Syntheses and properties of hyperbranched polybenzoxazole by thermal cyclodehydration of hyperbranched poly[o‐(t‐butoxycarbonyl)amide] via A2 + B3 approach

The syntheses and properties of hyperbranched poly(o‐hydroxyamide) [poly(HAB‐BCC)‐ABP], poly[o‐(t‐butoxycarbonyl)amide] [poly(HAB‐BCC)‐ABP‐t‐BOC], and polybenzoxazole [poly(HAB‐cycloBCC)] were examined. Poly(HAB‐BCC)‐ABP was obtained from the polycondensation reaction of 3,3‐dihydroxy‐4,4′‐diaminobiphenyl (HAB) as an A₂‐monomer and 1,3,5‐benzenetricarboxylchloride (BCC) as a B₃‐monomer with 2‐amino‐4‐t‐butylphenol (ABP) in NMP in the presence of pyridine for 24 h. The reaction of poly(HAB‐BCC)‐ABP and di‐t‐buthylcarbonate (DiBOC) was performed to obtain the corresponding poly(HAB‐BCC)‐ABP‐t‐BOC with pendant t‐BOC groups. The thermal cyclodehydration of poly(HAB‐BCC)‐ABP‐t‐BOC was carried out in the film sate at 400 °C, affording the poly(HAB‐cyclo‐BCC) in quantitative yield. Furthermore, the solubilities and thermal properties of these polymers were examined. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3640–3649, 2006     

Synthesis and characterization of highly stable blue‐light‐emitting hyperbranched conjugated polymers

Polyfluorene homopolymer ( P1 ) and its carbazole derivatives ( P2 – P4 ) have been prepared with good yield by Suzuki coupling polymerization. P2 is an alternating copolymer based on fluorene and carbazole; P3 is a hyperbranched polymer with carbazole derivative as the core and polyfluorene as the long arms; P4 is a hyperbranched polymer with carbazole derivative as the core and the alternating fluorene and carbazole as the long arms. These polymers show highly thermal stability, and their structures and physical properties are studied using gel permeation chromatography, ¹H NMR, ¹³C NMR, elemental analysis, Fourier transform infrared spectroscopy, thermogravimetry, UV–vis absorption, photoluminescence, and cyclic voltammetry (CV). The influence of the incorporation of carbazole and the hyperbranched structures on the thermal, electrochemical, and electroluminescent properties has been investigated. Both carbazole addition and the hyperbranched structure increase the thermal and photoluminescent stability. The CV shows an increase of the HOMO energy levels for the derivatives, compared with polyfluorene homopolymer ( P1 ). The EL devices fabricated by these polymers exhibit pure blue‐light‐emitting with negligible low‐energy emission bands, indicating that the hyperbranched structure has a strong effect on the PLED characteristics. The results imply that incorporating carbazole into polyfluorene to form a hyperbranched structure is an efficient way to obtain highly stable blue‐light‐emitting conjugated polymers, and it is possible to adjust the property of light‐emitting polymers by the amount of carbazole derivative incorporated into the polymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 790–802, 2008     

Synthesis of photocrosslinkable hyperbranched polyesters and their film properties

Hyperbranched polyesters with terminal methacryloyl groups (HBPEAc) were synthesized by the one‐pot polyaddition of bisphenol A diglycidyl ether and trimesic acid in the presence of methacrylic acid with a number‐average molecular weights of 5100–7700 in 70–83% yields. The photoradical polymerization of HBPEAc was examined in the presence of 2‐methyl‐1‐[4‐(methylthio)phenyl]‐2‐morpholinopropan‐2‐one (Irgacure 907®) as a photoinitiator in the film state upon UV irradiation to afford the corresponding cured films quantitatively. The crosslinking densities of the cured films of HBPEAc were higher than those of the corresponding linear ones, and birefringence cannot be detected for the cured films of HBPEAc because of their random structures. Furthermore, an alkaline‐developable hyperbranched polyester containing pendant carboxyl groups (HBPEAc‐COOH) was prepared by the addition reaction of HBPEAc with cis‐1,2,3,6‐tetrahydrophthalic anhydride, and its patterning properties were examined to give the resolution of a 55‐μm‐line and 275‐μm‐space pattern by UV irradiation with 700 mJ/cm². © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4642–4653, 2005     

Synthesis of a novel one‐pot approach of hyperbranched polyurethanes and their properties

