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Showing papers on "Polycarbonate published in 2017"


Journal ArticleDOI
Ye Liu1, Hui Zhou1, Jia-Zhi Guo1, Wei-Min Ren1, Xiao-Bing Lu1 
TL;DR: A novel recyclable plastic: degradable polycarbonate synthesized by dinuclear chromium-complex-mediated copolymerization of CO2 with 1-benzyloxycarbonyl-3,4-epoxy pyrrolidine, a meso-epoxide in quantitative yield under mild reaction conditions is reported.
Abstract: It is of great significance to depolymerize used or waste polymers to recover the starting monomers suitable for repolymerization reactions that reform recycled materials no different from the virgin polymer. Herein, we report a novel recyclable plastic: degradable polycarbonate synthesized by dinuclear chromium-complex-mediated copolymerization of CO2 with 1-benzyloxycarbonyl-3,4-epoxy pyrrolidine, a meso-epoxide. Notably, the novel polycarbonate with more than 99 % carbonate linkages could be recycled back into the epoxide monomer in quantitative yield under mild reaction conditions. Remarkably, the copolymerization/depolymerization processes can be achieved by the ON/OFF reversible temperature switch, and recycled several times without any change in the epoxide monomer and copolymer. These characteristics accord well with the concept of perfectly sustainable polymers.

145 citations


Journal ArticleDOI
TL;DR: In this article, the feasibility of laser-assisted direct joining of carbon fibre reinforced polymer (CFRP) with thermosetting matrix to polycarbonate sheets is investigated by means of a high-power diode laser with a maximum power of 200 W.
Abstract: Laser-Assisted Direct Joining (LADJ) has been employed for a wide variety of materials including metals, thermoplastics and reinforced thermoplastics. The feasibility of Laser-Assisted Direct Joining (LADJ) of Carbon Fibre Reinforced Polymer (CFRP) with thermosetting matrix to polycarbonate sheets is investigated in this work. The process was performed by means of a high-power diode laser with a maximum power of 200 W. Experimental tests were carried out by varying the main process conditions including the laser power and scanning speed. Morphological analysis using Optical and Scanning Electron Microscopy (SEM) as well as mechanical characterization of the welds were performed to understand the influence of the processing conditions on the weld quality, defects, and strength. Preliminary results have been encouraging: the process consists in removing the exterior epoxy layer from the CFRP and the adhesion of the carbon fibres to the PC. According to the achieved findings, the mechanical strength of the welds was highly affected by the Linear Energy Density (LE): low values of LE resulted in poor adhesion of the polycarbonate through the carbon fibres, which led to poor mechanical fastening and adhesion. On the other hand, processing conditions leading to excessive values of LE resulted in considerable damage of the composite matrix (the epoxy resin underlying the exposed carbon-fibre layer) and formation of bubbles on the PC substrate, which produced a dramatic reduction of the mechanical behaviour of the welds. The apparent shear strength, calculated as the ultimate shear force by the effective adhesion area was 8.4 MPa.

57 citations


Journal ArticleDOI
05 May 2017-Polymer
TL;DR: In this paper, a series of copolycarbonates of ISB, a bio-derived diol with a rigid heterocyclic structure, and ductile CHDM monomers with diphenyl carbonate were prepared by transesterification polymerization.

56 citations


Journal ArticleDOI
01 Oct 2017-Carbon
TL;DR: In this article, the coefficient of friction (COF) and wear of polyethyleneimine/graphene oxide thin films, (PEI/GO)15, on steel display superlubricity against a steel counterface ball.

47 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of aromatic, π electron interactions on miscibility and on the structure and properties of polypropylene (PP)/lignin blends were used as a reference.
Abstract: Polymer/lignosulfonate blends were prepared from three polymers containing an aromatic moiety in their chain: polystyrene (PS), polycarbonate (PC), and a glycol modified poly(ethylene terephthalate) (PETG), in order to study the effect of aromatic, π electron interactions on miscibility and on the structure and properties of the blends. Polypropylene (PP)/lignin blends were used as a reference. The components were homogenized in an internal mixer and compression molded into plates of 1 mm thickness. Structure was characterized by scanning electron microscopy (SEM) and image analysis, while mechanical properties were characterized by tensile testing and acoustic emission measurements. Component interactions were estimated from solubility parameters, the composition dependence of glass transition temperature, and mechanical properties. The results indicated that π electron interactions result in better compatibility than the dispersion forces acting in PP blends. The average size of the dispersed lignin par...

