Bio‐Based,Self‐Condensed Polyols

A new method for the synthesis of high‐molar‐mass (MM), bio‐based polyols for elastic polyurethanes is developed. This process is based on the self‐condensation of low MM polyols (M_n ≈ 1000) and vacuum removal of the resulting glycerol. Self‐condensation products are hyperbranched estolide polyols with average MMs close to 3000 and hydroxyl numbers in the range of 40–95 mg KOH g^?1. Three polyols, one with primary and two with secondary hydroxyls and different functionalities, are studied. The transesterification proceeded much faster with primary hydroxyls, leading to high‐viscosity products. The effect of functionality and reactivity of starting polyols on properties is discussed. Practical applications: The process is useful for upgrading the existing natural oil‐based polyols to higher MM, lower OH number and variable‐functionality polyols, for expanding application in the urethane field. The process is simple, involving just an oil‐based polyol, a catalyst, and heating under vacuum.     

Synthesis,characterization and properties of TAP‐6FDA hyperbranched polyimides with different branching degrees

A series of hyperbranched polyimides were successfully synthesized by condensation polymerization of A₂‐type dianhydride monomer 2,2‐bis(3,4‐dicarboxylphenyl) hexafluoropropane dianhydride (6FDA) and B′B₂‐type triamine monomer 2,4,6‐triaminopyrimidine (TAP). Polymers with different branching degrees (DB) and terminated groups were obtained by changing the monomer addition order and the monomer molar ratio. Fourier transform infrared spectroscopy and ¹H NMR were used to verify the structure of the prepared polyimides, which indicated that the amino group still existed in all the products. The DB of the polymers indicated by ¹H NMR increased from 30% to 79% with the molar ratio of TAP:6FDA decreasing from 1:1 to 1:2. The absolute molecular weights were measured by size‐exclusion chromatography with multi‐angle laser light‐scattering detection, which suggested that the highest molecular weight would be obtained when the molar ratio of amino groups:anhydride groups of the monomers was 3:3.2. With the DB increasing, the d‐spacing values indicated by wide angle X‐ray diffraction increased from 5.15 Å to 5.68 Å and the UV ? visible spectra of the polymers exhibited decreasing cut‐off wavelengths. The 5% weight loss temperature in nitrogen increased with decreasing content of TAP monomer, and the glass transition temperatures of the obtained polyimides decreased from 282 °C to 258 °C with increasing DB. © 2013 Society of Chemical Industry     

Rheological properties of hydroxyl‐terminated and end‐capped aliphatic hyperbranched polyesters

The rheological behavior of two series of aliphatic hyperbranched (HB) polyesters, based on 2,2‐bis(hydroxymethyl)propionic acid (bis‐MPA) and di‐trimethylol propane (Di‐TMP) as a tetrafunctional core, was studied. The effect of the size (pseudo‐generation number, from second to eight) and structure on the melt rheological properties was investigated for a series of hydroxyl‐terminated HB polyesters. In addition, the influence of the nature and degree of modification of the terminal OH groups in a series of fourth‐generation polyesters end‐capped with short and long alkyl chains and some aryl groups on the rheological properties was analyzed. The time–temperature superposition procedure was applied for the construction of master curves and for the analysis of the rheological properties of HB polyesters. The data obtained from WLF analysis of the HB polyesters showed that the values of the thermal coefficient of expansion of free volume α_f and the fractional free volume at the glass transition temperature, f_g, increase with increasing size of the HB polyesters. It was shown that the modified HB polyesters exhibited lower T_g and T_G′=G″ temperatures, above which viscous became dominant over elastic behavior. From an analysis of the master curves of the modified HB polyesters, it was observed that with increasing degree of modification, both storage and loss modules and complex dynamic viscosity and apparent energy for viscoelastic relaxation decrease, because of reduced intermolecular hydrogen interactions. They do not exhibit a plateau of rubbery behavior, which confirms that no entanglements are present and that the molar masses are below the critical molar mass. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41479.     