A new method for the synthesis of hyperbranched polymers involving the use of AB_x macromonomers containing linear units have been investigated. Two types of novel hyperbranched polyurethanes have been synthesized by a one‐pot approach. The structures of monomers and polymers were characterized by elemental analysis, ¹H NMR, ¹³C NMR, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The hyperbranched polymers have been proven to be extremely soluble in a wide range of solvents. Polymer electrolytes were prepared with hyperbranched polymer, linear polymer as the host, and lithium perchlorate (LiClO₄) as the ion source. Analysis of the isotherm conductivity dependence of the ion concentration indicated that these hyperbranched polymers could function as a “solvent” for the lithium salt. The conductivity increased with the increasing concentration of hyperbranched polymers in the host polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 344–350, 2002     

Chemical modification of hyperbranched ultrathin films on gold and polyethylene

Synthetic methods for modifying the carboxylic acid groups of hyperbranched thin film grafts were studied. Amidation, esterification, reduction, and alkylation reactions of carboxylic acid derivatives that proceed in high conversion (>90%) are described. The stability of ultrathin, hyperbranched film grafts attached to self‐assembled monolayers on gold to conditions of strong base, strong acid, heat, and organic solvents is detailed. Practical procedures that can be used to prepare and modify poly(acrylic acid) hyperbranched grafts on gold, polyethylene film, and powder for use in the synthesis of cationic polyelectrolyte grafts, for use in the synthesis of poly(allyl alcohol) grafts, for use in the synthesis of poly(allyl ester) grafts, and for use as substrates for organometallic chemistry and further graft chemistry are discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3944–3953, 2000     

Synthesis of hyperbranched polymers with precise conjugation length

A set of AB₂ type monodisperse conjugated oligomers carrying two bromo functional groups and one boronic ester functional group were prepared by iterative deprotection and Sonogashira cross‐coupling reactions. Suzuki polycondensation of these AB₂ type monodisperse oligomers afforded hyperbranched polymers. The hyperbranched conjugated polymers we prepared possess not only precisely controlled conjugation length like monodisperse conjugated oligomers but also the structural feature of hyperbranched polymers. Optical property investigation demonstrated that the maximum absorption and emission wavelength red‐shifted along with the increasing of the conjugation length between the two branching points and the hyperbranched structure could effectively reduce the aggregation of the conjugated polymer chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1084–1092, 2007     

Synthesis and magnetic properties of complexes of a conjugated hyperbranched polymer containing bithiazole rings

A novel conjugated hyperbranched polymer containing bithiazole rings（PBTADB） was synthesized by polycondensation of 1,3,5-benzenetricarboxaldehyde and 2,2’-diamino-4,4’-bithiazole（DABT）.The structure of the hyperbranched polymer was confirmed by FT-IR and ¹H-NMR.PBTADB dissolved in organic polar solvents such as DMSO and NMP.Bithiazole rings were introduced to provide bidentate N-donor sites for binding metal ions.The metal complexes were prepared by chelation of the polymer with Co²⁺ and Sm³⁺.The magnetic behavior of coordination compounds was measured as a function of magnetic field strength（0-4.8×10⁶ A/m） at 5 K and as a function of temperature（5-300 K） at magnetic field strength of 2.4×10⁶ A/m.The magnetic hysteresis loops of PBTADB-Sm³⁺and PBTADB-Co²⁺showed the typical ’S’ shape at 5 K with the Curie-Weiss temperature T_θ=96 K and 41 K respectively.The results show that they exhibit properties of soft ferromagnetic materials.     

超支化聚芴的合成与性能研究

采用2,7-二(4-羟基苯基)-9,9-二烷基芴(A2)与四对甲基苯磺酸季戊四醇酯(B4)通过A2+B4型缩聚反应合成了一系列共轭型超支化聚合物.利用紫外和荧光谱对聚合物予以表征,结果表明,此类聚合物均可发出稳定、纯正的蓝光.DSC和TGA显示,4种聚合物在150℃以下没有明显的相态变化,300℃以内无明显的热分解现象,这表明此类聚合物具有良好的热稳定性,有利于材料的发光效率及发光稳定性.     

Synthesis of polycarbosilanes by A2 + Bn (n = 2, 3, and 4) type hydrosilylation reaction and evaluation of their refractive index properties

Polycarbosilanes were synthesized by hydrosilylation reaction of A₂ monomer containing bis Si? H moieties and B_n (n = 2, 3, and 4) monomers containing di‐, tri‐, and tetra‐vinyl groups in the presence of Karstedt's catalyst. The corresponding linear polycarbosilanes (LPC) and hyperbranched polycarbosilanes (HBPC) having M_n 2200–51,500 were obtained in 34–94% yield, without any gel product. The values of refractive index (n_D) of the synthesized LPC and HBPC were in the range from 1.460 to 1.711, and were consistent with the structures of the synthesized products. In the case of HBPC, the values of n_D increased with increase of number‐average molecular weight (M_n), molecular weight distribution (M_w/M_n), and glass transition temperature (T_g), apparently because of increased density due to the presence of microgels, that is, high refractive index hyperbranched carbosilanes could be synthesized by A₂ + B_n (n = 3 and 4) method. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

