Functional Polymers. X. Hydrolysis Studies of Polyesters and Polycarbonates of Bithionol and Their Copolymers

The hydrolysis behavior of a number of polymers of bithionol [2,2′-thiobis(4,6-dichlorphenol)] was investigated. The hydrolysis of polyesters of bithionol with aliphatic or aromatic dicarboxylic acids or phosphorus acids as well as polycarbonates and alternating copolycarbonates and polyurethanes or co(po1y-carbonates/polyurethanes) depends primarily on the water solubility of the polymer or at least on its degree of swelling. In the most favorable case of the alternating bithionol/PEG 4000 co-polycarbonate the hydrolysis rate of the polymer at 37°C was 1.62 L/mol/min at pH 10, 0.63 L/mol/min at pH 4 and 0.17 L/mol/min at pH 7.4. Copolycarbonates and copolyurethanes with PEG 4000 in the polymer chain have slightly lower rates of hydrolysis. When the solubility of the polymer is low and the crystallinity     

Synthesis and properties of polyurethanes derived from bis-N-hydroxyimides and diisocyanates

Polyurethanes were synthesized by polyaddition reaction of bis-N-hydroxyimides and diisocyanates. The reactions were carried out in an aprotic polar solvent such as dimethylacetamide or N-methyl-2-pyrrolidone, and the polymers with inherent viscosities of up to 1.32 dl/g were obtained. These polyurethanes were found to exhibit high reactivity toward nucleophiles such as water and amines, which brought about rapid reduction of viscosity. The stabilities against heat and exposure to sunlight were also studied.     

Poly(arylene sulfides) with pendant cyano groups as high-temperature laminating resins. II

Poly(phenylene sulfides) containing various amounts of pendant cyano groups were synthesized from m-benzenedithiol and the corresponding amounts of p-dibromobenzene and 3,5-dichlorobenzonitrile. The polymers prepared by the use of 10, 15, 20, and 25% of the nitrile-containing dichloro compound were slightly off-white with melting ranges below 100°C and had inherent viscosities of about 0.15 dl/g in hexamethylphosphoric triamide at 30°C. The polymers prepared from m-benzenedithiol and the stoichiometric amounts of 2,4-dichlorobenzonitrile or 3,5-dichlorobenzonitrile looked similar to those described above, yet they possessed much higher melting ranges. The poly(phenylene sulfide) prepared by the use of 2,4-dichlorobenzonitrile had an inherent viscosity of 0.06 dl/g while the polymer prepared from the 3,5-dichloro isomer had an inherent viscosity of 0.38 dl/g. All the polymers listed above were crosslinked by heating alone or in the presence of anthracene-9,10-bisnitrile oxide to give black resinous polymers that were insoluble in hexamethylphosphoric triamide in which the original polymers dissolved quite readily.     

Polyimidines. VI. The comparison of polyimidines from bis(3,3-diphenyl-6-phthalidyl) ketone

New thermally stable polyimidines have been synthesized from bis(3,3-diphenyl-6-phthalidyl) ketone and five diamines: o-phenylenediamine, m-phenylenediamine, 1,5-diaminonapthalene, 1,8-diaminonapthalene, and benzidine. Polymers of low molecular weight (inherent viscosity up to 0.24 dl/g) were obtained by solution and sealed-tube polymerizations. The structural differences of the amines provided information concerning the effects on the thermal stability properties of the resulting polyimidines. The yellow to black polymers exhibited a 10% loss ranging from 420–510°C in air and 460–555°C in nitrogen and were soluble in chloroform and dimethylformamide.     

Polymers of carbonic acid. XXIV. Photoreactive,nematic or cholesteric polycarbonates derived from hydroquinone-4-hydroxybenzoate 4,4′-dihydroxychalcone and isosorbide

