Hyperbranched thermolabile polycarbonates derived from a A2+B3 monomer system

Hyperbranched polycarbonates were synthesized successfully via the A₂ + B₃ route by the reaction of a bis(carbonylimidazolide) with triethanolamine. These polymers containing the carbonate group as thermolabile moiety are decomposing into volatile products at around 200°C. The polymers were characterized with ¹H/¹³C NMR spectroscopy, SEC, DSC and TGA techniques.     

Synthesis,characterization, thermal stability and compatibility properties of new energetic polymers

Four new cross-linked polymers poly(vinyl m-nitrobenzene)-polyglycidylazides (PVMNB-GAPs) were successfully synthesized using toluene diisocyanate as the cross-linking agent. Their structure was confirmed by their FTIR, UV–Vis, ¹H and ¹³C NMR spectroscopy. Moreover, the thermal properties of cross-linked polymers were evaluated by DTA, TGA and DSC techniques, which confirmed that synthesized polymers exhibited good resistance to thermal decomposition up to 200°C. In addition, their compatibility with the main energetic components of 2,4,6-trinitrotoluene-based melt-cast explosives were also evaluated by the non-isothermal differential thermal analysis method.     

Liquid crystalline and photoactive poly[4,4′-stilbeneoxy]alkylbiphenylphosphates

A series of liquid crystalline and photoactive polymers were synthesized from biphenylphosphorodichloridate with various 4,4′-bis(m-hydroxyalkyloxy)stilbenes (m = 2, 4, 6, 8, 10) in chloroform by solution polycondensation method using an acid scavenger. The resultant polymers were characterized by inherent viscosity, FT-IR, ¹H, ¹³C and ³¹P NMR spectroscopies. The liquid crystalline (LC) properties were studied using HOPM and DSC and it was inferred that out of the five polymers synthesized, higher methylene chain containing polymers (m = 6, 8, 10) exhibited LC properties. Thermogravimetric analysis revealed that all the polymers were stable in between 290 and 367 °C and underwent degradation thereafter. The thermal stability and char yield of the polymers decreased with increase in flexible methylene chain. The photochemical properties of these polymers were investigated by UV and fluorescence spectroscopy. Crosslinking proceeds via 2π-2π cycloaddition reaction of the -CHCH- of the stilbene moieties. The rate of crosslinking increases with increase in methylene chain length in the polymer backbone. The fluorescence spectra showed that the longer methylene spacer containing polymers exhibited larger red-shifts than the shorter spacer containing polymers.     

Synthesis of multi-arm star polystyrene with hyperbranched polyether core

Multi-arm star polystyrenes with hyperbranched poly(3-ethyl-3-oxetanemethanol) (PEOM, 3) core were synthesized by atom transfer radical polymerization (ATRP) method. The structures of polymers were confirmed by FT-IR and ¹H NMR. GPC results showed that the resultant polymers had relatively low polydispersity indices (PD = 1.47-2.03). DSC analysis indicated that polystyrene star polymers had a glass transition temperature (T_g = 42.2-91.5 °C) that changed with the amount of the polystyrene in the polymers. In addition, the aggregation behavior of the multi-arm star polystyrenes in a selective solvent (THF/cyclohexane) was probed with polystyrene arms that encapsulated in the aggregates and PEOM cores hidden in the center of the micelles.     

Poly(methylene sebacate): Synthesis and characterization

The synthesis of poly(methylene sebacate) was carried out via the reaction of cesium sebacate with bromochloromethane in N-methylpyrrolidone over a range of temperatures (55–130°C). A number of polymers having limiting viscosity numbers in the range of 0.29–0.94 dL g^?1 (CHCl₃; 25°C) were characterized by elemental analyses, ¹H- and ¹³C-NMR, DSC, and GPC techniques. The polymerization was found to be very rapid at 100°C, being complete in ca. 15 min. and was relatively insensitive to the stoichiometric ratio of the monomers. As high molecular weight polymers were produced without the quantitative conversion of the reactants, the polymerization is considered to be occurring by an interfacial mechanism.     