46 citations



Journal ArticleDOI
TL;DR: In this article, the first implementation of the aliphatic polycarbonate PTMC as a non-polyether host matrix in solid-state sodium batteries was described, and the functionality of PTMC-NaTFSI was demonstrated through cycling of Na/Prussian blue halfcells displaying high discharge capacities and limited polarization at C/10 and 60°C.

39 citations


Journal ArticleDOI
TL;DR: In this article, the effect of compatibilization on the mechanical properties of polypropylene and polycarbonate (PP/PC) composites was investigated and the results indicated that the deposition orientation has a significant influence on the structural properties of PP/PC composite FDM parts.
Abstract: Purpose Although the feasibility and effectiveness of the fused deposition modeling (FDM) method have been proposed and developed, studies of applying this technology to various materials are still needed for researching its applicability, especially with regard to polymer blends and composites. The purpose of this paper is to study the deposition-induced effect and the effect of compatibilizers on the mechanical properties of polypropylene and polycarbonate (PP/PC) composites. Design/methodology/approach For this purpose, three different deposition modes for PP/PC composites with or without compatibilizers were used for the FDM method and tested for tensile properties. Also, parts with the same materials were made by injection molding and used for comparison. In addition, different deposition speeds were used to investigate the different deposition-induced effects. Furthermore, the behavior of the mechanical properties was clarified with scanning electron microscope images of the fracture surfaces. Findings The research results suggest that the deposition orientation has a significant influence on the mechanical behavior of PP/PC composite FDM parts. The results also indicate that there is a close relationship between the mechanical properties and morphological structures which are deeply influenced by compatibilization. Compared with injection molded parts, the ductility of the FDM parts can be dramatically improved due to the formation of fibrils and micro-fibrils by the deposition induced during processing. Originality/value This is the first paper to investigate a PP/PC composite FDM process. The results of this paper verified the applicability of PP/PC composites to FDM technology. It is also the first time that the deposition-induced effect during FDM has been investigated and studied.

36 citations


Journal ArticleDOI
TL;DR: In this article, an efficient approach for the fabrication of polymer blend nanocomposites with well-dispersed graphene oxide in polycarbonate (PC)/poly methyl methacrylate (PMMA) through melt compounding under the controlled temperature and pressure was reported.

35 citations


Journal ArticleDOI
TL;DR: The utilization of in-situ SAXS in addition to the thermomechanical analysis will render the qualitative and quantitative details about the interfacial zone and its effect on thermal and mechanical properties of nanocomposite at varying temperature conditions.
Abstract: The inorganic and organic nanocomposites have enticed wide interest in the field of polymer-based composite systems to augment their physiochemical properties like mechanical strength and electrical conductivity. Achieving interfacial interaction between inorganic filler and polymer matrix is a recurring challenge, which has significant implications for mechanical properties of nanocomposites. In this context, the effect of "interfacial zone" on structural and thermal attributes of the melt blended pristine polycarbonate and polycarbonate (PC) decorated fumed silica nanocomposite have been examined from ambient temperature to the glass transition temperature. Thermomechanical characterization and in-situ temperature assisted small angle X-ray scattering technique (SAXS) were used for contemplating quantitative and qualitative molecular dynamics of developed nanocomposites. Though, the FT-IR spectra have demonstrated some extent of interaction between inorganic and organic groups of composite, the reduced glass transition temperature and storage modulus was ascertained in DMA as well as in DSC, which has been further confirmed by in-situ temperature assisted SAXS. It is envisioned that the utilization of in-situ SAXS in addition to the thermomechanical analysis will render the qualitative and quantitative details about the interfacial zone and its effect on thermal and mechanical properties of nanocomposite at varying temperature conditions.

