized by FTIR,~1H-NMR spectroscopy,specific rotation, thermogravimetric and elemental analysis.The resulting polymers have inherent viscosities in the range of 0.21-0.45 dL/g. Amino acid existence in this backbone results in optically active polymers.Due to introduction of bulky and flexible groups in these polyamides,they show improved solubility in polar aprotic solvents such as NMP and dimethylacetamide and also good thermal stability(10%weight loss temperatures in excess of 330℃,and char yields at 600℃in nitrogen higher than 62%).     

Fast synthesis of optically active polyamides containing <Emphasis Type="SmallCaps">l</Emphasis>-methionine linkages in ionic liquid via a microwave-assisted process

Several optically active aromatic polyamides have been synthesized via direct polycondensation of chiral diacid monomer 1 containing l-methionine moiety with diverse aromatic diamines 2a–2h in a green medium, namely 1,3-dipropylimidazolium bromide as a room temperature ionic liquid. In order to evaluate the advantages of microwave promotion of these polymerization reactions, we compared microwave irradiation (method I) with conventional oil bath heating (method II) by means of reaction rates, conversions, and inherent viscosities. The inherent viscosities of resulting polymers were ranging between 0.47–0.65 and 0.35–0.57 dL/g in methods I and II, respectively. These polymers were characterized by means of ¹H-NMR, FT-IR, elemental, organosolubility, differential scanning calorimetry, and thermal gravimetric analysis techniques. The obtained polymers show thermal stability up to 273 °C under nitrogen atmosphere and good solubility in polar organic solvents. Polymerization reactions proceeded in higher yields and moderate inherent viscosities under microwave irradiation conditions besides the dramatically shorter reaction times and achieving the more pure products.     

Thermal stability of the silica-aminopropylsilane-polyimide interface

Thermal degradation of the silica–aminopropylsilane–amic acid/imide interface was studied by modifying a high-surface-area, neutral silica gel with a number of substituted aminopropylsilanes (APS). These substrates were reacted further with phthalic anhydride or aromatic amic acid monomers and the thermal decomposition of the adsorbed/reacted materials was monitored by thermogravimetric analysis (TGA) and infrared (IR) spectroscopy. The 3-aminopropyltriethoxysilane/poly[N,N′-(p,p′-oxydiphenylene)pyromellitimide] interface was also evaluated by this method. Comparison clearly distinguishes the thermal decomposition of surface-bound APS from surface-bound alkylphthalimides, the adhesion product of alkylamines and aromatic amic acids. Alkylamine imidization with the elimination of aromatic amine (analogous to polymer scission) and the decomposition of the surface-bound imide are shown in the amic acid TGA profiles. This imidization and the accompanying aniline elimination begin at about 130°C, under nitrogen, to form the surface alkyl imide which slowly decomposes at 400°C. TGA analysis indicates that the surface-bound imide undergoes minimal degradation under nitrogen at 370 ± 10°C; temperatures above this threshold range produce changes in the APS–imide interface.     

Polycyclotrimerization of aromatic diynes: Synthesis,thermal stability,and light‐emitting properties of hyperbranched polyarylenes

New aromatic diyne monomers of 1,4‐diethynyl‐2,5‐(dihexyloxy)benzene ( 1 ), 1,6‐diethynyl‐2‐(hexyloxy)naphthalene ( 2 ), and 9,9‐bis(4‐ethynylphenyl)fluorene ( 3 ) are synthesized. Their homopolymerizations and copolymerizations with 1‐octyne ( 4 ) or phenylacetylene ( 5 ) are effected by TaBr₅–Ph₄Sn and CpCo(CO)₂–hν, giving soluble hyperbranched polyarylenes with high molecular weights (M_w up to ～ 2.9 × 10⁵) in high yields (up to 99%). The structures and properties of the polymers are characterized and evaluated by IR, NMR, UV, PL, and TGA analysis. The polymers show excellent thermal stability (T_d > 400 °C) and carbonize when pyrolyzed at 900 °C. Upon photoexcitation, the polymers emit deep blue light in the vicinity of ～400 nm with fluorescence quantum yields up to 92%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4249–4263, 2007     

Synthesis and characterization of optically active aromatic polyimides derived from 2,2′-bis(2-trifluoro- 4-aminophenoxy)-1,1′-binaphthyl and aromatic tetracarboxylic dianhydrides

