Synthesis and self-assembly of hyperbranched polyester peripherally modified by touluene-4-sulfonyl groups

In this paper, hyperbranched polyesters (HPs) were synthesized in the molten state from 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) and 2-ethyl-2-hydroxymethyl-1,3-propanediol (TMP) using acid catalysis. The modified hyperbranched polyesters were obtained through the chemical modification of the hyperbranched polyester cores by substituting a controlled fraction of the terminal hydroxyl groups with touluene-4-sulfonyl chloride using triethylamine (TEA) as an acceptor of HCl. The resultant polyesters were characterized by ¹H NMR, ¹³C NMR, FT-IR, UV and GPC and their self-assembly behaviors were investigated. The results revealed that self-assembled structures could be formed in selected solvents (trichloromethane/acetone or trichloromethane/n-hexane).     

Synthesis, optical and electrochemical properties of new hyperbranched poly(triphenylamine amide)s

A new triphenylamine-containing AB₂ type monomer with one carboxylic acid and two amino groups, 4-(bis(4-aminophenyl)amino)benzoic acid (3), was synthesized and used for the preparation of hyperbranched poly(triphenylamine amide)s. The self-polycondensation of the AB₂ monomer (3) afforded hyperbranched poly(triphenylamine amide) with amino end groups. The molecular weight of the hyperbranched poly(triphenylamine amide) was 21,000 Da determined by light scattering. End-capped hyperbranched polyamides were isolated by the chemical modification of unreacted amino groups with various acid chlorides. All the hyperbranched poly(triphenylamine amide)s exhibit excellent solubility in organic solvents such as NMP, DMF, DMSO, and DMAc at room temperature. The viscosities of hyperbranched poly(triphenylamine amide)s are as low as about 0.15 dL/g due to their dendritic structures. Poly(triphenylamine amide)s end-capped with rigid benzene ring have higher thermal stability than those with amino or aliphatic end groups. The photoluminescence of the hyperbranched polyamides is blue-yellow emissions around 430-510 nm. The energy gaps of the hyperbranched poly(triphenylamine amide)s with different end groups are about 2.93 eV and are independent on the end groups, but the HOMO and LUMO energy levels are dependent on the end groups.     

Hyperbranched polymers from divinylbenzene and 1,3-diisopropenylbenzene through anionic self-condensing vinyl polymerization

Hyperbranched polymers were synthesized using anionic self-condensing vinyl polymerization (ASCVP) by forming ‘inimer’ (initiator within a monomer) in situ from divinylbenzene (DVB) and 1,3-diisopropenylbenzene (DIPB) using anionic initiators in THF at −40 °C. The reaction of equimolar amounts of DVB and nBuLi results in the formation of hyperbranched poly(divinylbenzene) through self-condensing vinyl polymerization (SCVP). The hyperbranched polymers were invariably contaminated with small amount of gel (<15%). No gelation was observed when using DIBP with anionic initiators. The presence of monomer-polymer equilibrium in the SCVP of DIPB restricts the growth of hyperbranched poly(DIPB). The inimer synthesized from DIPB at 35 °C undergoes intermolecular self-condensation to different extent depending on the nature of anionic initiator at −40 °C. The molecular weight of the hyperbranched polymers was higher when DPHLi was used as initiator. A small amount of styrene ([styrene]/[Li⁺]=1) was used to promote the chain growth by inducing cross-over reaction with styrene, and subsequent reaction of styryl anion with isopropenyl groups of inimer/hyperbranched oligomer. The hyperbranched polymers were soluble in organic solvents and exhibited broad molecular weight distribution (2<M_w/M_n<17).     