Synthesis, characterization and properties of naphthoxazine-functional poly(propyleneoxide)s

Thermally curable naphthoxazine-functionalized polymers were synthesized by the reaction of linear (diamines) and branched (triamines) poly(propyleneoxide)s (Jeffamine series) having various molecular weights, with p-formaldehyde, and 2-naphthol. The structures of the resulting polymers were characterized by using FT-IR and ¹H-NMR. In addition, curing behavior of these polymers was studied using differential scanning calorimeter (DSC). Hydrophilicity of these polymers, both in cured and non-cured states, was investigated by water contact angle measurements. The surface topographies of the polymers were also examined by atomic force microscope (AFM).     

Synthesis and cure kinetics of diphenyl(diphenylethynyl)silane monomer

Diphenyl(diphenylethynyl)silane ((ph–C≡C)₂–Si–ph₂) (DPDPES) was synthesized by the Grignard reaction. The corresponding isothermal and non-isothermal cure kinetics of DPDPES were analyzed by using differential scanning calorimetry (DSC), and the molecular structure was characterized by H-NMR. The results showed that all the cure curves were typically sigmoid shape and cure reactions could be described by an autocatalytic kinetic model by isothermal DSC. The kinetic data, for example, activation energy (E) and frequency factor (A), were 119.22 kJ/mol and 4.67 × 10⁷ (s^?1), respectively. The non-isothermal DSC analyses showed that E and A were 162.12 kJ/mol and 1.32 × 10⁹ (s^?1), respectively, and the reaction order was 0.94. Based on the research work of this paper, it can be said that the cure reaction of DPDPES monomer was of autocatalytic and diffusion-controlled characteristics, and the effect of the diffusion was more evident at low temperature. The cure reaction of DPDPES was a first-order kinetic reaction.     

Synthesis and properties of polyimides containing <Emphasis Type="Italic">N</Emphasis>-substituted benzimidazole rings

A series of novel benzimidazole-containing aromatic polyimides with precise structures in high yields were synthesized by the catalyst-free nucleophilic substitution polycondensation of 4,4’-bis(4-fluorophthalimido) diphenyl ether with different molar ratios of 1,4-bis(2-benzimidazolyl) benzene to 4,4’-dihydroxydiphenyl sulfone via a C–N/C–O coupling reaction process. The reaction was carried out at 210°C in the presence of anhydrous potassium carbonate. The structures of the resulting polymers were characterized by means of FTIR, ¹H NMR spectroscopy, and elemental analysis, and the results were largely consistent with the proposed structure. DSC and TG measurements showed that the polymers had high glass transition temperatures (T_g > 215°C), good thermostability, and high decomposition temperatures (T_d5% > 456°C). These novel polymers also showed easy solubility. In addition, the obtained films have good optical transparency, and the mechanical properties exhibited tension strength of 48.2–74.8 MPa and tensile moduli of 1.3–1.9 GPa without any stretching.     

Synthesis,electrolyte properties and solar cell performance of hyperbranched poly(aryl-ether-urea)s

Hyperbranched poly(aryl-ether-urea)s with phenyl, N,N-dimethylamino ethyl and polyethylene oxide end-groups linked through urethane group – HBPEU-1, HBPEU-2 and HBPEU-3 respectively – were synthesized from an AB₂-type blocked isocyanate monomer and characterized by FT-IR, ¹H-NMR, SEC-MALLS, TGA and DSC techniques. The molecular weight of the polymers were found to be ranged from 4.9 × 10³ ? 1.96 × 10⁴ g/mol. The TGA results showed that the polymers decompose between 175°C – 220°C. In the DSC curves, HBPEU-1 and HBPEU-3 showed T_g at 160°C and 53°C respectively, whereas HBPEU-2 did not showed clear T_g. All the three polymers were converted into polymer electrolytes by doping with LiI/I₂. The doped polymers showed remarkably high ionic conductivity, up to 222 – 277 times compared to the un-doped polymers and the highest conductivity was observed with doped HBPEU-2. The TiO₂ based dye-sensitized solar cells (DSSCs) were fabricated using the doped polymer electrolytes and their performance was tested; HBPEU-2 showed good performance by yielding energy conversion efficiency (η) of 4.5%.     

