Recycling of End-of-Life Poly(bisphenol A carbonate) via Alkali Metal Halide-Catalyzed Phenolysis

The chemical recycling of end-of-life plastic waste streams can contribute to a resource-conserving and sustainable society. This matter of recycling is composed of a sequence of depolymerization and subsequent polymerization reactions. In this regard, we have studied the chemical recycling of end-of-life poly(bisphenol A carbonate) applying phenol as depolymerization reagent. In the presence of catalytic amounts of alkali metal halides as products bisphenol A and diphenyl carbonate were obtained in excellent turnover frequencies of up to 1392 h⁻¹ and short reaction times. These depolymerization products offer the straightforward possibility to close the cycle by producing new poly(bisphenol A carbonate) and as second product phenol, which can be reused for further depolymerizations.     

Hydrogenative Depolymerization of End-of-Life Polycarbonates by an Iron Pincer Complex

Chemical recycling processes can contribute to a resource-efficient plastic economy. Herein, a procedure for the iron-catalyzed hydrogenation of the carbonate function of end-of-life polycarbonates under simultaneous depolymerization is presented. The use of a straightforward iron pincer complex leads to high rate of depolymerization of poly(bisphenol A carbonate) and poly(propylene carbonate) yielding the monomers bisphenol A and 1,2-propanediol, respectively, as products under mild reaction conditions. Furthermore, the iron complex was able to depolymerize polycarbonates containing goods and mixture of plastics containing polycarbonates.     

不同链结构的双酚A聚碳酸酯对脂肪族聚碳酸酯结晶行为的影响

脂肪族聚碳酸酯(APC)是一类可降解的高分子材料,因其生产工艺可固定温室气体的主要成分二氧化碳,这种可降解塑料得到了越来越多的关注.作为半结晶高分子材料,脂肪族聚碳酸酯的结晶性能和结晶结构对成型加工、力学性能和降解性能具有重要的影响.借助热分析(示差扫描量热仪DSC)和形态学观察(偏光显微镜POM)两种方法研究了不同链结构的双酚A型聚碳酸酯对半结晶脂肪族聚碳酸酯——聚碳酸1,4-丁二醇酯结晶动力学行为的影响.实验发现质量分数1%的双酚A聚碳酸酯的加入促进了聚碳酸1,4-丁二醇酯的成核,但不同链结构的双酚A聚碳酸酯对其晶体生长具有相反的作用,线形双酚A聚碳酸酯(PC-L)能够促进晶体生长,而支化双酚A聚碳酸酯(PC-B)则抑制晶体生长.用原子力显微镜在轻敲模式下研究了两种双酚A聚碳酸酯与APC共混物熔融状态下的相结构,发现熔体结构的不同是导致两种共混物与纯的APC相比,结晶速率呈现相反变化趋势的主要原因.     

Towards early detection of the hydrolytic degradation of poly(bisphenol A)carbonate by hyphenated liquid chromatography and comprehensive two-dimensional liquid chromatography

The hydrolytic degradation of poly(bisphenol A)carbonate (PC) has been characterized by various liquid chromatography techniques. Size exclusion chromatography (SEC) showed a significant decrease in molecular mass as a result of hydrolytic degradation, while ‘liquid chromatography at critical conditions’ (LC-CC) was very successful for observing differences in functionality due to degradation, i.e. the formation of OH end-groups. To characterize and identify the observed differences semi on-line coupling of liquid chromatography to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and Fourier transform infrared spectroscopy (FT-IR) has proved to be very useful.Comprehensive two-dimensional liquid chromatography (2D-LC) was also applied to study the hydrolytic degradation of poly(bisphenol A)carbonate. LC-CC × SEC showed that the formation of poly(bisphenol A)carbonate with OH end-groups occurred over the whole molecular mass range. This information could not be obtained with the separate liquid chromatographic techniques, thereby illustrating the usefulness of 2D-LC.The main degradation processes of poly(bisphenol A)carbonate under the applied hydrolysis conditions turned out to be disappearance of cyclic PC oligomers, chain scission of PC and (subsequent) formation of OH end-groups. FT-IR, SEC and LC-CC have been used to follow the hydrolytic degradation with time. LC-CC proved to be the most promising technique to detect the degradation of poly(bisphenol A)carbonate at an early stage.     