New hyperbranched polymers containing second-order nonlinear optical chromophores: Synthesis and nonlinear optical characterization

Three hyperbranched polymers (P1-P3) containing second-order nonlinear optical chromophores were synthesized by copolymerization of aromatic dialdehydes (carbazole, triphenylamine or benzene moieties) with sulfonyl-based chromophores attached with three active methylene groups, from “A₂ + B₃” approach based on simple Knoevenagel reaction. For comparison, their corresponding linear analogue polymers (P4-P6) were prepared. All the polymers are soluble in common organic solvents, and exhibit good thermal stability. The tested NLO properties of the hyperbranched polymers are better than their corresponding linear polymers, due to the three-dimensional spatial separation of the chromophores in the obtained hyperbranched polymeric structures.     

超支化聚合物的溶液相行为与涂料应用

通过新的合成方法相继制备超支化聚酯、聚醚、聚酯酰胺及聚丙烯酸酯等,其结构越来越复杂,应用也越来越广泛.本文概述了超支化聚合物椭球型的结构特征和无序支化到可控的制备方法的发展.重点介绍了其溶液无链缠绕的流变特性和相行为研究进展,通过末端官能团的改性可改变超支化聚合物的溶解性、流变性和功能化.对其在涂料领域的应用如固化剂、...     

Synthesis and Demulsification of Two Lower Generation Hyperbranched Polyether Surfactants

A lower generation hyperbranched molecular skeleton R₁₂-1.0G was synthesized with methanol as solvent by means of Michael addition and amidation condensation reaction with C₁₂ fatty amine, acrylate, and ethylenediamine as raw materials. The structure was characterized by IR and ¹H NMR spectrum. Two lower generation hyperbranched polyethers were further synthesized by means of a skeleton as raw materials through addition reaction with epoxyethane and epoxypropare, respectively. The surface tension, cloud point, and HLB value of the hyperbranched polyethers were determined systematically. On this basis, the demulsification of two hyperbranched polyethers for simulated emulsion was studied in this paper. The results showed that two hyperbranched polyethers are typical surfactants, and they show different demulsification for the simulated emulsion. The structure of polyethers can influence the demulsification performance, and the main factor is the molecular block structure. The demulsification mechanism of two hyperbranched polyethers was studied using the single-droplet protocol, and the dynamic data of drainage time, half life time, and rupture rate constant obtained are consistent with the demulsification law of the hyperbranched polyethers. This study may be helpful in accounting for the demulsification mechanism and for developing effective demulsifiers with new structure.     

Reactive core/shell type hyperbranched blockcopolyethers as new liquid rubbers for epoxy toughening

Novel reactive core/shell-type hyperbranched blockcopolyethers were tailored as new class of liquid rubbers useful as flexibilizers and toughening agents of anhydride-cured epoxy resins. Anionic ring-opening polymerization of glycidol onto a six-arm star poly(propylene oxide-block-ethylene oxide) afforded hyperbranched polyether cores as macroinitiators for propylene oxide graft copolymerization. The hydroxy end groups of the resulting polyether-polyols have been modified in order to prepare stearate, hydroxy benzoate and epoxy derivatives. The modification afforded reactivity and polarity design which has been the key to improved blend performance with epoxy resins. In comparison to conventional hyperbranched epoxy-terminated polyesters, the influence of molecular architectures on thermal, mechanical and morphological properties of hexahydrophthalic acid anhydride-cured bisphenol-A diglycidylether was examined. As a function of polarity and reactivity design, it was possible to control phase separation and to vary mechanical properties from highly flexible to stiff and tough.     

Synthesis and characterization of hyperbranched photosensitive polysiloxane urethane acrylate