34 citations


Journal ArticleDOI
TL;DR: A polymer nanocomposite produced by ultrasonic-assisted dispersion of multiwalled carbon nanotubes in a polycarbonate matrix using p-xylene and dichloromethane as the solvents and revealed enhanced thermal stability and decreased crystallinity, respectively, as compared to the neat polymer.
Abstract: A polymer nanocomposite was produced by ultrasonic-assisted dispersion of multiwalled carbon nanotubes (MWCNTs) in a polycarbonate matrix using p-xylene and dichloromethane as the solvents The filler loading was varied from 1 to 3 wt % in order to examine the effect of MWCNTs on the structure and properties of the composites The nanocomposites were characterized by DSC, DTA, TGA, UV-vis, FTIR and Raman spectroscopy to evaluate the changes induced by the filler in the polymer matrix UV-vis, FTIR and Raman spectroscopy measurements confirmed the presence of the dispersed phase in the composite films, while TGA and DSC analysis of the nanocomposites revealed enhanced thermal stability and decreased crystallinity, respectively, as compared to the neat polymer The proposed composites can find application in a number of everyday products where polycarbonate is the base polymer

Journal ArticleDOI
TL;DR: In this article, both surface-coating and hot-pressing methods were adopted to prepare specimens for evaluating the carbon fiber/polycarbonate interfacial adhesion properties by single-filament fragmentation tests.

Book ChapterDOI
01 Jan 2017
TL;DR: The most widely used process for the production of polycarbonate (PC) is interfacial polycondensation, involving the reaction of BPA with phosgene, which is usually described as an engineering plastic.
Abstract: This chapter covers the chemistry, technology, engineering, and marketing of polycarbonate (PC), which is usually described as an engineering plastic. Bisphenol A (BPA) PC was first produced in 1958. The most widely used process for the production of PCs is interfacial polycondensation, involving the reaction of BPA with phosgene. BPA PCs have an average molar mass of 20–50 kg mol −1 . Its important properties are extreme toughness, high heat distortion temperature, very good electrical insulation characteristics, and excellent transparency. Its main disadvantages are the need to dry before processing, limited resistance to chemicals and UV light, and notch sensitivity. Glass-reinforced grades with increased rigidity are available, as are blends with polybutylene terephthalate, polyethylene terephthalate, and polymethyl methacrylate. Important application areas for PC are optical/lighting, glass replacement, medical packaging, electrical products, automotive engineering, household products, and safety applications. CD production is of course a very well-known use.

Journal ArticleDOI
TL;DR: In this paper, the melting of polycarbonate and graphene nanoplatelets was used to obtain nanocomposite materials with enhanced mechanical and barrier properties, and the properties of these materials were thoroughly characterized using broad band dielectric spectroscopy, thermally stimulated depolarization currents, differential scanning calorimetry, tensile testing, dynamic mechanical thermal analysis and water vapor, carbon dioxide and oxygen permeability measurements.
Abstract: Nanocomposites based on polycarbonate (PC) and different amounts of untreated graphene nanoplatelets (GnP) (from 1 to 7 wt %) were prepared by melt blending. The nanocomposites were thoroughly characterized employing the following techniques: broad band dielectric spectroscopy, thermally stimulated depolarization currents, differential scanning calorimetry, tensile testing, dynamic mechanical thermal analysis, and water vapor, carbon dioxide and oxygen permeability measurements. The presence of a MWS relaxation mode indicated the accumulation of electrical charges trapped at the interfaces of the polycarbonate with graphene 2D platelets. The addition of GnP produced nanocomposite materials with enhanced mechanical and barrier properties. The melt mixed PC/graphene nanocomposites prepared here exhibit well-balanced properties, even though unmodified graphene nanoplatelets were used. In addition, the nanocomposites were obtained by a single extrusion process, which is easily scalable for industrial applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 134, 44654.

Journal ArticleDOI
TL;DR: In this paper, a series of polycarbonate polyurethanes were fabricated using a two-step bulk reaction by the melting pre-polymer solution-casting method in order to synthesize biomedical polyurethsane elastomers with good mechanical behavior and biostability.
Abstract: In this study, we have fabricated a series of polycarbonate polyurethanes using a two-step bulk reaction by the melting pre-polymer solution-casting method in order to synthesize biomedical polyurethane elastomers with good mechanical behavior and biostability. The polyurethanes were prepared using dibutyltin dilaurate as the catalyst, poly(1,6-hexanediol)carbonate microdiols (PCDL) as the soft segment, and the chain extender 1,4-butanediol (BDO) and aliphatic 1,6-hexamethylene diisocyanate (HDI) as the hard segments. The chemical structures and physical properties of the obtained films were characterized by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and mechanical property tests. The surface properties and degrees of microphase separation were further analyzed by water droplet contact angle measurements (CA) and atomic force microscopy (AFM). The materials exhibited a moderate toxic effect on the tetrazolium (MTT) assay and good hemocompatibility through hemolytic tests, indicating a good biocompatibility of the fabricated membranes. The materials could be considered as potential and beneficial suitable materials for tissue engineering, especially in the fields of artificial blood-contacting implants or other biomedical applications.