Synthesis of high molecular weight polyester carbonates via interfacial phosgenation of aromatic dicarboxylic acids and bisphenols

The synthesis of bisphenol A poly(carbonate–ester) copolymers was studied by phase-transfer catalysis and modified interfacial polymerization. Only low molecular weight copolymers were prepared directly from dicarboxylic acids, phosgene, and bisphenol A by an interfacial process that involves the use of pyridine as catalyst, HCl acceptor, and weak base. To avoid the use of tertiary amines, which can be difficult to remove from the polymer products, and to produce higher molecular weight copolymers from the same dicarboxylic acid precursors another synthetic method was developed. This more effective method required careful pH control that was achieved by the selective use of the weak-base potassium carbonate in the first stage of the process. Moreover, elevated reaction temperatures (～65–70°C) and phase-transfer catalysis were used. The carbonate–ester copolymers prepared by this technique had consistently high intrinisic viscosities, little or no anyhydride microstructure, and higher degrees of ester unit incorporation than those produced by the pyridine-catalyzed method. These copolymers also had glass transition temperatures (T_g) 20–30°C higher than bisphenol A polycarbonate homopolymer. An analytical method for determining quantitatively the amount of ester units in the bisphenol A poly(carbonate-esters) was developed by using Fourier transform infrared spectroscopy (FT-IR). Agreement between this FT-IR method and a quantitative nuclear magnetic resonance (NMR) method was found to be reasonable, especially for copolymers with ester unit percentages lower than 40%.     

Hyphenation of infrared spectroscopy to liquid chromatography for qualitative and quantitative polymer analysis: degradation of poly(bisphenol A)carbonate

Hyphenation of infrared spectroscopy (IR) to liquid chromatography (LC) has been applied to study chemical changes in poly(bisphenol A)carbonate (PC) as a result of degradation. Especially coupling of LC to FTIR through solvent elimination is a sensitive approach to identify changes in functionality observed in the LC chromatograms as has been demonstrated by coupling of liquid chromatography under critical conditions (LCCC) to IR. Furthermore, an example is shown in which two-dimensional liquid chromatography, i.e. LCCCxSEC, was coupled to IR by means of a flow cell. This resulted in data sets containing most probably valuable data, but extracting relevant information from these large data sets is not straightforward at all. Therefore, multivariate data analysis (MVDA) of SEC-FTIR data was used to extract relevant data from large data sets. This approach revealed chemical differences due to degradation that could not be detected by other means. Spectral features could be identified that allowed to quantitatively predict the degradation of poly(bisphenol A)carbonate as a function of degradation conditions.     

Polyethers derived from bisphenols and highly fluorinated aromatics

A series of fluorinated aromatic polyethers was synthesized via aromatic nucleophilic substitution of highly fluorinated aromatics (1,2,4,5-tetrafluorobenzene, hexafluorobenzene, and decafluorobiphenyl) with bisphenol AF or bisphenol A. Polymerization with 1,2,4,5-tetrafluorobenzene was not observed, and polymerization of hexafluorobenzene with bisphenol proceeded only if the potassium carbonate–bisphenol ratio was carefully controlled. The polymer condensed from decafluorobiphenyl and bisphenol AF was prepared in 77% yield with an inherent viscosity of 1.01 dL/g. The polymer prepared from the condensation of decafluorobiphenyl with bisphenol A was obtained in 48% yield with an inherent viscosity of 0.28 dL/g. These polymers were very soluble in common organic solvents, formed clear, colorless films, and were thermally stable (> 450°C by TGA). The fully fluorinated polymer exhibited low water uptake (0.3%) and dielectric constant (2.17). © 1992 John Wiley & Sons, Inc.     

Catalytic utilization of carbon dioxide to polymer blends via cyclic carbonate

In the present study, the synthesis of bis(cyclic carbonate) from carbon dioxide and bisphenol A (or bisphenol S)-diglycidyl ether was investigated using quaternary ammonium salts as catalyst. Among the salts tested, the one having a larger alkyl group and more nucleophilic counter anion exhibited a better catalytic activity. Poly(hydroxyurethane)s were prepared by the polyaddition reaction of bis(cyclic carbonate) and diamine. The poly(hydroxyurethane) has shown higher thermal stability than conventional polyurethane, and is expected as novel reactive polyurethane. The miscibility of blends containing poly(hydroxyurethena) and poly(styrene-co-acrylonitrile)(SAN) has been also studied by the optical clarity method and DSC.     