Synthesis and Characterization of Photosensitive Phosphorus Based Polymers Containing α,β‐Unsaturated Ketones in the Main Chain

1,3‐Bis(4‐hydroxyphenyl)propenone (BHPP) and 3‐(4‐hydroxy‐3‐methoxy phenyl)‐1‐(4‐hydroxyphenyl)propenone (HMPHPP) were used as monomers for preparing photosensitive phosphorus containing polyesters. The photosensitive monomers BHPP and HMPHPP were prepared respectively by refluxing 4‐hydroxybenzaldehyde and 3‐methoxy‐4‐hydroxybenzaldehyde with 4‐hydroxy acetophenone. The polyesters were synthesized by interfacial polycondensation of photosensitive diols with N‐phenylphosphoramidic dichloride using hexadecyltrimethyl ammonium bromide (HDTMAB) as phase‐transfer catalyst. Copolymers were also prepared by incorporating terephthaloyl chloride in the polymer backbone. The synthesized monomers and polymers were characterized by UV, FT‐IR and ¹H, ¹³C and ³¹P‐NMR spectroscopic techniques. The resulting polymers had inherent viscosities in the range of 0.15–0.51 dL/g and showed good solubility in polar organic solvents. The thermal properties of the polymers were studied by thermogravimetric analysis and differential scanning calorimetry under nitrogen atmosphere. The TGA data revealed that the 10% weight loss occurs at 275–320°C and all the synthesized polymers showed high char residues. DSC studies indicate that these polymers possess T_g in the range of 48 to 64°C. The photosensitive property of the polymers in film and solution state was investigated by ultraviolet spectroscopy. The effect of incorporation of terephthaloyl unit on photocrosslinking and thermal properties of the polymers was also studied.     

Structure-property relations in heat resistant polyesters with built-in ether and imide units

A new pyridine-based diacid containing ether and imide units was synthesized via reaction of 5-amino-1-naphthol with 2,6-dichloropyridine in the presence of potassium carbonate in N-methyl-2-pyrrolidone (NMP), and subsequent reaction of the obtained diamine with 2 mol of trimellitic anhydride. A series of poly(ether imide ester)s was synthesized by the polycondensation reactions of the prepared diacid with different diols via high temperature solution polycondensation reaction method. All the products were fully characterized by common spectroscopic methods. The polymers were examined by elemental analysis, IR and ¹H NMR spectra, inherent viscosity, X-ray diffraction, DSC, TGA and DMTA and their properties were studied. Polymers showed high thermal stability and good solubility in polar aprotic solvents. The Structure-property relations of the polymers were also studied.     

Synthesis, curing behavior and thermal properties of fluorene containing benzoxazines

A series of difunctional fluorene-based benzoxazine monomers were synthesized from the reaction of 9,9-bis-(4-hydroxyphenyl)-fluorene with formaldehyde and primary amines including aniline, o-toluidine, n-butylamine, and n-octylamine. Their chemical structures were confirmed by FT-IR, ¹H and ¹³C NMR analyses. The curing behaviors of the precursors were monitored by differential scanning calorimetry (DSC) and FT-IR. The thermal properties of cured polymers were evaluated with DSC and thermogravimetric analysis (TGA). The fluorene-based polybenzoxazines show the typical curing characteristic of oxazine ring-opening for difunctional benzoxazines centred at 231-250 °C, and remarkably higher glass transition temperature and better thermal stability ascribed to the high rigidity, high aromatic content, and intermolecular and intramolecular hydrogen bonding. The thermal decomposition temperature and char yield of aromatic amine-fluorene-based polybenzoxazines are much higher than those of aliphatic amine-based polybenzoxazines.     