Journal ArticleDOI
TL;DR: Hybrid transparent coatings based on zirconia nanoparticle fillers and epoxy resin were designed to increase scratch resistance of commodity polymers without impairing their optical properties.

Journal ArticleDOI
TL;DR: Hard, scratch-resistant and transparent fluoropolymer-based hybrid coatings are successfully prepared through the sol-gel chemistry and investigated, in the attempt to correlate the chemical, physical and surface properties of these materials with the mechanical properties measured at the nanoscale by atomic force microscopy (AFM) as mentioned in this paper.
Abstract: Hard, scratch-resistant and transparent fluoropolymer-based hybrid coatings are successfully prepared through the sol-gel chemistry and investigated, in the attempt to correlate the chemical, physical and surface properties of these materials with the mechanical properties (i.e. hardness and elastic modulus) measured at the nanoscale by atomic force microscopy (AFM). The organic component of these coatings consists in a hydroxyl-functional fluoropolymer resin, which belongs to the class of chlorotrifluoroethylene-vinylether copolymers and exhibits remarkable properties such as easy handling, great weather resistance, good adhesion and flexibility of coatings. A functionalization of this copolymer is also performed using an isocyanate-functionalized silane in order to assure a covalent cross-linking of organic fluorinated resin with inorganic phases. The combination of the silanized chlorotrifluoroethylene-vinylether copolymer with different sols composed of silica and zirconia is used to obtain high scratch resistance and high durability coatings on polycarbonate. A series of three hybrid coatings with different zirconia/silica molar ratios (0.09/0.48) are developed and analyzed by differential scanning calorimetry (DSC), water contact angle measurements, pencil hardness and adhesion tests. AFM scratch hardness, coating wettability and surface composition measured by Fourier transform infrared spectroscopy (FTIR) are regularly monitored over long-term UV–vis light exposure, to assess the durability of the hybrid coatings. Interestingly, the hybrid fluorinated coatings exhibit an improved scratch resistance and a superior long-term stability when exposed to an accelerated weathering, compared to pristine PC substrates. The mixed silica/zirconia hybrid coatings with a low and intermediate zirconia-to-silica ratio also show excellent mechanical strength, high level of hardness and superior integrity after long-term light exposure.

Journal ArticleDOI
TL;DR: In this article, the development of one-pot, two-step processes for the synthesis of di-and tri-block polymers was reviewed and a methodology for the preparation of polycarbonate diols of well-defined molecular weights with narrow polydispersities is presented using (salen)CoX/onium salt catalyst systems.
Abstract: This minireview's primary focus is to review recent studies from my research program on the development of one-pot, two-step processes for the synthesis of di- and tri-block polymers. In all of these prepared polymeric materials at least one component is a polycarbonate derived from the copolymerization of CO2 and epoxides. Synthetic methodology for the preparation of polycarbonate diols of well-defined molecular weights with narrow polydispersities are presented using (salen)CoX/onium salt catalyst systems. These polyols were subsequently utilized in the synthesis of di-and tri-block polylactide/polycarbonate or polyphosphoester/polycarbonate polymers employing organocatalysts. In addition, the introduction of these polyols to a second epoxide/CO2 copolymerization process provided block polycarbonate materials. Of particular interest, the first or second epoxide monomer incorporated into the copolymer can possess vinyl groups for postpolymerization modification by thiol–ene chemistry. These degradable polymeric materials have significant potential for use in biomedical applications.

Journal ArticleDOI
TL;DR: In this paper, a friction stir welding method was used to join polycarbonate composites, which was shown to be effective in the field of polymer welding, but challenges still remain in using a friction-stir welding method to join polymer composites.
Abstract: Although considerable progress has been made in recent years in field of polymer welding, challenges still remain in using a friction stir welding method to join polycarbonate (PC) composites. This...