Determination of the equilibrium constant for the reaction between bisphenol A and diphenyl carbonate

Despite the industrial significance of poly(bisphenol A carbonate), there is a scarcity of open literature on the equilibrium of the melt‐phase process. In fact, the equilibrium constant (K_eq) for this reaction has never been measured directly. This article describes a process on the basis of NMR for the measurement of K_eq for the reaction between bisphenol A and diphenyl carbonate in the presence and absence of a catalyst. The apparent enthalpy and entropy were calculated using a van't Hoff plot. Decomposition of bisphenol A is a common side reaction in the melt‐phase reaction performed at high temperatures in the presence of catalyst. The effect of these side reactions on the K_eq in the presence of catalyst is determined. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 171–178, 2002     

Synthesis of poly(isopropenylphenoxy propylene carbonate) and its facile side‐chain functionalization into hydroxy‐polyurethanes

4‐Isopropenyl phenol ( 4‐IPP ) is a versatile dual functional intermediate that can be prepared readily from bisphenol‐A ( BPA ). Through etherification with epichlorohydrin to the phenolic group of 4‐IPP , it can be converted into 4‐isopropenyl phenyl glycidyl ether ( IPGE ). On further reaction with carbon dioxide in the presence of tetra‐n‐butyl ammonium bromide ( TBAB ) as the catalyst, IPGE was transformed into 4‐isopropenylphenoxy propylene carbonate ( IPPC ) in 90% yield. Cationic polymerization of IPPC with strong acid such as trifluoromethanesulfonic acid or boron trifluoride diethyl etherate as the catalyst at ?40 °C gave a linear poly(isopropenylphenoxy propylene carbonate), poly( IPPC ), with multicyclic carbonate groups substituted uniformly at the side‐chains of the polymer. The cyclic carbonate groups of poly( IPPC ) were further reacted with different aliphatic amines and diamines resulting in formation of polymers with hydroxy‐polyurethane on side‐chains. Syntheses, characterizations of poly( IPPC ) and its conversion into hydroxy‐polyurethane crosslinked polymers were presented. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 802–808     

含1,2-亚乙基单元的双酚A聚碳酸酯非光气法合成和表征

以双酚A(BPA),碳酸乙二酯(EC)和碳酸二甲酯(DMC)为原料,制备双酚A二元醇(Ⅰ)和双酚A碳酸酯(Ⅱ),并用红外光谱与核磁共振波谱对其结构进行表征.通过Ⅰ与Ⅱ的共缩聚反应及Ⅱ的自聚实现了主链中含有—CH2CH2—单元的双酚A型聚碳酸酯(PC)的非光气法合成,用凝胶渗透色谱法(GPC)和TGA-DSC对PC的分子量和热性质进行分析.结果表明,Ⅱ在240℃自聚6h后产物的Mn可达17.6×103,主链中—CH2CH2—单元的引入,可以降低聚合物的Tg,提高其结晶性,所得聚合物具有良好的热稳定性.     

Syntheses of cyclic polycarbonates by the direct phosgenation of bisphenol M

Bisphenol M was subjected to interfacial polycondensations in an NaOH/CH₂Cl₂ system with triethylamine as a catalyst. Regardless of the catalyst concentration, similar molecular weights were obtained, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra exclusively displayed mass peaks of cycles (detectable up to 15,000 Da). With triethyl benzyl ammonium chloride as a catalyst, linear chains became the main products, but the contents of the cycles and the molecular weights strongly increased with higher catalyst/bisphenol ratios. When the pseudo‐high‐dilution method was applied, both diphosgene and triphosgene yielded cyclic polycarbonates of low or moderate molecular weights. Size exclusion chromatography measurements, evaluated with the triple‐detection method, yielded bimodal mass distribution curves with polydispersities of 5–12. Furthermore, a Mark–Houwink equation was elaborated, and it indicated that the hydrodynamic volume of poly(bisphenol M carbonate) was quite similar to that of poly(bisphenol A carbonate)s with similar concentrations of cyclic species. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1248–1254, 2005     

Selectivity of the cyclic carbonate formation by fixation of carbon dioxide into epoxides catalyzed by Lewis bases

Cyclic carbonate and polycarbonate have been selectively obtained with good conversion by coupling carbon dioxide with diglycidylether of bisphenol A. The ruthenium trichloride supported on tetraethylammonium bromide and polyphosphotungstic acid has been found active and selective to produce the corresponding monomeric and polymeric carbonates. These catalysts can be recycled keeping their high product conversion and selectivity. The heteropolyacid itself showed high activity also under supercritical CO₂ conditions to yield polycarbonate.     

