UV-curable hyperbranched nanocomposite coatings

Nanoparticles have been used to reinforce polymer matrices since the late 1980s, with promising results. Hyperbranched polymers are densely branched molecules with a globular structure, leading to lower viscosity and many end-groups, creating property-designing opportunities. Here, the two research areas, nanocomposites and hyperbranched polymers, were combined to investigate the possibility of creating a nanocomposite resin, in order to prepare a UV-curable coating system. Nanocomposites were prepared from the hyperbranched polyester Boltorn^® H30, acrylated to 30% and 70%, and the unmodified layered silicate Na⁺montmorillonite, added both before and after the acrylation of Boltorn^® H30. Films prepared from 30% acrylated Boltorn^® H30 with clay added after the acrylation, having a mainly exfoliated structure according to X-ray and TEM, exhibited the largest property improvement, compared with the unfilled film. These property improvements comprised a harder surface, better scratch resistance, better adhesion to metal substrates and a small improvement in flexibility.     

Synthesis and Application of a Hyperbranched Polyester Quaternary Ammonium Surfactant

In the presence of the alkaline catalyst sodium hydroxide, the intermediate of hyperbranched polyester (H20Cl) was prepared by the modification of the hyperbranched polyester Boltorn H20 with epichlorohydrin. Then a new kind of quaternary ammonium functionalized hyperbranched polyester (H20C16 N) was synthesized by the reaction of H20Cl and hexadecyldimethylamine. The characteristics of H20C16 N were determined by FT‐IR, ¹H NMR and TGA. The molecular and molecular weight distribution of H20C16 N were determined by Gel Permeation Chromatography (GPC) and the surface activities of H20C16 N including surface tension (γ) and the critical micelle concentration (CMC) were measured at 25 °C. The H20C16 N reduced the surface tension of water to 30.81 mN/m at concentration levels of 7.94 × 10^?5 mol L^?1 and micellization free energies of the quaternary ammonium salt in its solution showed a good tendency towards adsorption at interfaces. The H20C16 N was applied to the silk fabric. An antimicrobial test of the treated fabrics against Escherichia coli and Staphylococcus aureus was carried out. SEM and XPS analysis were performed to study the dispersion of H20C16 N onto the fabric. All results exhibited excellent antibacterial properties of the hyperbranched polyester quaternary ammonium salt.     

Thermal and mechanical properties of UV-cured acrylated hyperbranched polyester and its blends with linear polyurethane acrylate

Summary  An acrylated hyperbranched polyester was synthesized based on a hyperbranched aliphatic polyester with hydroxyl end-groups by modifying with acryloyl chloride. Approximately 78% of the substitution degree was obtained from¹H NMR and VPO measurements. With the addition of HBP20-A, the T_g and T_s of UV-cured CN972 shifted upward, and the network homogeneity of UV-cured CN972 was reduced. Moreover, thermal stability heated over 310°C, the pendulum hardness, pencil hardness, and tensile strength of UV-cured CN972 were obviously improved by the addition of HBP20-A. However, the thermal degradation temperature of CN972 decreased slightly with the increase of HBP20-A content. State Key Laboratory of Fire Science and Department of Applied Chemistry, Hefei, Anhui, 230026, People’s Republic of China. Institute of Chemical Engineering, Hefei, Anhui 230039, People’s Republic of China. Granted by National Natural Science Foundation of China (No. 50233030 and 20074034)     

Synthesis and characterization of hyperbranched aromatic poly(ester-imide)s

The synthesis and characterization of hyperbranched aromatic poly(ester-imide)s are described. A variety of AB₂ monomers, N-[3- or 4-bis(4-acetoxyphenyl)toluoyl]-4-carboxyl-phthalimide and N-{3- or 4-[1,1-bis(4-acetooxyphenyl)]ethylphenyl}-4-carboxy phthalimides were prepared starting from condensation of nitrobenzaldehydes or nitroacetophenones with phenol and used for synthesis of hyperbranched poly(ester-imide)s containing terminal acetyl groups by transesterification reaction. These hyperbranched poly(ester-imide)s were produced with weight-average molecular weight of up to 6.87 g/mol. Analysis of ¹H NMR and ¹³C NMR spectroscopy revealed the structure of the four hyperbranched poly(ester-imide)s. These hyperbranched poly(ester-imide)s exhibited excellent solubility in a variety of solvents such as N,N-dimethylacetamide, dimethyl sulfoxide, and tetrahydrofuran and showed glass-transition temperatures between 217 and 255 °C. The thermogravimetric analytic measurement revealed the decomposition temperature at 10% weight-loss temperature (T_d¹⁰) ranging from 365 to 416 °C in nitrogen.     