Synthesis of hyperbranched polyester‐amides and their application as crosslinkers for polyurethane curing systems

A series of hyperbranched polyester‐amides (S1, S2, S3) with trimethylolpropane as a core molecule were synthesized using core‐dilution/slow monomer addition strategy. The products were characterized by FTIR, ¹³C NMR, GPC, TGA, hydroxyl value measurement, and viscosity measurement. The result showed that the hyperbranched polyester‐amides synthesized had narrow molecular weight distribution and high degree of branching (DB). The hyperbranched polyester‐amides synthesized were used as crosslinkers for polyurethane curing systems and the mechanical properties of the polyurethane curing systems were investigated. It was found that the best tensile property and tear strength were obtained when the S2 were used as crosslinkers and the molar ratio of  OH and  NCO was 1 : 1. It was also found that the polyurethane curing systems had the highest hardness and T_g when the S3 were used as crosslinkers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of epoxy‐ended hyperbranched polymers with precisely controllable degree of branching by thiol‐ene Michael addition

Epoxy‐ended hyperbranched polymers (EHPs) have a wide range of applications due to their outstanding performances. Because their microstructures are not positively identified, it is very difficult to ascertain the reinforcing and toughening mechanisms of EHPs and their interface interaction with other matrixes. Controllable synthesis of EHPs with precise degree of branching (DB) remains to be a major challenge. Here, a method for preparing novel nitrogen‐phosphor skeleton epoxy‐ended hyperbranched polymers (NPEHP) with controllable DB by a thiol‐ene Michael addition between thiol‐ended hyperbranched polymers (NPHSH) and glycidyl methacrylate have been firstly reported. NPHSH is synthesized by an esterification between hydroxyl‐ended hyperbranched polymers (NPHOH) and 3‐mercaptopropionic acid. NPHOH is prepared by a thiol‐ene Michael addition between methacrylate group of a monomer and thiol group of linear monomer (AB) and/or branched monomer (AB₂). The molar ratio between the AB and AB₂ monomers controls the DB of the products. The ¹H NMR spectra analysis of NPHOH shows that their experimentally determined DBs are very close to their theoretical values, indicating good controllability of their DBs. The narrow molecular weight distributions of NPHOH, NPHSH, and NPEHP suggest high efficiency of the thiol‐ene Michael addition. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44277.     

Synthesis and properties of novel hyperbranched polyimides end‐capped with metallophthalocyanines

A fluorinated hyperbranched polyimide (HBPI) is synthesized by using a triamine monomer, 1,3,5‐tris(2‐trifluoromethyl‐4‐aminophenoxy)benzene (TFAPOB) (B₃), as a “core” molecule, 4,4′‐oxydiphthalic anhydride (ODPA) as a A₂ monomer, and 4‐aminophthalonitrile as an end‐capping reagent. After that, a series of novel fluorinated hyperbranched polyimides end‐capped with metallophthalocyanines were prepared by the reactions of dicyanophenyl end‐capped hyperbranched polyimide with excessive amounts of 1,2‐dicyanobenzene and the corresponding metal salt in quinoline. The resulting polyimides containing metallophthalocyanine unites shows optical absorption in the visible region. The absorption bands of the polymers in chloroform solution are in the range of 665–701 nm. These polyimides show glass transition temperatures between 216 and 225°C, and the 5 wt % weight loss temperature of the polymers varied from 440 to 543°C under nitrogen. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and self‐assembly of hyperbranched polyethers peripherally modified with adenosine 5′‐monophosphate

The chloride functionalized hyperbranched poly(3‐ethyl‐3‐oxetanemethanol) (HBPO) was prepared via reaction of thionyl chloride with hydroxyl groups. Adenosine 5′‐monophosphate (AMP) groups were attached to HBPO in CH₂Cl₂ in the presence of triethylamine (TEA) as an acceptor of HCl. The self‐assembly of resultant hyperbranched molecules bearing self‐complementary hydrogen‐bonding patterns would allow the generation of a highly organized supramolecular architecture in a selected solvent. The morphologies of self‐assembly structures were depended on the level of AMP in polymer and the concentration in solvent. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1147–1152, 2006     