TRANSESTERIFICATION OF POLY（BISPHENOL A CARBONATE） WITH AROMATIC AND ALIPHATIC SEGMENTS IN BUTYLENE TEREPHTHALATE-CAPROLACTONE COPOLYESTER

In this article, the transesterification of poly(bisphenol A carbonate) (PC) with butylene terephthalate-caprolactone copolyester at a weight ratio 50/50 (BCL(21)) was thoroughly investigated by proton nuclear magnetic resonance spectroscopy (^1H-NMR), in conjunction with a model compound. The ^1H-NMR results of the annealed blend PC/BCL(21) show that the formation of bisphenol A-terephthalate ester units is the same as in the annealed blend of PC with PBT, and the transesterification actually occurs between PC and butylene terephthalate (BT) segments in BCL(21). By comparison with the model compound bisphenol A dibutyrate, the new signal appearing at δ=2.56 in the ^1H-NMR spectrum confirms the existence of bisphenol A caprolactone ester units resulting from the exchange reaction of PC with caprolactone (CL) segments. ^1H-NMR analysis of the transesterification rates reveals that the reaction of PC with aromatic and aliphatic segments in BCL(21) proceeds in a random manner. The miscibility of the blend PC/BCL(21) copolyester is favorable for the transesterification of PC with BT segments and CL segments.     

Mesoscale pincushions, microrings, and microdots prepared by heating and peeling of self-organized honeycomb-patterned films deposited on a solid substrate

We describe here a preparation of pincushion structures with holes, hexagonally arranged microrings, and microdots by simple heating and peeling of self-organized honeycomb-patterned films. We have reported that the honeycomb-patterned films can be prepared by casting the solution of an amphiphilic polymer and a hydrophobic polymer under humid conditions. When annealing the honeycomb-patterned films prepared from an amphiphilic copolymer and poly(bisphenol A carbonate), we obtained a variety of mesoscale structures, depending on the heating temperatures. We revealed that these microstructures were formed by using the phase-separation structures in the self-organized honeycomb-patterned films. These micropatterns can be utilized for the template for microelectrodes, superhydrophobic surfaces, photonic crystals, and as a substrate for tissue engineering.     

Surface composition of siloxane-containing polymers

X-ray photoelectron spectroscopy was used to study relationships between the surface and bulk composition in block copolymers and blends of poly(dimethyl-siloxane), poly(bisphenol A sulfone) and poly(bisphenol A carbonate). In all cases the polymer surfaces were highly enriched in siloxane. At a fixed siloxane concentration in the bulk the highest enrichment was observed in the blends of homopolymers and the lowest in the copolymers. It was found that the addition of small quantities of a siloxane-rich copolymer to another copolymer having a lower siloxane content may reduce the surface siloxane concentration of the latter. This unusual surface behavior was explained by the formation of an over-layer in which the macromolecules of the siloxane-rich copolymer are oriented nearly parallel to the sample surface.     

Studies on the synthesis and properties of thermotropic liquid crystalline polycarbonates. VII. Liquid crystalline polycarbonates and poly(ester‐carbonate)s derived from various mesogenic groups

Three series of thermotropic liquid crystalline polycarbonates and poly(ester‐carbonate)s were prepared by solution polycondensation of 4,4′‐biphenyldiol (BP), 4′‐hydroxybiphenyl‐4‐hydroxybenzoate (HHB), or 4‐hydroxyphenyl‐4″‐hydroxybiphenyl‐4′‐carboxylate (HHBP), as mesogenic unit, with 1,10‐bis(p‐hydroxybiphenoxy)decane (N10), bisphenol A (BPA), 4,4′‐dihydroxy‐diphenyl ether (BPO), 4,4′‐[phenylbis(oxy)]bisphenol (BPOO), methylhydroquinone (MeHQ), or phenylhydroquinone (PhHQ). One series of cholesteric poly(ester‐carbonate)s were also prepared by using HHBP, the aromatic diols mentioned above and isosorbide as the chiral moiety. All polycondensations were implemented in pyridine by using triphosgene as the condensation agent. The synthesized polycarbonates were characterized by viscometer, FTIR, DSC, TGA measurements, polarizing microscopy equipped with a heating stage, and WAXD powder pattern. In this study, it was found that the liquid crystalline properties of polycarbonates strongly rely on the mesogenic unit applied. HHBP‐series exhibits a wide temperature region of liquid crystalline (LC) phase even with 50% of bisphenol A (BPA), which is a V‐shaped structure and usually destroys liquid crystalline properties. In addition, homopolycarbonate with HHBP structure possesses extraordinarily low phase‐transition temperature and wide liquid crystalline phase range, due to its asymmetric structure. This asymmetric structure results in head‐to‐tail, head‐to‐head, and tail‐to‐tail random conformation of polymer chain. The isosorbide containing poly(ester‐carbonate)s formed cholesteric phase, which showed homogeneous blue, green, or red Grandjean texture upon shearing in molten state and the Grandjean texture could be frozen easily while quenching the sample to the room temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1852–1860, 2000     