超支化分子桥联受阻酚抗氧化剂的合成与表征

以正十八胺为核的1.0代超支化大分子和β-(3,5-二叔丁基-4-羟基苯基)丙酰氯为原料,通过酰胺化缩合反应,合成了一种具有长链烷基和2个受阻酚基团的新型超支化分子桥联受阻酚类抗氧化剂.通过正交实验确定了超支化分子桥联受阻酚类抗氧化剂的最佳合成体系为:3,5-丙酰氯为酰化剂、K_2CO_3为缚酸剂、苯和水为反应溶剂.通过条件优化实验确定了超支化分子桥联受阻酚类抗氧化剂的最佳合成条件为:3,5-丙酰氯与1.0代超支化大分子的物质的量比为6∶1、反应温度为25 ℃、反应时间为12 h、体系苯与水体积比为6∶1、3,5-丙酰氯与缚酸剂K_2CO_3的物质的量比为1∶1,在此条件下,超支化分子桥联受阻酚类抗氧化剂的收率高达75.5%.FT-IR和1H NMR证实了合成抗氧化剂的化学结构与其理论结构相符.超支化分子桥联受阻酚类抗氧化剂在聚乙烯树脂中的抗氧化性能优于抗氧化剂1076,且随着烷基链长度的增加,抗氧化性能增强.     

Structures and electrical properties of ferroelectric copolymer ultrathin films

Ultrathin films of ferroelectric copolymer vinylidenefluoride and trifluoroethylene, P(VDF-TrFE), were successfully obtained by spin-coating and their nanoscale structures and electrical properties were studied utilizing atomic force microscopy (AFM). We succeeded in obtaining ultrathin copolymer films on graphite whose thickness ranged from 1 nm to several tens of nanometers by controlling concentration of copolymer solutions in methylethylketone. We found that ultrathin films thinner than 4 nm showed layered structures whose layer thickness was about 0.5 nm. On the other hand, films thicker than 4 nm formed typical edge-on lamellar crystal structures. Furthermore, we investigated surface potential distribution and piezoelectric property by AFM-based techniques and discussed interaction between electrical dipoles in the molecular chains and graphite substrate.     

Synthesis and characterization of a novel nonlinear optical hyperbranched polymer containing a highly performing chromophore

We report herein the peripheral functionalization of a high glass transition temperature hyperbranched polyimide with a new and highly performing electro‐optic chromophore for the elaboration of a second‐order nonlinear optical material. In this study, the CPO1 chromophore was selected for its very high quadratic hyperpolarizability coefficient (μβ = 31,000 ? 10^?48 esu at 1990 nm) and its ease of synthesis in multigram scale. As a result, the new electro‐optic polymer was characterized by an r₃₃ coefficient around 40 pm/V at 1.5 µm, although the poling conditions were not optimized. For sake of comparison, the electro‐optic r₃₃ coefficient of our previously reported similar polymer functionalized with the well‐known Disperse Red One chromophore was also measured using the technique and gave a much lower r₃₃ coefficient. This study underscores that hyperbranched polymers are particularly promising matrices to host highly efficient chromophore to achieve more efficient and more stable electro‐optic devices than classical linear polymers. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and nonlinear optical properties of fluorine-containing naphthalocyanines

The fluorine-containing metal naphthalocyanines [F16NcGaCl] (7) and [(F16NcGa)2O] (8), which represent the first examples of peripherally fluorine substituted naphthalocyanines, were synthesized, and the nonlinear optical transmission was studied. Peripheral substitution by fluorine atoms enhances the solubility and photostability of the naphthalocyanines. In particular, for the axially mu-oxo-bridged naphthalocyanine dimer 8, practically no aggregation was observed in organic solvents and it has proved to be an efficient optical limiter when irradiated with laser light pulses at the wavelength of 532 nm, with pulse duration of 5 ns and repetition rate of 20 Hz.     

Influence of solution conditions on formation of amphiphilic hyperbranched polyanion/linear polycation multilayer films

Amphiphilic hyperbranched polyester (P2) consisting of a hydrophobic core, surrounded by aromatic carboxylic acids, is self-assembled into aggregates in aqueous solution at pH region of 3.8–4.7 and in THF–water mixed solution at THF/water volume ratio of 1/100–1/10. With P2 in both aqueous and THF–water mixed solution as polyanion and linear poly(diallydimethylammonium chloride) (PDAC) as polycation, self-assembled films were successfully formed by layer-by-layer dipping. The solution condition of P2, including the pH of aqueous solution and the THF/water volume ratio, affected not only the absorption behavior of P2 but also the surface morphology and hydrophilicity of the films with P2 as the outmost layer. At lower pH or higher THF/water volume ratio the aggregation of P2 in solution was enhanced, thus resulting in higher adsorption rate for P2, more rough and less hydrophilic surface for the films.     