A novel hyperbranched polyester functionalized with azo chromophore: synthesis and photoresponsive properties

Summary A hyperbranched polymer containing azo chromophores on the periphery has been synthesized from transesterification reaction between a hyperbranched polyester bearing peripheral hydroxyl groups and ethyl 4-{4'-[N, Ndi(hydroxyethyl)aminobutoxy]phenylazo}benzoate. The hyperbranched polyester was obtained by adding the AB₂ monomers step by step to a multifunctional core molecule. Narrow molecular weight distribution, with a polydispersity index as low as 1.1, was achieved by this method. The azobenzene- functionalized hyperbranched polymer as well as the corresponding azo monomer showed typical photoresponsive behavior of an azobenzene type molecule. The trans azobenzene units of the hyperbranched polymer could be reversibly switched by UV irradiation to the cis form that recovered slowly to the trans form in the dark. However, significantly less conversion from the trans isomer to the cis isomer was observed for the azobenzenefunctionalized hyperbranched polymer at the photostationary states under the irradiation of UV light, which could be attributed to the increased steric hindrance in the hyperbranched polymer. Received: 1 April 2002 /Revised version: 10 July 2002/ Accepted: 15 July 2002     

Development of optically transparent ZnS/poly(vinylpyrrolidone) nanocomposite films with high refractive indices and high Abbe numbers

A series of optically transparent ZnS‐poly(vinylpyrrolidone) (PVP) nanocomposite films with high refractive indices and high Abbe numbers have been prepared. Mercaptoethanol (ME) capped ZnS nanoparticles (NPs) were introduced into the PVP polymer matrix via simple blending with high nanophase contents. ME‐ZnS NPs of around 3 nm were prepared from zinc acetate and thiourea precursors in N,N‐dimethylformamide using ME as a capping agent. Transparent nanocomposite films with high refractive indices and high Abbe numbers can be easily prepared by a conventional film casting method. TGA results indicated that the ZnS/PVP nanocomposite films exhibit good thermal stability and the measured contents of ZnS NPs in the films agree well with the theoretical values. The refractive indices and the Abbe numbers of the ZnS/PVP nanocomposite films range from 1.5061 to 1.7523 and 55.6 to 20.4 with the content of ME‐ZnS NPs varied between 0 and 80 wt %, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

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 and electronic spectra of some azo disperse dyes derived from N-2,2,2-trifluoroethyl-1,2,3,4-tetrahydroquinoline

Several monoazo dyes suitable for transfer printing have been prepared from N-2,2,2-trifluoroethyl-1,2,3,4-tetrahydroquinoline and compared with their N-ethyl counterparts. The presence of a trifluoroethyl group brings about considerable improvements in lightfastness properties on both polyester and nylon. Electron withdrawal by the trifluoroethyl substituent leads to hypsochromic shifts of the visible absorption band and also results in a marked positive halochromism.     

Photopolymerizaton of hyperbranched aliphatic acrylated poly(amide ester). II. Photopolymerization kinetics

A hyperbranched aliphatic poly(amide ester) ending with hydroxyl groups based on 4‐N,N‐di(2‐hydroxy ethyl)‐4‐ketobutyric acid (DKBA) and 2‐ethyl‐2‐(hydroxymethyl)‐1,3‐propanediol (TMP) was modified with acryloyl chloride, resulting in a radiation‐curable, hyperbranched acrylated poly(amide ester). This hyperbranched polymer was characterized with respect to ultraviolet cure rate, unsaturation conversion, and mechanical properties. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1637–1641, 2001     

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.     

