Synthesis and characterization of polycarbonates by melt‐phase interchange reactions with alkylene and arylene diphenyl dicarbonates

Alkylene and arylene diphenyl dicarbonates were used as monomers for the preparation of polycarbonate polymers. The diphenyl dicarbonates were first prepared from dihydroxy compounds and phenyl chloroformate. The polycarbonates were then prepared by the melt‐phase polycondensation of these diphenyl dicarbonates with dihydroxy compounds as monomers. The same polycarbonates were also synthesized by a different route involving the polycondensation of a different arylene or alkylene diphenyl dicarbonates with bisphenol A diphenyl dicarbonate to give another series of polycarbonates. The process involved precondensation under a stream of nitrogen and then melt polycondensation at a high temperature and low pressure. The prepared polycarbonates were characterized by inherent viscosity measurement, Fourier transform infrared spectroscopy, ¹H‐NMR and ¹³C‐NMR spectroscopy, and powder X‐ray diffraction. The thermal properties of the polycarbonates were studied with differential scanning calorimetry and thermogravimetric analysis. With alkylene or arylene diphenyl dicarbonates as monomers, the polycondensation reactions led to the formation of polycarbonates with inherent viscosities of up to 0.68 dL/g and with high thermal stability. The glass‐transition temperature values of the polycarbonates were in the range 24–130°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3597–3609, 2006     

Synthesis and characterization of poly(ether carbonate)s by melt‐phase interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ether groups

A new method of synthesis of poly(ether carbonate)s based on interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ether group was presented. The diphenyl dicarbonate monomers were prepared from phenyl chloroformate and dihydroxy compounds containing ether group (e.g., diethylene glycol, bis(2‐hydroxyethyl ether) of bisphenol A, and 4,4′‐oxydiphenol). The process consisted of a precondensation step under a stream of dry argon followed by a melt polycondensation at 230 or at 250°C under vacuum. Four series of poly(ether carbonate)s were prepared using this approach. Using alkylene and arylene diphenyl dicarbonate‐containing ether groups as monomers, the polycondensation reaction with dihydroxy compounds led to the formation of poly(ether carbonate)s having inherent viscosity values up to 0.56 dL/g and high thermal stability. The glass transition temperature values of polycarbonates were in the range 7–122°C. The polymers were characterized by inherent viscosity and spectroscopic (Fourier transform infrared spectroscopy and ¹H‐NMR and ¹³C‐NMR) and thermal (differential scanning calorimeteric and thermogravimetric) methods. This approach may permit the use of diphenyl dicarbonates containing other organic functional groups for the synthesis of polycarbonates containing those groups. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and Thermal Properties of Polycarbonates Based on Bisphenol A by Single-phase Organic Solvent Polymerization

Linear alternating polycarbonates optionally containing bisphenol A were prepared from the reaction of linear aliphatic, substituted aliphatic, cyclic aliphatic and aromatic dihydroxy compounds with bisphenol A bischloroformate at 0–5 °C using a single organic phase as a reaction medium (e.g., Chloroform or tetrahydrofuran). Twelve aromatic–aromatic and aromatic–aliphatic polycarbonate polymers were prepared utilizing this procedure. The effect of the experimental conditions on the polymerization was studied and discussed. The polymers obtained were characterized by IR spectra, ¹H and ¹³C NMR spectra, inherent viscosity, differential scanning calorimetry, and thermogravimetric analyses.     

Viable utilization of polycarbonate as a phosgene equivalent illustrated by reactions with alkanedithiols,mercaptoethanol, aminoethanethiol,and aminoethanol: A solution for the issue of carbon resource conservation

Methods for the chemical recycling of polycarbonate (PC) wastes in the forms of bisphenol A (BPA) and cyclic heterocarbonates, such as 1,3‐dithiolan‐2‐one (DTO), 1,3‐dithiane‐2‐one (DTA), and cyclic unsymmetric heterocarbonates, were investigated to prove that PC can be utilized as a phosgene equivalent for industrial purposes. Treatment of PC pellets or waste PC compact discs with 1,2‐ethanedithiol and a catalytic amount of base (e.g., 1.5 mol % NaOH) in dioxane for a short period at 40°C produced DTO and BPA, both in nearly quantitative yields. The reaction could also be carried out in DTO, which saved the use of conventional solvents. Other cyclic heterocarbonates, that is, DTA, 1,3‐oxathiolan‐2‐one, 1,3‐thiazolidine‐2‐one, and N‐methyl‐1,3‐oxazolidine‐2‐one, were prepared in high yields under analogous conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2959–2968, 2003     