Optically active 2,2′-bis(2-trifluoro-4-aminophenoxy)-1,1′-binaphthyl and its corresponding racemate were prepared by a nucleophilic substitution reaction of 1,1′-bi-2-naphthol with 2-chloro-5-nitrotrifluorotoluene and subsequently by the reduction of the resulting dinitro compounds. A series of optically active and optically inactive aromatic polyimides also were prepared therefrom. These polymers readily were soluble in common organic solvents such as pyridine, N,N′-dimethylacetamide, and m-cresol and had glass-transition temperatures of 256 ∼ 278 °C. The specific rotations of the chiral polymers ranged from 167 ∼ 258°, and their chiroptical properties also were studied. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4536–4540, 1999     

Optically active poly(amide–imide)s containing axially dissymmetric 1,1′-binaphthyl moieties

Novel optically active aromatic poly(amide–imide)s (PAIs) were prepared from newly synthesized 2,2′-bis(3,4-dicarboxybenzamido)-1,1′-binaphthyl dianhydride ((+ )-, (S)-, and (R)-BNDADA). PAIs based on dianhydride monomers with different ee % were investigated with respect to their structures and chiroptical properties. These polymers were highly soluble in polar aprotic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, pyridine, etc., and showed high glass transition temperatures of 287–290°C and 5% weight loss temperatures of 450–465°C in nitrogen. Optically active PAIs exhibited high specific rotations, excellent optical stabilities, and a dependence of optical activities on temperature. Investigations on chiroptical properties indicated that chiral conformation was possessed by optically active PAIs. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3147–3154, 1999     

Enantioseparation of doubly functionalized polar norbornenes by HPLC and their ruthenium‐catalyzed ring‐opening metathesis polymerization

Doubly fuctionalized polar norbornenes bearing the cyano and ester groups in 2,3‐positions are synthesized and enantiomers are separated by high performance liquid chromatography (HPLC) with a chiral stationary phase. These optically active monomers are polymerized by ruthenium carbene catalysts, and high yields of the polymers were obtained. The chiral monomer bearing ethyl ester gave an optically active polymer of lower, but opposite sign of optical rotation (monomer [α]_D = +61.0°, polymer [α]_D = ?3.1°). The circular dichroism (CD) of the obtained chiral polymers gave a Cotton effect. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 485–491, 2010     

Synthesis and chirooptical properties of optically active poly(ester imide)s based on axially asymmetric 1,1′‐binaphthyls

A series of optically active poly(ester imide)s (PEsI's) has been synthesized by the polycondensation reactions of new axially asymmetric dianhydrides, that is, (R)‐2,2′‐bis(3,4‐dicarboxybenzoyloxy)‐1,1′‐binaphthyl dianhydride and (S)‐2,2′‐bis(3,4‐dicarboxybenzoyloxy)‐1,1′‐binaphthyl dianhydride, and various diamines with aromatic, semiaromatic, and aliphatic structures. The polymers have inherent viscosities of 0.45–0.70 dL/g, very good solubility in common organic solvents, glass‐transition temperatures of 124–290 °C, and good thermal stability. Wide‐angle X‐ray crystallography of these polymers shows no crystal diffraction. In comparison with model compounds, an enhanced optical rotatory power has been observed for the repeat unit of optically active PEsI's based on aromatic diamines, and it has been attributed to a collaborative asymmetric perturbation of chiral 1,1′‐binaphthyls along the rigid backbones. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4318–4326, 2004     

Synthesis and Characterization of Novel Poly(Arylene Ether)s from 1,3‐bis(4‐Hydroxyphenyl) Benzene

Abstract

Several poly(aryl ether)s have been prepared by the condensation of 1,3‐bis(4‐hydroxy phenyl) benzene with different trifluoromethyl activated bis‐fluoro compounds. IR, ¹H and ¹³C NMR, and elemental analyses have established the resulting polymer structures. The properties of the polymers have been evaluated by DSC, TGA, dynamic mechanical analysis (DMA) and stress–strain analysis. The polymers 1a and 1c showed semi‐crystalline behavior as evident by sharp crystalline melting peaks at 299°C and 330°C along with glass transitions at 202°C and 216°C, respectively. The polymers showed very good thermal stability in air, high modulus, and high tensile strength with low elongation at break.     