Five and six-coordinate silicon complexes with an O,N,O′-chelating ligand derived from o-hydroxyacetophenone–N-(2-hydroxyethyl)imine

The reaction of o-hydroxyacetophenone–N-(2-hydroxyethyl)imine, 1, with suitable chlorosilanes in the presence of triethylamine gives access to five and six-coordinate silicon complexes. The molecular structures of TBPY-5–34-[2-oxy-κO-acetophenone–N-(2-oxy-κO-ethyl)iminato-κN]diphenylsilane, C₂₂H₂₁NO₂Si, 2, and OC-6–22′-bis[2-oxy-κO-acetophenone–N-(2-oxy-κO-ethyl)iminato-κN]silicon · chloroform, C₂₀H₂₂N₂O₄Si · CHCl₃, 3, have been determined as representative examples.     

含氟超支化聚酯的合成及其性能研究

利用十三氟辛酸对超支化聚酯进行端基改性,得到了含氟超支化聚酯。采用傅里叶变换红外光谱仪、差示扫描量热分析仪等对聚合物进行了表征和分析。结果表明:十三氟酸成功接枝到超支化聚酯上,含氟超支化聚酯的玻璃化转变温度为-20.5℃,含氟超支化聚酯溶液在固含量高达70%时仍具有较低的黏度,该聚合物成膜性好,涂膜的附着力为1级,柔韧性为1 mm,铅笔硬度2 H,抗冲击强度4.9 J/cm2,与水的接触角为105°,具有良好的表面疏水性。     

Aminolysis of 4-(alkoxythiocarbonylthio)benzenesulphonates and derivatives supported on anion exchangers

Several studies attempting the alkoxythiocarbonylation of amines have been performed using alkoxythiocarbonyl reagents supported on the anion exchangers Lewatit MP-5080 and Amberlyst A-26. When polymer-supported O-ethyl dithiocarbonate was reacted with butylamine a mixture of O-ethyl and S-ethyl butylthiocarbamate and N,N′-dibutylthiourea was obtained. The best results in preparing several O-alkyl thiocarbamates were obtained by supporting 4-(alkoxythiocarbonylthio)-3,5-dinitrobenzenesulfonates on Amberlyst A-26 and reacting them with aliphatic amines and aniline. Yields better than 68% were achieved.     

Hyperbranched polyurethane (HBPU)-urea and HBPU-imide coatings: Effect of chain extender and NCO/OH ratio on their properties

Effect of chain extender and NCO/OH ratio on the properties of hyperbranched polyurethane (HBPU)-urea and HBPU-imide coatings were examined. The NCO terminated pre-polymers were prepared by reacting the first (G1) and the second (G2) generation hyperbranched polyester polyols (HBP-G1 and HBP-G2) with excess diisocyanate. The excess NCO content of the prepolymer was reacted with different chain extenders viz., 3-aminopropyl triethoxysilane (APTES), pyromellitic dianhydride (PMDA) and N-hydroxyphthalimide (NHTM) to obtain HBPU-urea or HBPU-imide coatings. The structure–property relationships of the different coatings were investigated by FTIR peak deconvolution, and these data suggests the highest extent of hydrogen bonding interaction for PMDA-based coatings, which increases with increasing NCO/OH ratio. Film properties were evaluated by TGA, DMTA, UTM and contact angle measurements; these results were supported by FTIR deconvolution results. As per contact angle measurements, hydrophobicity of coatings increased by increasing NCO/OH ratio. The adhesive strength, abrasion resistance, alkali resistance, and gel content of the coatings were also evaluated.     

有机硅烷偶联剂改性紫外光固化超支化聚醚基水性聚氨酯的性能

采用超支化聚酯Boltorn H 20与丁二酸酐反应,制备了亲水性超支化聚酯,然后与甲基丙烯酸酯基改性的聚醚基聚氨酯预聚体和3-异氰酸酯基丙基三乙氧基硅烷(IPTS)反应,合成了有机硅烷偶联剂改性紫外光固化聚醚基超支化水性聚氨酯(WHPU)。考察了有机硅烷偶联剂用量对WHPU的耐酸性、固化时间、凝胶质量分数、附着力、水接触角、水吸附率、乳液粒径分布及热稳定性的影响。结果表明,当IPTS与Boltorn H 20中羟基的摩尔比为6/16时,固化后的WHPU膜的凝胶质量分数为92%,在玻璃表面的附着力达到0级;与不含有机硅烷偶联剂的WHPU相比,该涂膜的水接触角和热稳定性分别提高了34°和22℃,其吸水率从13.8%降低到4.3%。     

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.     