Hyperbranched polymer for light‐emitting applications

A light‐emitting partially conjugated hyperbranched polymer (2,5‐dimethoxy‐substituted hyperbranched poly(p‐phenylene vinylene), MOHPV) based on rigid fluorescent conjugated segments, 2,5‐dimethoxy‐substituted distyrylbenzene (a derivative of oligo‐poly(p‐phenylene vinylene)), and flexible non‐conjugated spacers, trioxymethylpropane, was synthesized via an A₂ + B₃ approach. The weight‐average molecular weight was 2.48 × 10⁴ g mol^?1. The introduction of two methoxy groups into central rings of the oligo‐poly(p‐phenylene vinylene) imparted to MOHPV better solubility in common organic solvents and processability than its analogues reported in our previous work, especially the fully conjugated hyperbranched polymers. The effect of the molar ratio of monomer A₂ to monomer B₃ on the molecular weight and molecular weight distribution was investigated. A single‐layer light‐emitting diode was fabricated employing MOHPV as an emitter. A double‐layer light‐emitting diode was also fabricated by doping an electron transport material, 2‐(4‐biphenylyl)‐5‐phenyl‐1,3,4‐oxadiazole, into the emitting layer and inserting a thin layer of tri(8‐hydroxyquinoline)aluminium as electron‐transporting/hole‐blocking layer. A maximum luminance of 1500 cd m^?2 at 12 V and a maximum electroluminescence efficiency of 1.38 cd A^?1 at 14 mA cm^?3, which are approximately 43.5 and 12.9 times greater, respectively, than those of the single‐layer device, were achieved. The synthetic simplicity, excellent solubility and solution processability, and less of a propensity to aggregation make MOHPV a novel type of emitter for polymer light‐emitting displays. Copyright © 2010 Society of Chemical Industry     

Preparation of star polymers of hyperbranched polyglycerol core with multiarms of PS‐b‐PtBA and PS‐b‐PAA

Atom transfer radical polymerization (ATRP) was applied to synthesize a new kind of star polymers of hyperbranched polyglycerol (HPG) core with multiarms of PS‐b‐PtBA and PS‐b‐PAA by using the “core first” technique. The HPG core was obtained by anionic polymerization of glycerol first, and then the pendant hydroxyl groups of HPG were esterified with 2‐bromoisobutyryl bromide to yield the HPG‐g‐Br, which was used as macroinitiator for ATRP of the first monomer (St) and then second monomer (tBA). After hydrolysis of the PtBA block, poly(acrylic acid) (PAA) side chains were formed. The final products and intermediates were characterized by GPC, NMR, and FTIR in detail. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and Characterization of the Nitrogen‐Rich Hyperbranched Polymers – Poly([1,2,3]‐Triazole‐[1,3,5]‐Triazine)s

Novel hyperbranched poly([1,2,3]‐triazole‐[1,3,5]‐triazine)s (HBP TT) were synthesized by a 1,3‐dipolar cycloaddition reaction from AB₂ monomer – 2‐azido‐4,6‐bis‐prop‐2‐yn‐1‐yloxy‐ [1,3,5]‐triazine (ABPOT). The monomer contains one azide group A and two terminal alkyne units B. Thermal polymerization of ABPOT in bulk or in DMF solution leads to hyperbranched polymers containing both 1,4‐ and 1,5‐disubstituted [1,2,3]‐triazoles. The monomer was also polymerized catalytically in the presence of Cu(I) salts under mild reaction conditions in DMSO solution and in bulk affording hyperbranched poly‐[1,2,3]‐triazoles 1,4‐disubstituted only. The reactions lead to the products soluble in aprotic polar solvents like DMSO or DMF. Side reactions can proceed in a few cases, particularly: (i) homocoupling of alkyne groups, leading to the formation of insoluble products as a result of cross‐linking, (ii) isomerization of propynyloxytriazine fragments to propynyl‐ or propadienyltriazinone ones, and (iii) hydrolysis of triple bonds without the loss of solubility. Heats of formation of monomer and synthesized polymers were calculated from their combustion heats. All products were characterized by NMR‐, IR‐spectroscopy, and size exclusion chromatography (SEC) data. The obtained results open the prospect for the use of HBP TT as the high‐enthalpy modifiers for energetic and non‐energetic binders.     