Small‐molecule‐induced miscibility of isosorbide‐based polycarbonate with bisphenol A polycarbonate

In this study, we investigated the influence of the small molecule 4,4′‐thiobis(6‐tert‐butyl‐m‐methyl phenol) (AO300) on the miscibility of poly(isosorbide‐co‐1,4‐cyclohexanedimethanol carbonate) (IcC–PC) with bisphenol A polycarbonate (BPA–PC) through the formation of hydrogen‐bonding networks. Differential scanning calorimetry and morphological observation revealed that the initially, immiscible BPA–PC/IcC–PC blends become miscible through the addition of small molecules. Fourier transform infrared spectroscopy confirmed that intermolecular hydrogen bonds formed between the hydroxyl groups of AO300 and the carbonyl groups of the studied polycarbonates. These polycarbonates exhibited different hydrogen‐bonding behaviors and various degrees of glass‐transition temperature composition dependence. Dynamic mechanical analysis demonstrated that AO300 played an antiplasticization role in the BPA–PC/IcC–PC blends with improved storage moduli. To our knowledge, this article is the first to describe the miscibility of isosorbide‐based polycarbonate with BPA–PC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44537.     

Physical properties of aliphatic polycarbonates made from CO2 and epoxides

A homologous series of aliphatic polycarbonates with different side‐chain lengths was synthesized by ring‐opening polymerization of terminal epoxides with CO₂ using zinc adipionate as catalyst [patented process of Empower Materials (formerly PAC Polymers Inc.)]. Additionally, a polycarbonate was made having a cyclohexane unit in its backbone, together with a terpolymer having both cyclohexane and propylene units. After characterization of thermal properties the aliphatic polycarbonates were found to be completely amorphous. Polycarbonates derived from long‐chain epoxides showed a glass‐transition temperature (T_g) below room temperature, whereas polycarbonates derived from cyclohexene oxide showed a T_g of 105°C, the highest yet reported for this class of polymers. The initial decomposition temperature of the polymers in air and nitrogen atmospheres was found to be less than 300°C. The mechanical properties and the dynamic mechanical relaxation behavior of the polymers were also reported. The effect of the chemical structure on the physical properties of aliphatic polycarbonates was discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1163–1176, 2003     

Halogen‐free solvent for oxidative carbonylation of bisphenol A to polycarbonate

Halogen‐free solvents for oxidative carbonylation of bisphenol A to polycarbonate using carbon monoxide were investigated. Tetrahydorofuran, γ‐butyrolacton, and acetophenone, which dissolve both bisphenol A and polycarbonate, gave a polycarbonate yield that was lower than using a halogenated solvent of dichloromethane. On the other hand, propylene carbonate that has a carbonate bond gave a polycarbonate yield the same as using dichloromethane. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Selective,Green Synthesis of Six‐Membered Cyclic Carbonates by Lipase‐Catalyzed Chemospecific Transesterification of Diols with Dimethyl Carbonate

A facile and green synthesis of six‐membered cyclic carbonates, the potential monomers for isocyanate‐free polyurethanes and polycarbonates, was achieved by transesterification of diols with dimethyl carbonate catalyzed by immobilized Candida antarctica lipase B, Novozym®435, followed by thermal cyclization in a solvent‐free medium. The difference in the chemospecificity of the lipase for the primary, secondary and tertiary alcohols as acyl acceptors was utilized to obtain a highly chemoselective synthesis of the cyclic carbonate in high yield. In the lipase‐catalyzed reaction with diols, the product contained almost equal proportions of mono‐ and di‐carbonates with 1,3‐propanediol having two primary alcohols, a higher proportion of mono‐carbonate with 1,3‐butanediol having a primary and a secondary alcohol, and mainly mono‐carbonate with 3‐methyl‐1,3‐butanediol having a primary and a tertiary alcohol. The chemospecificity of cyclic carbonates formed by thermal treatment at 90 °C was closely related to the proportion of mono‐carbonate. The yield of cyclic carbonate was 99.3% with 3‐methyl‐1,3‐butanediol, 85.5% with 1,3‐butanediol, and 43.2% with 1,3‐propanediol.     