A novel hyperbranched photosensitive polysiloxane urethane acrylate (HBPSUA) based on hyperbranched polyesters (HBP-OH) has been synthesized. HBP-OH was synthesized from N,N-diethylol-3-amine methylpropionate as AB₂ monomer and trimethylolpropane (TMP) as a core molecule. The structure of the oligomer was characterized by FTIR, GPC and ¹H NMR. The molecular weight of the oligomer is about 10,000 and the viscosity is 4446 cps at room temperature. The HBPSUA possesses good compatibility with most of acrylate monomers. The effect of photoinitiators, monomers and light intensity on the photopolymerization kinetics of the oligomer HBPSUA was investigated by real-time infrared spectroscopy (RT-IR). The results show that HBPSUA can well photopolymerize under UV-irradiation in the presence of photoinitiators. Irgacure 1700 showed the highest initiating efficiency among those tested photoinitiators. The optimal concentration of photoinitiator (Darocur 1173) is determined as 0.05 wt.%. The system of HBPSUA/TPGDA has the high conversion of double bond and polymerization rate, and they are 92.38% and 22.25 s⁻¹, respectively. Compared with linear systems (PSUA), HBPSUA has the higher photopolymerization rate and lower viscosity. The cured film of HBPSUA possesses good flexibility.     

Facile synthesis, high thermal stability, and unique optical properties of hyperbranched polyarylenes

New hyperbranched polyarylenes of high molecular weights are synthesized in high yields by copolycyclotrimerizations of diynes 1,4-diethynylbenzene, 4,4′-diethynylbiphenyl, 2,7-diethynylfluorene and 2,5-diethynylthiophene with monoynes 1-heptyne, 1-octyne and 1-dodecyne catalyzed by TaCl₅-Ph₄Sn in toluene. All the polymers show good solubility in common organic solvents, possess excellent thermal stability, and emit strong deep-blue lights of ∼400 nm with quantum efficiencies up to 98%. The polyarylenes effectively limit 532 nm lasers light, some of which show optical limiting performances superior to that of C₆₀, a well-known optical limiter.     

Mechanical and thermal properties of UV cured mixtures of linear and hyperbranched urethane acrylates

The properties of urethane acrylate resin mixtures based on the linear and hyperbranched aliphatic polyesters were examined. Linear polyester was synthesized from neopentil glycol and adipic acid. Hyperbranched polyester of the third generation was synthesized from 2,2-bis(hydroxymethyl)propionic acid and di-trimethylol propane. The modification of 60% of hyperbranched aliphatic polyester OH end groups was carried out with isononanoic acid or with soybean fatty acids. Two hyperbranched urethane acrylates, with the same degree of acrylation, and one linear urethane acrylate were obtained by reaction of appropriate polyester and isophorone diisocyanate and 2-hydroxyethyl acrylate. The influence of added amount of HUA and nature of non-acrylic end groups on the rheological, mechanical and thermal properties of the uncured and UV cured mixtures diluted with 20 wt.% hexanediol diacrylate was examined. The nature of non-acrylic end groups have great effect on the interaction between linear and hyperbranched urethane acrylates, which further has a crucial influence on the examined properties of uncured and UV cured mixture samples.     

Synthesis of hyperbranched polythiophenes containing tetrachloroperylene bisimide as bridging moiety for polymer solar cells

The goal of this research is to synthesize the hyperbranched polythiophene derivatives (P1 and P4) containing tetrachloroperylene bisimide as bridging moiety for investigation of thermal, electrochemical, and opto-electrical properties of these derivatives. The polymers (P2 and P3) containing soft alkyl spacer as bridging moiety and linear poly(3-hexylthiophene) (P3HT) were also synthesized for comparison in this study. Polymers with high regioregularity were synthesized via the Universal Grignard metathesis polymerization. The GPC results showed that molecular weights of hyperbranched polythiophenes are higher than that of P3HT. The TGA experiments revealed a first-stage weight loss at about 300 °C for all polymers; besides, polymers containing rigid tetrachloroperylene bisimide groups possess less weight loss than P3HT after heating, indicative of enhanced thermal stabilities. The UV–vis absorption maxima of hyperbranched polymers are similar to that of P3HT in film state, while their absorption shoulder bands are stronger than that of P3HT, indicating stronger interchain interaction and shorter distance between backbones by the introduction of bridge architecture. Moreover, an attenuation of fluorescent intensity was found for those hyperbranched polymers, implying reduced recombination of excitons to emit light and more opportunity for carriers to migrate to both electrodes. Electrochemical analysis showed that introducing hyperbranched structure resulted in decreasing both LUMO and HOMO levels of polymers. All polymers were used for fabrication of polymer solar cells with the configuration of ITO/PEDOT/polymer:PC₆₀BM (1:2 w/w)/LiF/Al to evaluate their performance. The power conversion efficiency (PCE) of the P3HT:PC₆₀BM-based device is 0.54%, while devices based on hyperbranched polymers showed PCE values in the range of 0.45–0.84%. The morphological study of polymer:PC₆₀BM blend films was performed by AFM for interpretation of efficiency trend of devices.     