Numerous polycarbonates were prepared by means of “diphosgene” in pyridine using hydroquinone 4-hydroxybenzoate (HQHB) as mesogenic diphenol. In addition to the homopolycarbonate, binary copolycarbonates of HQHB and 4,4′-dihydroxychalcone (DHC) with varying molar composition were prepared. A series of ternary copolycarbonates were obtained by incorporation of isosorbide. Furthermore, an alternating copolycarbonate of HQHB and isosorbide was synthesized. All polycarbonates were characterized by inherent viscosities, elemental analyses, IR-, ¹H-NMR, and ¹³C NMR spectroscopy, by WAXS powder patterns DSC measurements, and optical microscopy with crossed polarizers. The homopolycarbonate of HQHB and most binary copolycarbonates were semicrystalline materials forming an enantiotropic nematic melt. Particularly noteworthy is the finding that the alternating copolycarbonate of HQHB and isosorbide forms a broad cholesteric phase despite the unfavorable stereochemistry of isosorbide. The ternary copolycarbonates containing isosorbide formed a cholesteric melt and a Grandjean texture upon shearing. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1611–1619, 1997     

Thermotropic liquid crystalline polymers with low thermal transitions. I. Low melting thermotropic liquid crystalline homo- and co-polycarbonates

Due to the particular rheological properties of thermotropic liquid crystalline polymers (TLCP), their application for imaging technology has been investigated. The first class of polymers investigated in this study are the thermotropic liquid crystalline polycarbonates prepared from the solution polycondensation of p,p-dihydroxybiphenyl with bischloroformate as the aliphatic flexible spacer. From the variety of bischloroformates employed, smectic TLCP's were generally obtained with the possible presence of a nematic mesostate. The introduction of comonomers such as substituted hydroquinones or bisphenols were found to lower both the melting transitions and mesophasic range of the TLCP. From rheological characterization, the amount of nonmesogenic moieties present in the copolycarbonates were found to correlate with the increase in the melt viscosity of TLCP.     

Flame retardation of polyurethanes by means of 1,4-bis[(dialkoxyphosphinyl)hydroxymethyl]benzene

New phosphorus-containing homopolyurethanes were synthesized by reacting various diisocyanates such as tolylene diisocyanate, methylenebis(4-phenylisocyanate) and hexamethylene-1,6-diisocyanate with 1,4-bis[(dialkoxyphosphinyl)hydroxymethyl]benzene (BDAB). In addition, copolyurethanes containing approximately 3% phosphorus were prepared by copolymerization of these diisocyanates with an equimolar amount of BDAB—hydroquinone mixture. BDAB was less reactive towards diisocyanates than hydroquinone due to the electron-withdrawing inductive effect of the phosphinyl groups. The polymers synthesized were characterized by inherent viscosity measurements as well as by proton nuclear magnetic resonance (¹H-NMR) and infrared (IR) spectroscopy. The spectroscopic examination of polymers did not provide evidence for crosslinking by allophanate groups. Differential thermal analysis (DTA) studies of polymers revealed that the incorporation of BDAB in polyurethanes altered their thermal decomposition mode by increasing the exothermicity due to pyrolysis. Thermogravimetric analysis (TGA) of polymers showed that the phosphorus-containing homopolyurethanes and copolyurethanes were thermally less stable than the corresponding common polyurethanes but afforded higher char yields. Determination of the limiting oxygen index (LOI) values showed that the phosphorus-containing copolyurethanes exhibited a higher fire resistance than that of common polyurethanes.     

Biodegradable polymers based on renewable resources. VII. Novel random and alternating copolycarbonates from 1,4:3,6‐dianhydrohexitols and aliphatic diols

Novel copolycarbonates containing 1,4:3,6‐dianhydro‐D ‐glucitol or 1,4:3,6‐dianhydro‐D ‐mannitol units, with various methylene chain lengths, were synthesized by bulk and solution polycondensations, of several combinations of carbonate‐modified sugar derivatives and aliphatic diols. Bulk polycondensations of 1,4:3,6‐dianhydro‐2,5‐bis‐O‐(phenoxycarbonyl)‐D ‐glucitol or 1,4:3,6‐dianhydro‐2,5‐bis‐O‐(phenoxycarbonyl)‐D ‐mannitol with four α,ω‐alkanediols having methylene chain lengths of 4, 6, 8, and 10, respectively, at 180 °C afforded the corresponding copolycarbonates with number‐average molecular weight (M_n) values up to 19.₂ × 10³. ¹³C NMR analysis disclosed that these polymers had scrambled structures in which the sugar carbonate and aliphatic carbonate moieties were nearly randomly distributed along a polymer chain. However, solution polycondensations between 1,4:3,6‐dianhydro‐2,5‐bis‐O‐(p‐nitrophenoxycarbonyl)‐D ‐glucitol or 1,4:3,6‐dianhydro‐2,5‐bis‐O‐(p‐nitrophenoxycarbonyl)‐D ‐mannitol, and the α,ω‐alkanediols in sulfolane or dimethyl sulfoxide at 60 °C gave well‐defined copolycarbonates having regular structures consisting of alternating sugar carbonate and aliphatic carbonate moieties with M_n values up to 33.₈ × 10³. Differential scanning calorimetry demonstrated that all the copolycarbonates were amorphous with glass‐transition temperatures ranging from 1 to 65 °C, which decreased with increasing lengths of the methylene chain of the aliphatic diols. Additionally, all the copolycarbonates were stable up to 310–330 °C as estimated by thermogravimetric analysis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2312–2321, 2003     