Comparison of polycarbonate precursors synthesized from catalytic reactions of bisphenol‐A with diphenyl carbonate,dimethyl carbonate,or carbon monoxide

Transesterification of bisphenol‐A with diphenyl carbonate or dimethyl carbonate, and direct oxidative carbonylation of bisphenol‐A were compared to obtain polycarbonate precursors for phosgene‐free polycarbonate synthesis. The melt‐transesterification of bisphenol‐A and diphenyl carbonate occurred readily to produce reactive precursors without a significant equilibrium constraint. On the other hand, the transesterification of bisphenol‐A and dimethyl carbonate showed a serious equilibrium limitation in obtaining reactive polycarbonate precursors leading to high molecular weight polymers, and coproduced a significant amount of methylated bisphenol‐A. The direct oxidative carbonylation of bisphenol‐A with CO produced diphenolic‐ended oligomers and a significant amount of by‐products, which are the least reactive in the subsequent polycondensation step of the phosgene‐free polycarbonate process. A novel method to synthesize the reactive polycarbonate precursors was proposed that employed the coupled oxidative carbonylation of both bisphenol‐A and phenol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 937–947, 2002     

Synthesis,crosslinking, and abrasion and weathering properties of (meth)acrylate-terminated bisphenol A polycarbonates

(Meth)acrylate terminated bisphenol A polycarbonates [(M)AC PCs] were prepared under interfacial conditions by reaction of (meth)acryloyl chloride with bisphenol A (BA) followed by phosgenation. Addition of (M)ACl to an interfacial mixture of BA containing a catalytic amount of triethylamine followed by phosgenation gave linear polymers with good control of molecular weight. Thermal crosslinking of MAC PCs was generally achieved only in the presence of dicumyl peroxide. Between 75 and 98% gel was obtained by using 2 wt % initiator and heating for 30 min each at 150 and 200°C. All of the AC PCs crosslinked without added initiator to form 92–100% gel by heating for 30 min at 250°C. Coatings of high crosslink density (M)AC PCs on linear BA PC plaques were prepared by a combination of solvent casting, compression molding, and (optionally) oven curing. Moderate to high crosslink density (M)AC PC coatings showed relatively high pencil hardness values and good abrasion resistance. In weathering studies, both MAC and AC PC-coated plaques showed low YI increases, but the MAC PC coating developed higher haze due to microcracking. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 663–675, 1999     

Synthesis,molecular and optical characterization of polycarbonates containing azobenzene side‐chains

In this study, we report the synthesis and holographic characterization of polycarbonates containing an azobenzene group in their side‐chains. The polycarbonate (DR‐PC) was synthesized by the polyaddition reaction of Disperse Red 19 (DR 19) and carbon dioxide in N‐methyl‐2‐pyrrolidone for 24 h in air, and we investigated the mechanism in the presence of potassium carbonate. The film of polycarbonate was obtained by casting onto a slide glass in N,N‐dimethylformamide. The diffraction efficiency of the polycarbonate film was measured as a function of time and intensity of the induced laser. Independently of the intensity of the writing beam, the maximum diffraction efficiency in all DR‐PC films reached about 0.25%. Copyright © 2006 Society of Chemical Industry     

Open‐cell foams of polyethylene terephthalate/bisphenol a polycarbonate blend

Open microcellular foams of polyethylene terephthalate (PET)/polycarbonate (PC) blends were prepared by controlling their foaming behavior at the interface between these two polymers. Interface modification was a crucial factor in governing the foaming behavior and cell morphology of the blend foams: annealing at 280°C, i.e., conducting the transesterification reaction, generates a PET‐b‐PC copolymer, which lowers the interfacial tension, increases the affinity between PET and PC, and decreases the crystallinity of the PET domains. When CO₂ foaming was performed at the interface modified with the copolymer, an interesting fibril‐like structure was formed. The cell density of the PET/PC blend then increased, and its cell size reduced to the microscale while maintaining a high open‐cell ratio. The effect of heat annealing (transesterification reaction) on CO₂‐foaming was studied to reveal the relationship among the interface affinity, crystallinity, and degree of fibrillation. The optimal heat‐annealing procedure generated a fibril‐like structure in the PET/PC blend foams with a high cell density (7 × 10¹¹ cm^?3), small cell size (less than 2 μm), and 100% open‐cell ratio. POLYM. ENG. SCI., 55:375–385, 2015. © 2014 Society of Plastics Engineers     

Transesterifications of poly(bisphenol A carbonate) with aromatic and aliphatic segments in ethylene terephthalate–caprolactone copolyester