Depolymerization of Poly（bisphenol A carbonate） in Subcritical and Supercritical Toluene

The depolymerization of poly(bisphenol A carbonate)(PC) in subcritical and supercritical toluene was studied. The experimental parameters, which influence the depolymerization reaction such as temperature (570-633 K), pressure (4.0-7.0 MPa), reaction time (5-60 min), and toluene to PC weight ratio (3.0-11.0), were investigated, and the reaction products were determined by GC, GC/MS and FT-IR spectrometer. It was found that the main product of the depolymerization reaction was bisphenol A(BPA). BPA accounted for over 55.7% of the depolymerization products at reaction temperature 613 K, pressure 5.0-6.0 MPa, reaction time 15 min and toluene/PC weight ratio of around 7.0.     

Sulfur containing polymers.: Aromatic polydithiocarbonates and polythiocarbonates: synthesis and thermal properties

New polydithiocarbonates and polythiocarbonates were obtained by interfacial polymerization of bis(4-mercaptophenyl)methane, bis(4-mercaptophenyl)ether and bis(4-mercaptophenyl)sulfide with phosgene, bisphenol A bischloroformate and bisphenol A polycarbonate oligomers (-OH/-O-CO-Cl terminated). Polymerization process was carried out under interfacial conditions using a phase-transfer catalyst, as earlier described for the synthesis of polydithiocarbonates and polythiocarbonates from 2,2-bis(4-mercaptophenyl)propane. The structures of the polymers were examined by IR and NMR spectroscopies; their thermal properties were investigated by thermogravimetric analysis and differential scanning calorimetry. In particular, the effect of the substitution of one or both the ethereal oxygen atoms of the carbonate group by sulfur has been analyzed by comparing the T_g values and the ability to crystallize of the sulfur containing polymers with those of the corresponding polycarbonates.     

Local order in polycarbonate glasses by 13C{19F} rotational‐echo double‐resonance NMR

Nearest‐neighbor chain packing in a homogeneous blend of carbonate ¹³C‐labeled bisphenol A polycarbonate and CF₃‐labeled bisphenol A polycarbonate has been characterized using a shifted‐pulse version of magic‐angle spinning ¹³C{¹⁹F} rotational‐echo double‐resonance (REDOR) NMR. Complementary NMR experiments have also been performed on a polycarbonate homopolymer containing the same ¹³C and ¹⁹F labels. In the blend, the ¹³C observed spin was at high concentration, and the ¹⁹F dephasing or probe spin was at low concentration. In this situation, an analysis in terms of a distribution of isolated heteronuclear pairs of spins is valid. A comparison of the results for the blend and homopolymer defines the NMR conditions under which higher concentrations of probe labels can be used and a simple analysis of the REDOR results is still valid. The nearest neighbors of a CF₃ on one chain generally include a carbonate group on an adjacent chain. A direct interpretation of the REDOR total dephasing for the polycarbonate blend indicates that at least 75% of carbonate‐carbon ¹³C ··· F₃ nearest neighbors are separated by a narrow distribution of distances 4.7 ± 0.3 Å. In addition, analysis of the variations in REDOR spinning‐sideband dephasing shows that most of the ¹³C ··· F₃ dipolar vectors have a preferred orientation relative to the polycarbonate mainchain axis. This combination of distance and orientational constraints is interpreted in terms of local order in the packing of the carbonate group of one polycarbonate chain relative to the isopropylidene moiety in a neighboring chain. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2760–2775, 2006