Synthesis and characterization of biodegradable linear–hyperbranched barbell‐like poly(ethylene glycol)‐supported poly(lactic‐ran‐glycolic acid) copolymers through direct polycondensation

A series of biodegradable linear–hyperbranched barbell‐like poly(ethylene glycol) (PEG)‐supported poly(lactic‐ran‐glycolic acid) (PLGA) copolymers were synthesized with PEG, d ,l ‐lactic acid aqueous solution, glycolic acid and gluconic acid (Glu) under bulk conditions. The branching density of the hyperbranched section was varied by controlling the molar ratio of Glu to hydroxyl‐terminal groups of PEG ([Glu]/[OH] = 1, 3.5, 6.0, 8.5). Chemical structures of these copolymers were confirmed using NMR spectroscopy. The molecular weights were determined using ¹H NMR group analysis and gel permeation chromatography, both results being consistent with one another. The results of hydrolytic degradation indicate that these copolymers can degrade completely in no more than three weeks. The thermal properties were evaluated using differential scanning calorimetry and thermogravimetric analysis. The results indicate that the glass transition temperatures and melt temperatures of these copolymers are not above 50 °C. The self‐assembly behavior of the copolymers on hydrophilic surfaces was also investigated. The morphology of self‐assembly films made of the copolymers was observed using atomic force microscopy, and the results indicate that these copolymers exhibit more inhomogeneous and rough structural orientated films on a silicon wafer substrate with increasing branching densities. Due to the favorable biodegradability and biocompatibility of the PLGA and PEG, the results suggest new possibilities for these novel structural amphiphilic linear–hyperbranched barbell‐like copolymers as potential biomaterials. © 2013 Society of Chemical Industry     

Gas permeability of fluorinated hyperbranched polyimide

The gas permeability of carbon dioxide, oxygen and nitrogen for hyperbranched polyimide (HBPI) containing trifluoromethyl groups were investigated. The HBPIs were prepared by condensation polymerization of a triamine monomer, 1,3,5‐tris(2‐trifluoromethyl‐4‐aminophenoxy) benzene (TFAPOB) and a commercially available dianhydride monomer 1,4‐bis(3,4‐dicarboxyphenoxy) benzene dianhydride (HQDPA). With different monomer addition methods and different monomer molar ratios, amine terminated HBPI (AM‐HQDPA) and anhydride terminated HBPI (AD‐HQDPA) were obtained, subsequently, the trifluoromethylphenyl amine terminated HBPI (CF₃‐HQDPA) was achieved by modifying the end groups of AD‐HQDPA with (3,5‐ditrifluoromethyl)aniline. The CF₃‐HQDPA exhibited a good mechanical and thermal stability as well as AM‐HQDPA, and showed better gas permeabilities than that of AM‐HQDPA because of increase of free volume contributed by the bulky trifluoromethyl group introduced, but, the selectivity ofCF₃‐HQDPA was lower than that of AM‐HQDPA. This result was consistent with the trade‐off relationship. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Novel redox‐active polycarbazole‐functionalized polycatechol network films produced by controlled electropolymerization

A novel precursor, 1,2‐bis[6‐(9H‐carbazol‐9‐yl)hexyloxy] benzene (BCHB), was successfully synthesized. Its polycarbazole‐functionalized polycatechol network films, poly{1,2‐bis[6‐(9H‐carbazol‐9‐yl)hexyloxy] benzene} (PBCHB), with good redox activity were formed by the direct anodic oxidation of BCHB in CH₂Cl₂ and boron trifluoride diethyl etherate binary solvent solution. Ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, ¹H‐NMR, and matrix‐assisted laser desorption ionization–time of flight mass spectrometry were used to characterize the polymers. The results indicate that the network polymers could be synthesized electrochemically with different polymerized units by controlled electropolymerization. The PBCHB films prepared at low potential were oligomers with short conjugation lengths and were soluble in common organic solvents, whereas the polymers with long conjugation lengths and hyperbranched network structures obtained at high potential were insoluble. The electrosynthesized polymers exhibited blue emission maxima around 450 nm and were much more redshifted than their monomer. The emissions were also brighter; this indicated the polymers are potential good blue‐light emitters. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of alternate copolymers constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments

1,3‐Dichloro‐1,1,3,3‐tetraphenyldisilazane (DCTPS) with 71.6% yield was synthesized by the reaction of hexaphenylcyclotrisilazane (HPCT) with Ph₂SiCl₂ catalyzed by dibutyltin dilaurate. A ring‐closure reaction of DCTPS was carried out with BuLi in xylene–hexane mixture solvent; 1,3‐bis(chlorodiphenylsilyl)‐2,2,4,4‐tetraphenyl‐cyclodisilazane (BcPTPC) with 73.2% yield was obtained. Hydrolysis of BcPTPC in ether–triethylamine solvent resulted in 71.9% yield of 1,3‐bis(diphenylhydroxysilyl)‐2,2,4,4‐tetraphenylcyclodisilazane (B_HPTPC). By condensation polymerization of B_HPTPC with α,ω‐bis(diethylamino)‐oligo‐dimethylsiloxane, a kind of alternate copolymer constructed by 1,3‐bis(diphenylsilyl)‐2,2,4,4‐tetraphenylcyclodisilazane units with oligo‐dimethylsiloxane segments [P(BPTPC‐alt‐ODMS)] was synthesized. BcPTPC, B_HPTPC as well as P(BPTPC‐alt‐ODMS) were characterized by ²⁹Si‐NMR spectra, FT‐IR spectra, and elemental analysis. DGA study shows that P(BPTPC‐alt‐ODMS)s are thermally stable. The thermal decomposition onsets of P(BPTPC‐alt‐ODMS)s are all above 520°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1484–1490, 2005     

Synthesis and application of water‐soluble hyperbranched poly(ester)s from maleic anhydride and glycerol

A water‐soluble hyperbranched polyester with a considerable number of hydroxyl terminal groups was synthesized by reacting maleic anhydride and glycerol in the absence of a solvent. The synthesized intermediate product was converted to the hyperbranched polyester by condensation polymerization, and the water by‐product produced during the esterification reaction may be removed by vacuum distillation. In the synthesis process, the crosslinking reaction occurs readily if maleic anhydride is in excess. The result shows that the product synthesized by this one‐step method is insoluble in water at room temperature, whereas the product of a quasi one‐step method, in which pentaerythritol was added as a core molecule, has good water solubility when pentaerythritol and the raw material have a molar ratio of 1 : 100 or 1 : 150. The resulting hyperbranched polyester was purified by column chromatography and characterized by infrared spectrometry. The synthetic hyperbranched polyester was used at 0.5% as a crosslinking agent for acrylic ester to inform acrylic ester latex film; the water absorption of the film was decreased significantly, the viscosity was increased, and some mechanical properties were improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of commercial aliphatic hyperbranched polyesters

Commercially available Boltorn Hx (x=20, 30) hyperbranched (HB) polyesters of different theoretical core/monomer ratio (1/12 for H20 and 1/28 for H30) were characterized with respect to molar mass, composition, and structure. The results were compared to those obtained for the Boltorn H40 with a core/monomer ratio of 1/60 [?agar E, ?igon M. Macromolecules 2002;35:9913 [11]]. The main side reaction in the pseudo one-pot synthesis of Boltorn polymers is a self-condensation of bis-MPA leading to the formation of HB structures without a core molecule. These are actually branches containing an unreacted carboxyl group. The fraction of HB structures without a core molecule increases with decreasing core/monomer ratio due to the decreasing fraction of HB structures with a core molecule. Since HB structures without a core molecule are of lower molar masses than HB structures with a core molecule, they particularly decrease the number average molar masses of the samples compared to the theoretically calculated ones. The polydispersity of Boltorn Hx increases with decreasing core/monomer ratio. Some of the hydroxyl groups were found to react intramoleculary forming ether bonds. Boltorn Hx polyesters have low degrees of branching due to the limited carboxyl group conversions, low DP_n values, the presence of the core unit, and lower reactivity of hydroxyl groups in linear repeat units compared to those in terminal ones. The degree of branching according to Frey increases with decreasing core/monomer ratio.     