Polyimides derived from bis-N-hydroxyimides. II. Synthesis and properties of polyimide-esters

Polycondensation of bis-N-hydroxyimides, N,N′ dihydroxypyromellitic diimide, and N,N′ -dihydroxybenzophenonetetracarboxylic diimide with dicarboxylic acid chlorides was carried out in dimethylacetamide in the presence of triethylamine to produce novel polyimide-esters. The resulting polymers had inherent viscosities up to 0.27 dl/g. These polyimide-esters and model compounds exhibited high reactivity toward nucleophiles such as aniline and n-butylamine, which brought about rapid reductions in the viscosity of the polymers. These polymers were fairly resistant to organic solvents but soluble in m-cresol. Thermal stability oft he polyimide-esters was evaluated by thermogravimetry and their good heat-resistant properties were confirmed.     

Novel processable aromatic thermoplastic polyimides: Films,adhesives, moldings,and graphite composites

Novel hot-melt type flexible, tough, thermally stable, processable, thermoplastic, aromatic polyimides have been synthesized involving reaction of a keto-ether containing diamine with hinged aromatic dianhydrides followed by thermal and chemical cyclodehydration. Inherent viscosity in DMAC at 35°C of the synthesized polymers ranged 1.02 to 1.4 dl/g (0.5% solution). The polymers showed a glass transition temperature (T_g) of 250°C to 180°C as determined by differential scanning calorimetry (DSC) and thermomechanical analysis (TMA). Thermogravimetric analysis showed polymer stability up to 510°C, in both air and nitrogen atmospheres. All the polymers have shown good melt-flow. Films of 1.5–2.8 ml thickness were made and tested for mechanical properties at room temperature, 177°C and 210°C. The developed films are suitable for adhesion of Ti/Ti specimens and showed a lap shear strength of 5575 psi. Melt-fusion of the polymers gave tough moldings. Graphite cloth composites have been made and tested for mechanical properties.     

Hyperbranched polyurethanes with varying spacer segments between the branching points

Hyperbranched polyurethanes, with varying oligoethyleneoxy spacer segments between the branching points, have been synthesized by a one-pot approach starting from the appropriately designed carbonyl azide that incorporates the different spacer segments. The structures of monomers and polymers were confirmed by IR and ¹H-NMR spectroscopy. The solution viscosity of the polymers suggested that they were of reasonably high molecular weight. Reversal of terminal functional groups was achieved by preparing the appropriate monohydroxy dicarbonyl azide monomer. The large number of terminal isocyanate groups at the chain ends of such hyperbranched macromolecules caused them to crosslink prior to its isolation. However, carrying out the polymerization in the presence of 1 equiv of a capping agent, such as an alcohol, resulted in soluble polymers with carbamate chain ends. Using a biphenyl-containing alcohol as a capping agent, we have also prepared novel hyperbranched polyurethanes with pendant mesogenic segments. These mesogen-containing polyurethanes, however, did not exhibit liquid crystallinity probably due to the wholly aromatic rigid polymer backbone. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of polycarbonates based on bisphenol S by melt transesterification