Synthesis and optoelectronic properties of alternating benzofuran/terfluorene copolymer with stable blue emission

The solution processable alternating benzofuran/terfluorene copolymer bearing side oxadiazole groups ( PBF‐OXD ) was synthesized and its optoelectronic properties and color stability were investigated. Electron‐deficient and stereohindered oxadiazole units were used as pendent groups to compensate for the poor electron‐transporting ability of a p‐type polymer backbone, to depress the intermolecular π‐stacking, and to improve solubility while retaining polymer blue emission. PBF‐OXD showed a glass transition at 135 °C and an onset decomposition temperature of ～345 °C. A simple EL device, with the configuration of ITO/PEDOT:PSS/ PBF‐OXD /Ba/Al, displayed a stable blue emission (λ_max = 434 nm), good color purity (full width half‐maximum = 59 nm), maximum brightness of 1400 cd/m², and a maximum luminance efficiency of 0.95 cd/A. The PL and EL spectra changed slightly on annealing and on increasing the applied voltage. These results show that the as‐synthesized copolymer PBF‐OXD had integrated respective functions of its different building blocks and exhibited good thermal and color stability with improved EL performance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5488–5497, 2009     

Synthesis of water-soluble hyperbranched polymer and its application in acrylic latex

A water-soluble hyperbranched polymer (WHBP), obtained from a second generation of hyperbranched polyester and maleic anhydride, was studied. Its effects on the properties of acrylic latexes, which were based on emulsion polymerization of butyl acrylate (BA), methyl methacrylate (MMA), acrylic acid (AA) and WHBP, and latex film were discussed. The characteristics of WHBP were determined by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared (FTIR) and gel permeation chromatography (GPC). Particle size and morphology of latex particles were confirmed by dynamic light scattering (DLS) and transmission electron microscope (TEM). The investigation showed that WHBP could be used in emulsion polymerization, and that latex of poly(BA-MMA-WHBP) was more stable than that of poly(BA-MMA-AA). The hardness of latex film increased from 2B to HB when WHBP was used.     

Anti-biofouling properties of amphiphilic phosphorylcholine polymer films

Surfaces of amphiphilic phosphorylcholine polymer (PC1036) prepared by spin-coating were characterized by spectroscopic ellipsometry, water contact angle and atomic force microscopy. The antifouling properties of the PC1036 films to marine benthic diatom Nitzschia closterium MMDL533 were also investigated. The results showed that the dry PC1036 film promoted the adhesion of N. closterium MMDL533 because the hydrophobic lauryl groups were present in the film surface. The 2 h-swelled PC1036 films had excellent anti-fouling properties with extremely low attachment densities and retention densities no matter what the annealing temperature was. The thickness of the coated films lower than 147 Å had a profound effect on the film anti-fouling properties. Otherwise, when the film thickness was higher than that value, there was no more improvement of diatom cell reduction observed. The annealing temperature had only a little effect on the film resistant to diatom adhesion, which might be attributed to two factors including the PC group packing densities in the outer PC layer and the equilibrated water volume fraction in the 2 h-swelled PC1036 films.     

Properties and morphologies of UV‐cured epoxy acrylate blend films containing hyperbranched polyurethane acrylate/hyperbranched polyester

The properties and morphologies of UV‐cured epoxy acrylate (EB600) blend films containing hyperbranched polyurethane acrylate (HUA)/hyperbranched polyester (HPE) were investigated. A small amount of HUA added to EB600 improved both the tensile strength and elongation at break without damaging its storage modulus (E′). The highest tensile strength of 31.9 MPa and an elongation at break around two times that of cured pure EB600 were obtained for the EB600‐based film blended with 10% HUA. Its log E′ (MPa) value was measured to be 9.48, that is, about 98% of that of the cured EB600 film. The impact strength and critical stress intensity factor (K_1c) of the blends were investigated. A 10 wt % HUA content led to a K_1c value 1.75 times that of the neat EB600 resin, and the impact strength of the EB600/HPE blends increased from 0.84 to 0.95 kJ m^?1 with only 5 wt % HPE addition. The toughening effects of HUA and HPE on EB600 were demonstrated by scanning electron microscopy photographs of the fracture surfaces of films. Moreover, for the toughening mechanism of HPE to EB600, it was suggested that the HPE particles, as a second phase in the cured EB600 film, were deformed in a cold drawing, which was caused by the difference between the elastic moduli of HPE and EB600. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3159–3170, 2005