New heat stable and processable poly(amide-ether-imide)s derived from 5-(4-trimellitimidophenoxy)-1-trimellitimido naphthalene and various diamines

New aromatic diimide-dicarboxylic acid having flexible ether linkage, 5-(4-trimellitimidophenoxy)-1-trimellitimido naphthalene, was synthesized by the reaction of trimellitic anhydride with 5-(4-aminophenoxy)-1-naphthylamine. Then, a series of novel aromatic poly(amide-ether-imide)s were prepared by the phosphorylation polycondensation of the synthesized monomer with various aromatic diamines. A model compound was synthesized by the reaction of the monomer with aniline. The resulting polymers with inherent viscosities of 0.43-0.70 dl/g were obtained in high yield. All new compounds including the naphthalene-based monomer, model compound, and the resulted polymers were characterized by FT-IR and NMR spectroscopic methods. The ultraviolet λ_max values of the poly(amide-ether-imide)s were also determined. The resulted polymers exhibited a good solubility in a variety of high polar solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), and pyridine. For some of the polymers obtained the crystallinity behavior was estimated by means of wide-angle X-ray diffraction (WXRD) method, and the resulted polymers exhibited nearly an amorphous nature. Thermal stability of the obtained polymers was determined by thermogravimetric analysis (TGA/DTG), and the 10% weight loss temperatures of the one-step degraded poly(amide-ether-imide)s were found to be in the range between 528 and 551 °C in nitrogen. From differential scanning calorimetric (DSC) analyses, the polymers showed T_gs between 276 and 307 °C. Cyclic voltammetry (CV) measurements of a typical polymer showed that they are also electrochemically stable.     

Thermal stability and high glass transition temperature of 4-chloromethyl styrene polymers bearing carbazolyl moieties

A new styrene derivative monomer, 4-(N-carbazolyl)methyl styrene (CzMS), was synthesized by reacting 4-chloromethyl styrene with carbazole in the presence of sodium hydride. Then, CzMS was homopolymerized and copolymerized with different monomers such as methyl methacrylate (MMA), ethyl methacrylate (EMA), methyl acrylate (MA), ethyl acrylate (EA) and n-butyl acrylate (BA) by free radical polymerization method in N,N-di-methylformamide (DMF) solution at 70 ± 1 °C using azobisisobutyronitrile initiator to give the copolymers I-V in good yields. The structure of all the resulted polymers was characterized and confirmed by FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The average molecular weight and glass transition temperature of polymers were determined using gel permeation chromatograph (GPC) and differential scanning calorimeter (DSC) instruments, respectively. It was found that these polymers with carbazole moieties have high thermal stability and the presence of bulk carbazole groups in polymer side chains leads to an increase in the rigidity and glass transition temperature of polymers.     

Studies of silicon-containing maleimide polymers: 1. Synthesis and characteristics of model compounds

A series of the (N-maleimido phenoxy)silane monomers were synthesized by a two-step reaction for using as the application of flame retardant, functional modifier, or a photoresist material in deep-UV region. All of the monomers with maleimide ring were polymerized by radical polymerization in toluene solution using 2,2′-azobisisobutyronitrile (AIBN) as initiator so as to prepare homopolymers. The structures of the maleimide monomers were identified by ¹H, ¹³C, ²⁹Si NMR and element analysis. The chemical structures of polymers were identified by Fourier transform infrared reflection (FT-IR) spectroscopy. The molecular weight distributions of polymers were measured by gel permeation chromatography (GPC) equipment. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to analyze the thermal properties of the polymers. The degree of polymerization in silicon-containing maleimide polymers should be affected by side chains. The introduction of alkylsilane into a side chain of maleimide polymer may reduce the glass transition temperature (T_g) and thermal stability, but increase char yield of solid residue as an excellent flame retardant.     

Synthesis and characterization of side-chain liquid crystalline polymer containing dichroic dye monomer

A series of side-chain liquid crystalline polysiloxanes containing 1-(p-toluidino)-4-anthraquinone undecylenate (TAU) (dye-monomer) and 4-allyloxybenzoyl-4^′-(p-propyl-benzoyl)-p-benzenediol bisate (ABB) (liquid crystalline monomer) side groups were synthesized by copolymeraztion. The molecular structures of the monomers and polymers were confirmed by FT-IR spectroscopy. The optical characterization of the monomer ABB and polymers was made by using polarizing optical microscopy (POM) technique, and their thermal behaviour was investigated by thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC). The conjugate action of the dye (1-(p-toluidino)-4-hydroxyl anthraquinone) and the monomer was analyzed by fluorophotometry. Polymers and monomer ABB revealed nematic phase. And DSC results demonstrated that the glass transition temperatures (T_g) of the polymers increased with the increase in dye-monomer. TGA result showed that the temperatures at which 5% mass loss occurred () for all the polymers were above 270 °C.     