Journal ArticleDOI
TL;DR: In this article, an innovative self-stratifying coating, based on an epoxy/silicone blend, has been developed and applied on a plastic substrate (Polycarbonate), which is evidenced by microscopic analysis coupled with X-ray mappings.

Journal ArticleDOI
TL;DR: In this article, polycarbonate/silica nanocomposite membranes at low silica loading were fabricated by solution blending and solvent evaporation technique using 3-aminopropyl trimethoxysilane in the sol-gel process.
Abstract: Polycarbonate/silica nanocomposite membranes at low silica loading were fabricated by solution blending and solvent evaporation technique. The functionalized silica nanoparticles used were synthesized by co-condensing hydrolyzed tetraethylorthosilicate with 3-aminopropyl trimethoxysilane in the sol–gel process. The membranes morphology, composition, surface, structure, thermal and mechanical properties were analyzed by the standard characterization techniques. The gas permeation tests were conducted in four-channel permeation cells. Field emission scanning electron microscopy results reveal that membranes above 3 wt % silica content formed distinguishable voids and agglomerates. Fair distribution of silica nanoparticles and absence of residual solvents were observed by energy dispersive X-ray and thermogravimetric analysis. Fourier transform infrared spectroscopy spectra confirmed the presence of new functional groups (NH) and (OH) bonds. The X-ray diffraction pattern revealed the polymer-particle interactions, the formation of rigidified polymer chain, and nanostructured silicon crystals. Further, the thermogravimetric analysis results revealed thermal stability enhancement while differential scanning calorimetry results of increased glass transition temperatures confirmed the presence of rigidified polymer chain. Furthermore, enhancements in mechanical strength of the membranes were observed. Moreover, at all feed pressures, increased CO2, N2, and CH4 gas permeation was observed. At 6 bar feed pressure, the CO2/N2 and CO2/CH4 ideal selectivities of PC membranes with 3 wt % silica loading have increased from 19.2 to 38.0 and 29.2, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45310.

Journal ArticleDOI
TL;DR: In this article, the reversible linkages within the network are based on a Hetero-Diels-Alder (HDA) moiety, which is able to undergo cleavage and rebonding as a function of temperature within minutes.

Journal ArticleDOI
TL;DR: In this paper, hyperbranched, multifunctional polycarbonate polyols based on CO2, cyclohexene oxide (CHO), and the "inimer" (initiator-monomer) (4-hydroxymethyl)cyclohexenes oxide (HCHO) were prepared in one-pot syntheses.
Abstract: Hyperbranched, multifunctional polycarbonate polyols based on CO2, cyclohexene oxide (CHO), and the “inimer” (initiator–monomer) (4-hydroxymethyl)cyclohexene oxide (HCHO) were prepared in one-pot syntheses. The related linear poly(hydroxymethyl cyclohexene carbonate) structures based on protected HCHO and postpolymerization deprotection were also synthesized as model compounds. The content of hydroxyl functionalities was adjustable for both linear and hyperbranched terpolymer systems. All CO2/epoxide polymerizations were catalyzed by the (R,R)-(salcy)-Co(III)Cl complex. The polycarbonates obtained were comprehensively investigated using various 1D and 2D NMR techniques, SEC, FT-IR, UV–vis spectroscopy, and contact angle measurements. Rigid polyols with molecular weights between 3600 and 9200 g mol–1 and moderate dispersity between 1.18 and 1.64 (Mw/Mn) were obtained. In addition, the materials were examined with respect to their thermal properties, intrinsic viscosity, and their three-dimensional structur...

Journal ArticleDOI
TL;DR: In this article, the functionalized boron nitride nanotubes (f-BNNTs) were characterized by FTIR, 1H NMR, TGA, and SEM.
Abstract: The novel derivatization of boron nitride nanotubes (BNNTs) with two organic peroxides (lauroyl peroxide and dicumyl peroxide) is presented. The functionalized-BNNTs (f-BNNTs) were characterized by FTIR, 1H NMR, TGA, and SEM. These thermally labile peroxides can decompose to generate an alkoxyl radical, or an alkyl radical (with the loss of CO2), which then acts as a Lewis base to attack the electron-deficient boron sites of BNNTs. This results in the covalent formation of R-O-BNNT or R-BNNT bonds. Thin films (15 to 35 μm thickness) of 0.5 to 1.0 wt% lauryl-BNNT/polycarbonate and 1 wt% BNNT-OH/polycarboante composites were fabricated, and their transparency was demonstrated. Semi-transparent, hot-pressed disks (200 μm thickness) of 1.0 wt% cumyloxy-BNNT/polycarbonate and 1.0 wt% lauryl-BNNT/polycarbonate composites were also fabricated and mechanically tested. The Young's modulus and the maximum tensile stress were increased by 12% and 8%, respectively, compared to the corresponding properties of BNNT-free polycarbonate samples.