Kinetic investigation on thermal decomposition of organophosphorous compounds

In this paper, the thermal behaviours of two organophosphorous compounds, N,N-dimethyl-N′,N′-diphenylphosphorodihydrazidic (NDD) and diphenyl amidophosphate (DPA), were studied by thermogravimetery (TG), differential thermal analysis (DTA) and differential scanning calorimetery (DSC) techniques under non-isothermal conditions. The results showed that NDD melts about 185 °C before it decomposes. NDD decomposition occurs in two continuous steps, in the 190–410 °C temperature range. First thermal degradation stage for NDD results a broad exothermic peak in the DTA curve that is continued with a small exothermic peak at the end of decomposition process. On the other hand, applying TG-DTA techniques indicates that DPA melts about 150 °C before it decomposes. This compound decomposes in the temperature range of 230 to 330 °C in two steps. These steps are endothermic and exothermic, respectively. Activation energy and pre-exponential factor for the first step of decomposition of each compound were found by means of Kissinger method and were verified by Ozawa–Flynn–Wall method. Activation energy obtained by Kissinger method for the first stage of NDD and DPA decompositions are 138 and 170 KJ mol⁻¹, respectively. Finally, the thermodynamic parameters (ΔG ^#, ΔH ^# and ΔS ^#) for first step decomposition of investigated organophosphorous were determined.     

Synthesis of novel polyaryl(ether–ketones) with tert-butyl pendent groups

Linear polyaryl(ether ketones) containing tert-butyl pendent groups were prepared from aromatic hydrocarbons and aromatic diacid chlorides, both classes of monomers containing tert-butyl pendent groups. The polymers were prepared in high yield and high molecular weight by low-temperature precipitation polycondensation in 1,2-dichloroethane. The presence of meta-oriented moieties and bulky pendent groups played a beneficial role with regard to solubility, while the thermal transitions and thermal resistance were not greatly impaired relative to conventional all para-oriented polyaryl(ether–ketones). The current polyaryl(ether–ketones) showed glass transition temperatures in the range 170–240°C and decomposition temperatures, as measured by TGA, of about 500°C. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1251–1256, 1998     

Synthesis and properties of aromatic polyamides with oligobenzamide pendent groups. I. Poly-5-(4-benzoylamino-1-benzoylamino)isophthalamides

A series of polyisophthalamides having pendent oligomeric benzamide groups were prepared by the Yamazaki reaction from common aromatic diamines and 5-(4-benzoylamino-1-benzoylamino)isophthalic acid. The latter was synthesized from 5-aminoisophthalic acid in a three-step synthesis by successive incorporation of benzamido groups. The new polymers were characterized by NMR, DSC, TGA, and WAXD and the properties were compared to those of corresponding unsubstituted polyisophthalamides. All of the polymers were essentially amorphous and their T_gs were about 20°C higher than the reference polymers. Initial thermal decomposition temperatures ranged from 375 to 420°C. All of the polymers were soluble in aprotic polar solvents without added salts. Properties of particular note were: the water uptake, which was particularly high, ranging from 7.5 to 18.2%, and the temporary insolubilization in concentrated sulfuric acid of films of the polymers heated for a short time to ≥ 200°C. © 1995 John Wiley & Sons, Inc.     

Synthesis of Poly(arylene ether amine)s from a Monomer Containing an Electron‐Donating Amine Group in a Nucleophilic Aromatic Substitution Reaction

Summary: Poly(arylene ether amine)s were synthesized by a nucleophilic aromatic substitution polycondensation of bis[4‐fluoro‐3‐(trifluoromethyl)phenyl]amine with several bisphenols. Even though the monomer has an electron‐donating diphenylamine moiety, which normally deactivates a nucleophilic aromatic substitution (S_NAr) reaction, the polymerization proceeded by a S_NAr reaction to give high‐molecular‐weight polymers. The polymers show good solubility in common organic solvents and have T_gs in the range of 123 °C to 177 °C.

High‐molecular‐weight poly(arylene ether amine)s synthesized by a S_NAr reaction with the monomer containing an electron‐donating diphenylamine moiety.     