In this article, transesterification of poly(bisphenol A carbonate) (PC) with a ethylene terephthalate–caprolactone copolyester at a weight ratio 50/50 (TCL50) was investigated by infrared spectroscopy (IR), proton nuclear magnetic resonance spectroscopy (¹H‐NMR), and a model compound. The IR and ¹H‐NMR results showed that transesterification occurred between PC and ethylene terephthalate (ET) segments in TCL50 and resulted in the formation of bisphenol A–terephthalate ester units as in the annealed blend of PC with the PET homopolyester. By comparison with a model compound, the new signal at 2.55 ppm in the ¹H‐NMR spectrum confirmed the appearance of bisphenol A–caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. The ¹H‐NMR analysis of the transesterification rates revealed that the reactions of PC with aromatic and aliphatic segments in TCL50 proceeded in a random or free manner. In addition, we separately examined the interchange reaction between a PC and poly(ε‐caprolactone) (PCL) homopolyester in an annealed blend. It was found that in the presence of a Ti compound catalyst the predominant reaction was a transesterification rather than a thermooxidative branching reaction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1558–1565, 2001     

Reactive Alder‐ene blend of diallyl bisphenol A novolac and bisphenol A bismaleimide: synthesis,cure and adhesion studies

A novel, addition‐curable novolac resin (ABPF) was synthesized by the reaction of diallyl bisphenol A with formaldehyde using p‐toluene sulfonic acid as the catalyst. The synthesis conditions were optimized to obtain soluble polymer of desirable molecular weight distribution which was characterized by FT‐IR, NMR and SEC. ABPF was reactively blended with bisphenol A bismaleimide (BMIP) and cured through an Alder‐ene reaction at high temperatures. The cure characteristics of BMIP–ABPF blend with a maleimide:allyl phenol stoichiometry of 1:1 were studied using FT‐IR, DSC and DMA, which evidenced the multi‐step cure reactions taking place in the system. Cure optimization was evaluated by DSC, DMA and adhesive property tests. The moderately crosslinked blend was conducive for achieving the optimum adhesive properties on aluminium substrates. Retention of the adhesive properties was greater than 100% at 150 °C. © 2001 Society of Chemical Industry     

New thermosetting resin from bisphenol A‐based benzoxazine and bisoxazoline

Bisphenol A‐based benzoxazine was prepared from bisphenol A, formaline, and aniline. Curing reaction of bisphenol A‐based benzoxazine with bisoxazoline and the properties of the cured resin were investigated. Consequently, using triphenylphosphite as a catalyst, for the first time the ring‐opening reaction of benzoxazine ring occurred at 170°C, and then the phenolic hydroxyl group generated by the ring‐opening reaction of the benzoxazine ring reacted with the oxazoline ring at 200°C. The melt viscosity of the molding compound was kept 0.1–1 Pa · s at 140°C even after 1.5 h, and increased rapidly at 180°C. It was realized that the molding compound showed good flowability below 140°C, curing reaction proceeded above 180°C rapidly. The cured resin from bisphenol A‐based benzoxazine and bisoxazoline showed good heat resistance, water resistance, electrical insulation, and mechanical properties, compared with the cured resin from bisphenol A‐type novolac and bisoxazoline. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1551–1558, 1999     

Synthesis of biodegradable amphiphilic thermo‐responsive multiblock polycarbonate and its self‐aggregation behavior in aqueous solution

Amphiphilic thermo‐responsive multiblock polycarbonates consisting of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) were facilely synthesized using triphosgene as coupling agent. The structures and molecular characteristics of the polycarbonates were confirmed by ¹H‐NMR, FT‐IR and Gel permeation chromatography (GPC). The crystallization behavior and thermal properties of the polycarbonates were studied using X‐ray diffraction (XRD), Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Surface tension measurements confirmed that the critical micelles concentration of polymeric micelles were concentration ranges, which varied from about 2–70 mg/L to 5–40 mg/L with increasing PEO/PPO composition ratio from 0.8 to 1. Dynamic light scattering (DLS) experiments showed bimodal size distributions, the aggregates size increased with increasing the concentration of the polycarbonates aqueous solutions. The size of the aggregates acquired from TEM was smaller than that from DLS owing to the fact that TEM gave size of the aggregates in dry state rather than the hydrodynamic diameter. The degradation process revealed that the degradation rate of the aggregates could be accelerated with an increase in temperature. Moreover, the more the polycarbonate was hydrophilic, the faster was its degradation. Rheological measurements suggested that these multiblock polycarbonates were thermo‐responsive and by regulating the PEO/PPO composition ratio they could form a gel at 37°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Thermal degradation of bisphenol A polycarbonate by high-resolution thermogravimetry