Synthesis,thermal, and photocrosslinking studies of thermotropic liquid crystalline poly(benzylidene‐ether)esters containing α,β‐unsaturated ketone moiety in the main chain

A series of poly(benzylidene‐ether)esters containing a photoreactive benzylidene chromophore in the main chain were synthesized from 2,6‐bis(4‐hydroxy‐3‐methoxybenzylidene)cyclohexanone (BHMBCH) with various aliphatic and aromatic diacid chlorides by an interfacial polycondensation technique. The intrinsic viscosity of the synthesized homo and copolymers determined by Ubbelohde viscometer was found to be 0.12 to 0.17 dL/g. The molecular structure of the monomer and polymers was confirmed by FT‐IR, ¹H NMR, and ¹³C NMR spectral analyses. These polymers were studied for their thermal stability and photochemical properties. Thermal properties were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). It was found that the polymers were stable up to 280 °C and start degrading thereafter. Increase in acid methylene spacer length decreased the thermal stability. The self‐extinguishing property of the synthesized polymers was studied by calculating the limiting oxygen index (LOI) value using a Van Krevelen's equation. The influence of the length of methylene spacer on phase transition was investigated using DSC and odd‐even effect has been observed. Hot‐stage optical polarizing microscopic (HOPM) study showed that most of the polymers exhibited birefringence and opalescence properties. The photolysis of liquid crystalline poly(benzylidene‐ether)esters revealed that α,β‐unsaturated ketone moiety in the main chain dimerises through 2π + 2π cycloaddition reaction to form a cyclobutane derivative and leads to crosslinking. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Terpolymerization of propylene oxide,carbon dioxide,and trimethylene carbonate

High-molecular-weight polymers with different contents of propylene carbonate (PC), and trimethylene carbonate (TMC) units in the polymer chain were synthesized by the coordination anionic copolymerization of carbon dioxide, propylene oxide (PO), and TMC in supercritical carbon dioxide (scCO₂). Zinc adipate (ZnAd) was used as a catalyst. The terpolymerization products were characterized by ¹H and ¹³C NMR, IR spectroscopy, GPC, and DSC. The effect of the reaction conditions on the yield, composition, structure, and molecular weight and thermal characteristics of the terpolymers was studied. The phase behavior of the synthesized polymers and mixtures of polypropylene carbonate with polytrimethylene carbonate was examined.

     

Synthesis of hyperbranched poly(ester urethane isocyanates) and their derivatives

Hyperbranched poly(ester urethanes) containing end isocyanate groups have been synthesized via the reaction of hyperbranched aliphatic polyesterpolydiols of three generations with tolylene diisocyanate. The interaction of these compounds with N,N-dimethylaminoethanol yields their functional derivatives. The polymers are characterized by functional analysis, ¹H NMR and IR spectroscopy, and DSC. It has been demonstrated that the incorporation of urethane moieties leads to development of the microheterogeneous structure of hyperbranched polymers.     

Synthesis, characterization and in vitro degradation study of a novel and rapidly degradable elastomer

Biodegradable elastomers represent a useful class of biomaterials. In this paper, a novel biodegradable elastomer, poly(PEG-co-CA) (PEC), was synthesized by condensation of poly(ethylene glycol) (PEG) and citric acid (CA) under atmospheric pressure without any catalyst. We first synthesized a pre-polymer by carrying out a controlled condensation reaction between PEG and citric acid, and then post-polymerised and simultaneously cross-linked the pre-polymer in the mould at 120 °C. The pre-polymer was characterized by FT-IR, ¹H NMR, ¹³C NMR, GPC and DSC. A series of polymers were prepared at different post-polymerisation time and different monomer ratios. Measurements on the mechanical properties of PEC testified that the new polymers are elastomers with low hardness and big elongation, and hydrolytic degradation of the polymer films in a buffer of pH 7.4 at 37 °C showed that PEC had excellent degradability (all the films show the weight losses more than 60% after 96 h incubation). The different post-polymerisation time and monomer ratio had strong influence on the degradation rates and mechanical performances. The material is expected to be useful for controlled drug delivery and other biomedical applications.