Thermal behavior of drugs

Data on the thermal stability of drugs was required to obtain information for handling, storage, shelf life and usage. In this study, the thermal stability of two nonsteroidal anti-inflammatory drugs (NSAIDs) was determined by differential scanning calorimetry (DSC) and simultaneous thermogravimetery/differential thermal analysis (TG/DTA) techniques. The results of TG analysis revealed that the main thermal degradation for the naproxen and celecoxib occurs in the temperature ranges of 196–300 and 245–359 °C, respectively. The TG/DTA analysis of compounds indicates that naproxen melts (at about 158.1 °C) before it decomposes. However, the thermal decomposition of the celecoxib started about 185 °C after its melting. The influence of the heating rate (5, 10, 15, and 20 °C min⁻¹) on the DSC behavior of the both drug samples was verified. The results showed that, as the heating rate was increased, decomposition temperatures of the compounds were increased. Also, the kinetic parameters such as activation energy and frequency factor for the compounds were obtained from the DSC data by non-isothermal methods proposed by ASTM E696 and Ozawa. Based on the values of activation energy obtained by various methods, the following order for the thermal stability was noticed: naproxen > celecoxib. Finally, the values of ΔS ^#, ΔH ^#, and ΔG ^# of their decomposition reaction were calculated.     

Synthesis and Chiroptical Properties of Poly[N-(4-N′-(α-Methylbenzyl)-Aminocarbonylphenyl)-Mamaleimide]

Abstract

Radical homopolymerization of N-[4-N′-(α-methylbenzyl)-aminocarbonylphenyl]maleimide ((S)-MBCP) was carried out at 50 and 70°C for 24 h to give optically active polymers ([α]²⁵ _D = 159.8 to 163.4°). Radical copolymerizations of (S)-MBCP (M₁) were performed with styrene (ST, M₂, methyl methacrylate (MMA, M²) in THF at 50°C. The monomer reactivity ratios (r ₁, r ₂) and the Alfrey-Price Q, e values were determined as follows: r ₁ = 0.32, r ₂= 0.14, Q ₁ = 1.74, e ₁ = 0.96 in the (S)-MBCP-ST system; r ₁ = 0.54, r ₂ = 0.93, Q ₁ = 1.11, e ₁ = 1.23 in the (S)-MBCP-MMA system. Chiroptical properties of the polymers and the copolymers were also investigated, and asymmetric induction into the copolymer main chain is discussed.     

New thermally stable condensation polymers containing central ketal moieties derived from malonaldehydetetramethyl acetal and dihydroxyaromatic compounds

Abstract

A number of new condensation polymers with acetal units in the main chain and having linear and ladder-form structure and high thermal stability were synthesized by solution polycondensation of dihydroxyaromatic compounds with malonaldehydetetramethyl acetal as a reactive protected 1,3-dicarbonyl compound. Optimal conditions for polycondensation were obtained via study of the model compounds. In order to obtain high molecular weight polymers, general investigations on the influence of reaction conditions, such as monomer concentration and reaction temperature were carried out. All polymers were obtained in high yields and moderate inherent viscosity ranging from 0.25 to 0.41?dL/g. The proposed chemical structures of condensation polymers were confirmed by ¹H-NMR, ¹³C-NMR, FTIR spectroscopies, TGA, and DSC. Thermal analysis indicated that these polymers are stable up to 360?°C, and a 10% weight loss (T₁₀) were recorded on the TG curves in the temperature range of 381–411?°C in nitrogen atmosphere, indicating their good thermal stability.     

Structure of Styrene and Acrylate Block Copolymers

Abstract

Using UV light as the energy source and polystyrene- (PS-) or polymethyl methacrylate- (PMMA-) macroinitiators with active aromatic or aliphatic thiyl end groups, PS-PMMA and PMMA-PEA (poly-ethyl acrylate) block copolymers were synthesized. The molecular weights of both block copolymers increased with increasing reaction time. The reactivity of macroinitiators depended on the type of thiyl groups and monomer and not on the length of the polymer chain. The most reactive were macroinitiators containing resonance stabilized non-substituted or substituted aromatic end groups. The decomposition of the macroinitiators took place over the formation of the thiyl radical and macroradical. The bond length, the bond dissociation energy, and the bond order of macroradical end groups were calculated. The most reactive monomer was ethyl acrylate; the less reactive was styrene. The structure, the molecular weight, and the T _g of the styrene-acrylate block copolymers were determined. The PMMA/PEA block copolymer had two of block's T _g s, the first at 105°C, the second at ?24°C, and a third at 16°C which probably represents contacting segments.