Several sulfone-containing polycarbonates, having inherent viscosity 0.25–0.30 dL g⁻¹ in N,N-dimethylformamide (DMF), were prepared by melt polycondensation of diphenyl carbonate (DPC) with various aromatic and aliphatic diols, in the presence of zinc acetate as transesterification catalyst. The polycarbonates were examined with IR spectra, inherent viscosity, solubility, tensile strength, contact angle, DSC and TGA. Almost all polymers were soluble in DMF, pyridine, N-methyl pyrrolidinone (NMP), THF, phenol and dimethylsulfoxide (DMSO), partially soluble in nitrobenzene, but insoluble in acetone. Polycarbonate with introduced ether linkages leads to enhanced flexibility and elongation strength. The contact angle of the polycarbonate based on bisphenol S was found in the range 42–80°, smaller than that of polycarbonates based on bisphenol AF and bisphenol A. The wettability of polycarbonate films based on bisphenol S remarkably increased with increasing oxyethylene unit in polymer chain. The smaller values of T_d of PC-3-PC-7 than of PC-1 is attributed to the flexible ether linkage. The thermal stability of a brominated aromatic polycarbonate (PC-2) is less than that of the unbrominated one (PC-1). The brominated aromatic polycarbonate (PC-2) has good flame retardency, as indicated by the large limiting oxygen index 56. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2453–2460, 1997     

Electron-transfer polymers. XXXIV. Redox polyurethanes from p-benzoquinone-2,5-diols and diisocyanates

It is possible to prepare polyurethanes from p-benzoquinone-diols and diisocyanates by using dibutyltin diacetate catalyst at room temperature or below, since the benzoquinone group does not react with isocyanate under these conditions. This permits preparation of new redox polymers. In preparing the polyurethanes excess isocyanate groups must be destroyed at the end of the reaction time in order to prevent crosslinking during work-up. These polymers are readily reduced by aqueous hydrosulfite. Good viscosity numbers are obtained; and, in general, upon reduction the viscosity increases over that of the oxidized form. There is no evidence of crosslinking. When oxidized and reduced forms of these polymers are mixed there is no evidence of charge transfer.     

Polyimides derived from bismethylolimides. I. Polyamide–imides from bismethylolimides and dinitriles

New polyamide–imides were synthesized from bismethylolimides and dinitriles. The bismethylolimides, N,N′-bismethylolpyromellitdiimide and N,N′-bismethylolbenzophenonete-tracarboxylic diimide, were prepared by the hydroxymethylation of the corresponding diimides with formaldehyde. The polymerization reaction was carried out in either concentrated sulfuric acid or poly(phosphoric acid), and the former was found to be superior to the latter. The polyamide–imides had inherent viscosities in the 0.08–0.41 dl/g range. Most of these polymers were soluble in m-cresol and dichloroacetic acid. The thermal stability of the polymers was examined by thermogravimetric analysis, and they were found to start to decompose at 275–350°C in air.     

Stereoregular poly‐O‐methyl [m,n]‐polyurethanes derived from D‐mannitol

Novel linear carbohydrate‐derived [m,n]‐polyurethanes are successfully prepared using D ‐mannitol as renewable and low cost starting material. The key comonomer, 1,6‐di‐O‐phenylcarbonyl‐2,3,4,5‐tetra‐O‐methyl‐D ‐mannitol is polymerized with a diamine synthesized from D ‐mannitol or with alkylenediamines. These polymerization reactions afford, respectively, a [6,6]‐polyurethane entirely based on a carbohydrate derivative or [m,n]‐polyurethanes constituted by a poly‐O‐methyl substituted unit alternating with a polymethylene chain. All these polymers are stereoregular, as result of the C₂ axis of symmetry of mannitol. The optically active polyurethanes are characterized by standard methods (FTIR, RMN, GPC, TGA, and DSC). Thus, GPC analysis reveals weight‐average molecular weights between 18,000 and 25,000 Da. Thermal studies (DSC) indicate that the polymers obtained are amorphous materials with T_g values dependent on the structure and chain length of the diamine constituent. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Bulk polymerization of p‐dioxanone using a cyclic tin alkoxide as initiator