Journal ArticleDOI
TL;DR: Bonding strength is presented using a shear strength test and a crack opening method in addition to the fluidic leakage inspection to bond PMMA microchip to PC film.
Abstract: Recently, thermoplastic polymers have become popular materials for microfluidic chips due to their easy fabrication and low cost. A polymer based microfluidic device can be formed in various fabrication techniques such as laser machining, injection molding, and hot embossing. A new bonding process presented in this paper uses a 2.5% (w/w) polymethyl methacrylate (PMMA) solution as an adhesive layer to bond dissimilar polymers—PMMA to polycarbonate (PC)—to enclose the PMMA microfluidic channels with PC. This technique has been successfully demonstrated to bond PMMA microchip to PC film. This paper presents bonding strength using a shear strength test and a crack opening method in addition to the fluidic leakage inspection.

Journal ArticleDOI
TL;DR: In this paper, two series of high-molar-mass thermoplastic poly(carbonate-urethane)s (PCURs) were synthesized from nonconventional sulfur-containing chain extenders, i.e., 2,2′-[sulfanediylbis(benzene-1,4-diyloxy)]diethanol (diol SE) and 2, 2′-[methanediylonbis(methanedylmethane-1-4-methnediyls sulfanedi
Abstract: Two series of high-molar-mass thermoplastic poly(carbonate–urethane)s (PCURs) were synthesized from nonconventional sulfur-containing chain extenders, i.e., 2,2′-[sulfanediylbis(benzene-1,4-diyloxy)]diethanol (diol SE) and 2,2′-[methanediylbis(benzene-1,4-diylmethanediylsulfanediyl)]diethanol (diol ME), 1,1′-methanediylbis(4-isocyanatobenzene) and 30, 45 and 60 mol% aliphatic polycarbonate diol of M n = 2000 g mol−1 (Desmophen® C2200, Bayer) via a one-step melt polyaddition. The PCURs were investigated by FTIR, UV–Vis, atomic force microscopy, X-ray diffraction analysis, differential scanning calorimetry, thermogravimetry (TG) and TG-FTIR. Moreover, their Shore A/D hardness, tensile, adhesive and optical properties were determined. The obtained PCURs were transparent or opaque elastomers, possessing amorphous or partially crystalline structures. The polymers based on diol ME showed lower glass transition temperatures (−9 to (−8) vs. −7 to 20 °C) and better microphase separation. All the PCURs exhibited a relatively good thermal stability. Their temperature of 1 % mass loss was within the range of 284–292 °C with somewhat higher values shown by those obtained from diol ME. The PCURs decomposed in two (from diol ME) or three (from diol SE) stages, and for both types of polymers, the main decomposition occurred at the first stage. All the PCURs based on diol SE exhibited higher tensile strength (33.5–41.9 vs. 27.0–31.5 MPa), but smaller elongation at break (300–400 vs. 450–550 %) than polymers derived from diol ME. Somewhat better adhesive properties and a slightly higher refractive index were found for polymer based on diol ME with two sulfur atoms.

Journal ArticleDOI
TL;DR: A redox-responsive poly(vinyl cyclohexene carbonate) (PVCHC) with detachable disulfide-bond backbone is synthesized in a controllable manner by combination of immortal copolymerization and prereaction approach, and functional aliphatic polycarbonates having well-defined architecture and narrow polydispersity can be prepared.
Abstract: Due to the axial group initiation in traditional (salen)CoX/quaternary ammonium catalyst system, it is difficult to construct single active center propagating polycarbonates for copolymerization of CO2 /epoxides. Here a redox-responsive poly(vinyl cyclohexene carbonate) (PVCHC) with detachable disulfide-bond backbone is synthesized in a controllable manner using (salen)CoTFA/[bis(triphenylphosphine)iminium, [PPN]TFA binary catalyst, where the axial group initiation is depressed by judiciously choosing 3,3'-dithiodipropionic acid as starter. While for those comonomers failing to obtain polycarbonate with unimodal gel permeation chromatography (GPC) curve, a versatile method is developed by combination of immortal copolymerization and prereaction approach, and functional aliphatic polycarbonates having well-defined architecture and narrow polydispersity can be prepared. The resulting PVCHC can be further functionalized with alkenes by versatile cross-metathesis reaction to tune the physicochemical properties. The combination of immortal polymerization and prereaction approach creates a powerful platform for controllable synthesis of functional CO2 -based polycarbonates.