新型超支化聚酯对PVC力学及流变性能影响的研究

研究了BOLTORNTM型超支化聚酯对硬质聚氯乙烯(PVC)力学及流变性能的影响,并初步与传统加工助剂ACR进行了比较。结果表明,在100份的PVC中加入10份的超支化聚酯BOLTORNTMH40,材料的拉伸强度和断裂伸长率分别达到最大值39.58MPa和30.25%,拉伸强度比加入相同量的BOLTORNTMH20、H30要分别高4.2%、27.93%,而断裂伸长率则分别高400.1%、97.1%;在100份PVC中加入8份的超支化聚酯BOLTORNTMH20,材料的冲击强度达到最大值20.53kJ/m2;BOLTORNTM超支化聚酯与传统的加工助剂ACR相比,超支化聚酯对PVC有着更好的流变与塑化效果;另外,超支化聚酯可以降低PVC的黏度,随着超支化聚酯用量的增加,PVC黏度降低幅度增加。     

超支化水性聚氨酯乳液的制备及性能研究

以顺丁烯二酸酐改性的超支化聚酯Boltorn H20、聚四氢呋喃2000和异佛尔酮二异氰酸酯为主要原料合成了超支化水性聚氨酯乳液,研究了改性超支化聚酯Boltorn H20的合成,以及改性超支化聚酯中羧基含量、初聚—NCO/—OH物质的量比、催化剂用量等对制备水性聚氨酯的影响,并探讨了亲水基团含量、乳化温度、中和度等因素对乳液及涂膜性能的影响,进一步使用傅里叶红外和热重分析分别对超支化聚氨酯涂膜的结构和热稳定性能进行了表征及测试。结果表明,在不加催化剂,初聚—NCO/—OH物质的量比为2∶1,亲水基团含量为2.05%的条件下,合成得到的含固量为30%的超支化水性聚氨酯乳液稳定性好。由此得到的超支化聚氨酯薄膜的耐水性和热稳定性较好。     

Synthesis of Fluorinated Hyperbranched Polymers and Their Use as Additives in Cationic Photopolymerization

Summary: A fluorine containing hyperbranched polymer was synthesized by modifying an aromatic‐aliphatic hyperbranched polyester with a semifluorinated alcohol via a Mitsunobu reaction and was subsequently used as an additive in cationic photopolymerization of an epoxy resin. The remaining OH groups of the fluorinated hyperbranched polymer interact with the polymeric carbocation through a chain‐transfer mechanism inducing an increase in the final epoxy conversion. The fluorinated HBP induces modification of bulk and surface properties, with an increase in T_g and surface hydrophobicity already reached at very low concentration. The HBFP additive can, therefore, protect the coatings from aggressive solvents, increases hardness, and allows the preparation of a low energy surface coating.

Synthesis of fluorinated hyperbranched polyester.     

Fluorinated hyperbranched polyester acrylate used as an additive for UV curing coatings

The fluorinated hyperbranched polyester acrylate (FHPA) was synthesized by modifying the hyperbranched polyester Boltorn H20 with fluorinated isocyanate, and characterized with ¹H NMR and FTIR spectroscopic analysis. The water and oil wettability of the UV cured film with FHPA as an additive was investigated by measuring the contact angle. The results showed that an extremely low concentration of FHPA, even below 0.1 wt%, resulted in efficient decrement of the surface tension of UV cured film to 10–15 mN/m, and thus makes the film highly hydrophobic and oleophobic. The film with FHPA addition was stable in acidic and neutral solutions, and still had good water repellency after immersion in a pH 1 solution for several days. The X-ray photoelectron spectroscopic analysis confirmed that the film surface was enriched with fluorinated species. Moreover, the molecule with the highest average number of perfluoroalkyl groups had the highest tendency to aggregate at the surface of the UV cured film.