Poly(p‐dioxanone) with an inherent viscosity of over 1 dL/g has been synthesized using the cyclic tin alkoxide 1‐di‐n‐butyl‐1‐stanna‐2,5‐dioxacyclopentane as initiator. Poly(p‐dioxanone) was synthesized in bulk and the results have been compared with polymerizations using tin (II) 2‐ethylhexanoate (Sn(Oct)₂) as catalyst. Sn(Oct)₂ has often been reported to be an effective catalyst for the synthesis of poly(p‐dioxanone), but here it is compared with an initiator which is less prone to catalyze transesterification reactions. The results demonstrate that the cyclic tin initiator is a promising alternative for the synthesis of poly(p‐dioxanone) with a high inherent viscosity. Poly(p‐dioxanone) is a polymer with mechanical properties and a degradation rate suitable for tissue engineering applications. Both the cyclic tin initiator and Sn(Oct)₂ gave, under some reaction conditions, inherent viscosities around 1 dL/g. The best polymer synthesized using the cyclic tin initiator had a strain‐at‐break of 515% and a stress‐at‐break of 43 MPa. The inherent viscosity of this polymer was 1.16 dL/g, while Sn(Oct)₂ resulted in a polymer with an inherent viscosity less than 0.4 dL/g under the same reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5552–5558, 2007     

Polymers with improved flammability characteristics. II. Phenolphthalein related copolycarbonates

Analysis of phenolphthalein and bisphenol-A copolycarbonates reveals a linear correlation between oxygen index (OI) and char yield (Y): OI = 0.34Y + 19.6, which can be compared with the empirical equation QI = 0.4Y + 17.5 proposed by D. W. Van Krevelen for other polymers. Analysis also suggests that no chemical interction occurs between the two comonomers during pyrolysis, which leads neither to enhanced char yield nor to enhanced oxygen index. Each copolymer component contributes to the char yield and oxygen index on an additive basis. Study of 4,5,6,7-tetrabromophenolphthalein and phenolphthalein copolycarbonates shows that some enhancement of char yield does occur and that the lower the char yield, the higher the oxygen index, which is an indication of the predominance of a vapor-phase bromine effect over that related to char. Study of 4,5,6,7-tetrabromophenolphthalein and bis-phenol-A copolycarbonates is interpreted on the basis of two factors—the char effect that prevails over the vapor phase radical scavenging effect at lower bromine content and the reverse order at higher bromine content.     

Polymerization by Phase-Transfer Catalysis. Part 20. Synthesis of Polycarbonates and Polythiocarbonates with an Ester Group in the Side Chain

Abstract

Poly(ester-carbonate)s and poly(ester-thiocarbonate)s were synthesized from diphenols containing an ester group in the side chain and phosgene or thiophosgene under phase-transfer conditions. The polymers were characterized by elemental analysis and IR spectroscopy, and the molecular weights were estimated by inherent viscosity measurements. The influence of the nature of the catalysts and the structure of the diphenols on the yields and inherent viscosities was studied. We found that the catalysts were effective for all monomers, although the inherent viscosity values were low due to the insolubility of the polymers in the reaction media. Without catalyst, the polymers were not obtained.     

Synthesis,characterization, and properties of novel poly(ether urethanes)

Novel poly(ether urethanes) were synthesized by homo- and random copolymerization of the m- and p-hydroxyethoxy benzoyl azides. Polymerization proceeded by decomposition and rearrangement of the acid azide group to the isocyanate group, which immediately reacted intermolecularly with the hydroxyl group to produce polyurethanes. These polymers were characterized by infrared spectroscopy (IR), nuclear magnetic resonance spectroscopy (NMR), x-ray diffraction, scanning electron microscopy (SEM), viscosity, and solubility. The thermal stability of these polymers was also studied by TG and DTG (derivative TG).     

Effect of molecular structure on mesomorphism XXI. Monodisperse tetrameric model compounds for liquid crystalline polymers

Abstract

Twinned dimeric mesogens having a rigid-flexible-rigid molecular structure have been shown to be appropriate models for some properties of regularly alternating (rigid-flexible)_n main chain liquid crystalline polymers (lcps). A family of tetrameric monodisperse liquid crystalline model compounds chemically related to known main chain liquid crystalline polymers of the 4-alkoxyphenyl 4′-alkoxy-benzoate type has been synthesized. The tetramers are nematogenic. Alternations in thermodynamic parameters (ΔH, ΔS) for the N-I transition as a function of spacer chain length indicate conformational behaviour of the internal spacers dominates mesophase properties.