Journal ArticleDOI
TL;DR: In this paper, a new eco-friendly strategy for the preparation of linear and hyperbranched polycarbonates was developed, which used equimolar amounts of DMC to avoid waste and the disposal of excess DMC.
Abstract: A new eco-friendly strategy for the preparation of linear and hyperbranched polycarbonates was developed. Our work referred to a one-pot condensation polymerization of various alcohols (diols and triols) with equivalent amounts of eco-friendly dimethyl carbonate (DMC) at 120 °C, atmospheric pressure and in 1,4-dioxane solution using 4-dimethylaminopyridine (DMAP) or lithium acetylacetonate (LiAcac) as a catalyst. Polymer chains were built by pure transesterification of hydroxyl and methyl carbonate chain ends, and the single byproduct (methanol) was removed using a pressure-equalized addition funnel filled with 4 A molecular sieves as the crucial equipment in this work. Using this strategy, hyperbranched polycarbonates with high molar masses (Mn up to 10 000 g mol−1 and Mw up to 64 000 g mol−1) and high hydroxyl end group contents (up to 94%) were successfully prepared using dimethyl carbonate instead of toxic phosgene or phosgene-based monomers for the first time. In addition, linear aliphatic polycarbonates of various diols were also synthesized with Mn up to 16 000 g mol−1 and low molar mass distributions (ĐM < 1.70). Another eco-friendly aspect of this work was the use of equimolar amounts of DMC to avoid waste and the disposal of excess DMC; in a classic 2-step polycondensation for polycarbonate synthesis excess DMC is a prerequisite in order to obtain high molar masses.

Journal ArticleDOI
TL;DR: Hydrophobic recovery of UVO-treated plastics can be inhibited by storing them in dehumidified or vacuum conditions.
Abstract: Thermoplastics are becoming a popular material for fabricating microfluidic devices and there is an increasing need for robust surface modification strategies. UV/ozone (UVO) treatment is a simple and effective method for making plastic surfaces more hydrophilic. Prior reports on the stability of UVO-treated plastics are limited to four weeks, which is not sufficient for applications requiring long-term storage. Here, we present new findings on the long-term stability of UVO-treated plastics for up to 16 weeks and show that the storage condition has a significant impact on the surface stability. Static contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were performed on UVO-treated cyclic olefin copolymer (COC), polycarbonate (PC) and poly(methyl methacrylate) (PMMA) stored in air, dehumidified and vacuum conditions. We found that the hydrophobic recovery of UVO-treated COC and PC can be inhibited by storing them in dehumidified or vacuum conditions, whereas the stability of PMMA is not significantly influenced by the storage condition. Protein adsorption studies were carried out and showed that there is a significant reduction in the amount of protein adsorption on UVO-treated plastics compared with untreated plastics. Lastly, UVO-treated PMMA microchannels were fabricated and used for capillary-driven flow, which revealed that longer treatment durations generate faster flow rates. These collective results offer new insights into the utility of UVO-treated plastics for microfluidic analytical applications.

Journal ArticleDOI
TL;DR: In this paper, the distribution of the constituent polymers of an injection-molded product comprising a miscible blend of polycarbonate (PC) and low-molecular-weight poly(methyl methacrylate) (PMMA) was investigated.
Abstract: We investigated the distribution of the constituent polymers of an injection-molded product comprising a miscible blend of polycarbonate (PC) and low-molecular-weight poly(methyl methacrylate) (PMMA). We found that PMMA became localized at the surface without affecting the transparency of the product. As a result, the surface hardness was effectively enhanced by a small amount of PMMA. This technique can be used to produce an ideal plastic glass that has high transparency, mechanical toughness, and high surface hardness.