Hyperbranched poly(ether-siloxane) amphiphiles of surprisingly high solubility in supercritical carbon dioxide

In this work, we present a simple method for preparation of an inexpensive CO₂-philic amphiphiles for solubilization and related applications. The poly(ether-siloxane)s we have synthesized showed very good solubility in supercritical carbon dioxide, despite the fact they contained hydrophilic polyether structures. So far, incorporation of any type of substituents to the poly(dimethylsiloxane) (PDMS) chains resulted in decrease of the solubility in scCO₂. We showed that, it is possible to obtain copolymers containing both hydrophilic (polyether) and hydrophobic (polysiloxane) parts which have better solubility in scCO₂ than respective homopolymers. The proposed synthetic route should allow the design of a wide range of related CO₂-philic hyperbranched materials.     

Physical and thermal properties of UV curable waterborne polyurethane dispersions incorporating hyperbranched aliphatic polyester of varying generation number

Three series of novel waterborne hyperbranched polyurethane acrylates for UV curable aqueous dispersions (WHPUD) based on hydroxy-functionalized hyperbranched aliphatic polyesters Boltorn™ of varying generation number were investigated. The effects of the overall composition, including acidic and acrylate groups, and functionality of hyperbranched polyester were studied in terms of particle size, rheology, photopolymerization kinetics, dynamic mechanical thermal as well as thermal degradation behaviors of WHPUDs. The average particle sizes of aqueous dispersions, 43-134 nm, were determined by laser light scattering. The stability and particle size were dependent on the amount of carboxylic acid groups, degree of neutralization, and molecular structure. The rheological features have revealed that all dispersions belong to pseudoplastic fluids. The shear thinning behavior of WHPUDs is more pronounced for lower generation of hyperbranched polyester. The photopolymerization rates of the resins under UV irradiation in the presence of a photoinitiator showed an increasing trend with higher functionality of acrylate. The glass transition temperature (T_g) of UV cured films evaluated by dynamic mechanical thermal analysis (DMTA) showed that the influence of end capping by hard segment consisting of IPDI-HEA is remarkable due to the increase of crosslink density. The T_g, storage modulus and loss modulus increased with increasing generation number from the second to the fourth. The results of TGA for cured WHPUD films indicated good thermal stability with no appreciable weight loss until 200 °C, and that an increase in the hard segment content provoked the increases in thermal degradation temperature. This behavior is rationalized by relating crosslink density dependence of chain end concentration and the generation number of hyperbranched polyester.     

Synthesis and properties of cationic photopolymerizable hyperbranched polyesters with terminal oxetane groups by the couple-monomer polymerization of carboxylic anhydride with hydroxyl oxetane