Investigation of readily processable thermoplastic‐toughened thermosets. V. Epoxy resin toughened with hyperbranched polyester

This article describes the use of hyperbranched polyester oligomers (HBPs) as modifiers for epoxy thermosets. The effect of HBP molar mass, end group, and loading on prepolymer viscosity, thermoset fracture toughness, T_g, and high‐temperature dynamic storage modulus (E′) were measured. The HBP molar mass was systematically increased from nominal values of ∼ 1750 g mol (Generation 2, or G2) up to ∼ 14,000 g mol (Generation 5, or G5), which corresponds from a low of two layers of monomer up to a maximum of five layers of monomer around the central core. Toughness increased only modestly with the molar mass of the HBP. At 7% loading in the epoxy thermoset, the G5 HBP increased toughness by ∼ 60% over the untoughened control. Toughness increased to 82% above the untoughened control at a loading of 19% G5 HBP, but the toughness decreased at 28% HBP loading. The T_g and E′ were influenced by the HBP modifier, but the effect was not systematic and may have been due to competing effects of HBP molar mass and end group. The effect of the architecture of the thermoplastic modifier was investigated by introducing a linear aliphatic polyester (∼ 5400 g mol) with a repeat unit structure, which was similar to that of the HBP. At the molecular weight range investigated, neither the prepolymer viscosity nor the thermoset toughness of the HBP–epoxy was significantly different from that of the linear polyester in epoxy. Preliminary results are presented showing the effect of thermoplastic molecular weight and architecture on morphology. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 151–163, 1999     

Thermomechanical and water‐responsive shape memory properties of carbon nanotubes‐reinforced hyperbranched polyurethane composites

Shape memory composites of hyperbranched polyurethane (HBPU) and acid‐treated multi‐walled carbon nanotubes (MWNTs) were prepared using an in situ polymerization method. HBPUs with different hard segments contents were synthesized via the A₂ + B₃ approach using poly(ethylene glycol) (PEG) as a soft segment, 4,4′‐methylene bis(phenylisocynate), castor oil, and 1,4‐butanediol as hard segment. Compared to HBPU, the HBPU/MWNT composites showed faster shape recovery and double the shape recovery stress in the thermomechanical shape memory test, which was dependent on the MWNTs content and HBPU hard segment content. The water‐responsive shape memory effect of HBPU/MWNT composites was considered to result from the combined contribution of hydrophilic PEG and well dispersed MWNTs in highly branched HBPU molecules. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Hyperbranched polyesters with carboxylic acid functional groups for the inhibition of the calcium carbonate scale

Scale deposits exist widely in industrial water‐cooling systems and oil‐production systems, causing severe damage to the equipment. The most effective way to prevent the formation of scale has been to use an inhibitor. The use of a hyperbranched polymer as an inhibitor, however, has rarely been reported. In this study, we prepared a hydroxyl‐terminated hyperbranched polyester (HBPE–OH) with trimethyloypropane as the core and 2,2‐bis(hydroxymethyl)propionic acid as an AB₂ monomer. The HBPE–OH was then modified with succinic anhydride to obtain the carboxyl‐terminated hyperbranched polyester (HBPE–COOH). The effects of the dosage, Ca²⁺ concentration, pH value, and temperature of the system on the inhibition efficiency were investigated when HBPE–COOH was used as an inhibitor of calcium carbonate (CaCO₃) scale. HBPE–COOH acted as a good antiscaling inhibitor for CaCO₃; when the polyester concentration was 200 mg/L, the scale inhibition rate exceeded 70%. Scanning electron microscopy and X‐ray powder diffraction demonstrated that the mechanism of inhibition was the disturbance of the growth of the crystals and modification of the crystal morphology by the hyperbranched polyester. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46292.     

Synthesis of s‐triazine‐based hyperbranched polyurethane for novel carbon‐nanotube‐dispersed nanocomposites

s‐Triazine‐based hyperbranched polyurethanes (HBPUs) with different hard segments were synthesized by A₂ + B₃ approach. Various kinds of multiwalled carbon nanotube (MWNT) nanocomposites with HBPU were prepared to investigate an impact of hyperbranched polymer on dispersion of MWNTs in the polymer matrix and the resulting properties of nanocomposites. Synthesized HBPUs were characterized using FTIR and NMR measurements. The highly branched structures were found very effective in enhancing the pristine MWNT dispersion in the polymer matrix. As a result, the MWNT‐reinforced HBPU nanocomposites showed a steep increase in the yield stress and modulus and enhanced shape memory effect with an increase of hard segment and MWNT loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010