Thermal degradation of bisphenol A polycarbonate (PC) has been studied in nitrogen and air from room temperature to 900 °C by high-resolution thermogravimetry (TG) with a variable heating rate in response to changes in the sample's degradation rate. A three-step (in nitrogen) or four-step (in air) degradation process of the PC, which was hardly ever revealed by traditional TG, has been found. The initial thermal degradation temperature of the PC is higher in nitrogen than in air, but the three kinetic parameters (activation energy E, decomposition order n, frequency factor Z) of the major degradation process are slightly lower in nitrogen. The average E, n and lnZ values determined by three methods in nitrogen are 154 KJ mol⁻¹, 0.8 and 21 min⁻¹, respectively, which are almost the same as those calculated by traditional TG measurements. © 1999 Society of Chemical Industry     

A preliminary study of blends of bisphenol a polycarbonate and poly(ethylene terephthalate)

The microstructure of blends of bisphenol A polycarbonate (PC), and poly(ethylene terepthalate) (PETP) has been studied by solvent extraction, infrared spectrophotometry, differential scanning calorimetry and dynamic mechanical thermal analysis. The blends appear to contain two amorphous phases over the whole composition range. The tensile behaviour and the Charpy impact strength of some of the blends have been determined, before and after heat treatment at 125°C for 18 hours. Improved performance of the blends, compared with that of the homopolymers PC and PETP, has been demonstrated.     

Structure and properties of ultra‐high molecular weight bisphenol a polycarbonate synthesized by solid‐state polymerization in amorphous microlayers

The structure and properties of ultrahigh molecular weight polycarbonate synthesized by solid‐state polymerization in micro‐layers (SSP_m) are reported. A low molecular weight prepolymer derived from the melt transesterification of bisphenol A and diphenyl carbonate as a starting material was polymerized to highly amorphous and transparent polycarbonate of molecular weight larger than 300,000 g mol^?1 in the micro‐layers of thickness from 50 nm to 20 µm. It was observed that when the polymerization time in micro‐layers was extended beyond conventional reaction time, insoluble polymer fraction increased up to 95%. Through the analysis of both soluble and insoluble polymer fractions of the high molecular weight polycarbonate by ¹H NMR spectroscopy and pyrolysis‐gas chromatography mass spectrometry (Py‐GC/MS), branches and partially crosslinked structures have been identified. The thermal, mechanical and rheological properties of the ultra‐high molecular weight nonlinear polycarbonates synthesized in this study have been measured by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and rheometry. The nonlinear chain structures of the polymer have been found to affect the polymer's thermal stability, mechanical strength, shear thinning effect, and elastic properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41609.     

Blends of poly(hydroxyether of bisphenol A) and polycarbonate: in situ polymerization preparation,miscibility, and transreaction

In the presence of polycarbonate (PC), the polymerization of diglycidyl ether of bisphenol A (DGEBA) and bisphenol A in the melt was initiated to prepare blends of poly(hydroxyether of bisphenol A) (phenoxy) and PC. The polymerization reaction started from the initially homogeneous ternary mixture consisting of DGEBA, bisphenol A, and PC; phenoxy/PC blends with PC content up to 20 wt % were obtained. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were employed to characterize the miscibility of the as-polymerized blends. All the blends displayed separate glass transition temperatures (T_g's), that is, the blends were phase-separated. The formation of a two-phase structure is considered to result from phase separation induced by polymerization. This result is consistent with the immiscibility established through solution- and melt-blending approaches. The insolubility of the as-polymerized blends showed that crosslinking between the components occurred. Both Fourier-transform infrared (FTIR) and solid ¹³C-nuclear magnetic resonance (¹³C-NMR) spectroscopic studies demonstrated a transreaction between the components and in situ polymerization of DGEBA and bisphenol A in the presence of PC, which yielded a phase-separated, transreacted material. The results of this work provide a contrast to those of the transreacted phenoxy/PC blends based on conventional blending methods; however, the transreaction in the present case occurred at a much lower temperature (180^oC), at which polymerization blending was carried out. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1181–1190, 1999