The hyperbranched polyesters with terminal oxetane groups were synthesized via couple-monomer methodology based on carboxylic anhydride and hydroxyl oxetane. Two competitive reactions, ring-opening reaction of carboxylic group with oxetane group and esterification of carboxylic group with hydroxyl group, occurred synchronously during the polymerization. The results showed that the hyperbranched polyesters, poly(SA-EHO) and poly(SA-EHPO), were synthesized successfully when succinic anhydride (SA) was selected to react with 3-Ethyl-3-(hydroxymethyl)oxetane (EHO) and 3-ethyl-3-((4-hydroxymethyl)phenoxymethyl)oxetane (EHPO), respectively. The degree of branching was determined to be about 0.7 for poly(SA-EHO) from the ¹H NMR result, which was higher than those reported in literature, indicating that the esterification was dominant. The glass transition temperatures (T_g)s were measured as −11.5 °C for poly(SA-EHO) and 14.3 °C for poly(SA-EHPO) by DSC. The number average molecular weights were 1914 g/mol and 2108 g/mol with the polydispersity indices of 2.39 and 2.28 for poly(SA-EHO) and poly(SA-EHPO), respectively. Both poly(SA-EHO) and poly(SA-EHPO) were added to bisphenol A epoxy resin, EP828, with different contents and cured under UV exposure. From the DMTA and tensile results, the UV cured poly(SA-EHPO) showed higher T_g and tensile strength compared with poly(SA-EHO) because of the existence of phenyl group in poly(SA-EHPO) chain. Moreover, both the T_gs and mechanical strength decreased, whereas the elongation percents at break increased with poly(SA-EHO) and poly(SA-EHPO) increased. This indicates that the flexibility of cured films was improved by the addition of poly(SA-EHO) and poly(SA-EHPO) in the formulations.     

Phosphorus based indole and imidazole functionalized hyperbranched polyester as antimicrobial surface coating materials

Third generation of hyperbranched polyester (HP) synthesized via melt condensation and end-capped with bis indole and imidazole phosphoryl chloride. The modified polyesters subjected to different characterization viz., FTIR, ¹H and ¹³C NMR, GPC and elemental analysis. NMR analysis was used for the determination of OH conversion that demonstrates linear units had a lower reactivity as compared to terminal OH groups in HP. The thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) studies indicated that the HP was stable up to 276 °C and the glass transition temperature was 79.6 °C. After modification of HP, thermal stability was increased for indole modified HP, but the glass transition temperature was decreased. The flame retardance of the hyperbranched polyester was also evaluated with the help of TGA analysis and showed higher value of limiting oxygen index (LOI) for modified polyesters. Morphology of the modified polyester showed more roughness than unmodified HP and this nature positive correlated with bacterial zone of inhibition value. Biological studies showed that the HP and modified HP are able to inhibit the reproduction of gram-positive and gram-negative bacteria. Indole modified HP is showed good activity compared to imidazole modified HP.     

Solution properties of selectively modified hyperbranched polyesters

Simultaneous characterization of the degree of branching and molar mass on a molecular level for hyperbranched polymers is still strongly limited. Therefore model hyperbranched polyesters for development of new chromatographic techniques on the basis of 2,2-bis(hydroxymethyl)propionic acid were synthesized. The two types of OH-functionalities (linear and terminal) of the hyperbranched polymer were selectively modified using different protection groups. The modification of the terminal end groups was carried out using their diol character with the formation of a ketal ring without changing the chemical structure of the linear OH groups. In order to obtain completely non-polar polymer, the linear OH-units were functionalized with an acetyl group. The last modification step was the deprotection of the terminal end groups by removing the ketal ring. Fractions with various molar masses for each modification stage were obtained by preparative fractionation. Extensive characterization by SEC-MALLS, NMR spectroscopy, and viscosity measurements elucidated the dependence of the molecular shape in solution on the polarity. These results were supported by molecular dynamic simulations.     

Amphipathic hyperbranched polymeric thioxanthone photoinitiators (AHPTXs): Synthesis, characterization and photoinitiated polymerization

Amphipathic hyperbranched polymeric thioxanthone (TX) photoinitiators (AHPTXs) were synthesized by introducing TX, and polyethylene glycol monoethylether glycidyl ether (E-PEO), which contained short poly (ethylene oxide) (PEO) chain, into periphery of hyperbranched poly(ethylene imine) (HPEI), as well as low-molecular weight analogue 2-(2-hydroxy-3-(methyl(2,3,4,5,6-pentahydroxyhexyl)amino)propoxy) thioxanthone (MGA-TX). AHPTXs possess UV-vis absorption spectra similar to TX derivatives, and weaker fluorescence emission in comparison to low-molecular weight analogues. AHPTXs can be not only dispersed easily in many solvents and acrylate monomers, but also are soluble in water. AHPTXs are very efficient in photopolymerization of acrylamide (AM), poly(ethylene glycol) diacrylate (PEGDA) and 2,2-bis[4-(acryloxypolyethoxy)phenyl] propane (A-BPE-10). In comparison to low-molecular weight analogues photoinitiator systems 2-(2,3-epoxypropyloxy) thioxanthone/triethylamine (ETX/TEA) and MGA-TX/TEA, AHPTX1 is very efficient for photoinitiation of A-BPE-10 and AM in aqueous solution     

Acetylenes with multiple triple bonds: A group of versatile An-type building blocks for the construction of functional hyperbranched polymers

AB_n-type monomers have been widely used for the synthesis of hyperbranched polymers. These monomers, however, suffer from the problems associated with the tendency of their mutually reactive A and B functional groups toward self-oligomerization. We have explored the possibility of synthesizing hyperbranched polymers using A_n-type monomers, which are stable and easy to prepare and handle, with some being even commercially available. In particular, we have tried to open new synthetic routes to hyperbranched polymers using diynes and triynes as monomers. We have developed metallic [TaBr₅, Cp^∗Ru(PPh₃)₂Cl, etc.] and nonmetallic catalysts (piperidine, DMF, etc.) for polycyclotrimerization, polycycloaddition and polycoupling of the acetylenic monomers. We have synthesized a variety of new hyperbranched polymers including polyarylenes, polytriazoles and polydiynes with high molecular weights and excellent solubility in high yields. The polymers exhibit an array of functional properties such as sensitive photonic response, high light refractivity, large optical nonlinearity, high thermal stability, strong optical limiting power and unusual aggregation-enhanced light emission. Utilizing these unique properties, we succeeded in generating fluorescent images, honeycomb patterns, polymer nanotubes, ferromagnetic ceramics, and nanoparticle catalysts.     

超支化聚酯在环氧树脂改性中的应用

超支化聚合物是一类具有三维树形结构的高度支化的大分子。由于其独特的结构和性能以及可实现工业化生产的潜力,超支化聚合物已经成为高分子材料领域研究的热点之一,并且得到了越来越多的关注。作为一类非常重要的超支化聚合物,超支化聚酯(HBPE)引起了研究人员的极大兴趣。目前,HBPE已经在众多领域获得应用,特别是在环氧树脂改性中的研究发展迅速。综述了HBPE作为改性剂在环氧树脂中的应用研究进展,同时对HBPE在环氧树脂和其他热固性树脂改性中的应用研究方向作了展望。     

Preparation of hyperbranched copolymers of maleimide inimer and styrene by ATRP

Novel hyperbranched copolymers were prepared by the atom transfer radical copolymerization of N-(4-α-bromobutyryloxy phenyl) maleimide (BBPMI) with styrene in 1-methyl-2-pyrrolidone (NMP) using the complex of CuBr/2,2′-bipyridine as catalyst. The copolymerization behavior was investigated by comparison of the conversion of double bond of BBPMI determined by ¹H NMR with that of styrene. The hyperbranched structure of resulting copolymers was verified by gel permeation chromatography (GPC) coupled with multi-angle laser light scattering (MALLS). The influences of dosage of catalyst and monomer ratio on the polymerization rate and structure of the resulting polymers were also investigated. The glass transition temperature of the resulting hyperbranched copolymer increases with increasing mole fraction of BBPMI, f_BBPMI. The resulting copolymers exhibit improved solubility in organic solvents; however, they show lower thermal stabilities than their linear analogues.