Synthesis and characterization of alkali‐soluble photosensitive polysiloxane urethane acrylate

A new negative temperature coefficient of resistor (NTCR) thermistors based on nitrile butadiene rubber/magnetite (NBR/Fe₃O₄) nanocomposites were successfully fabricated by conventional roll milling technique. X‐ray diffraction and transmission (TEM) analysis showed that the product is mainly magnetite nanoparticles with diameter of 10‐13 nm. The microstructure of (NBR/Fe₃O₄) nanocomposites were examined by scanning electron microscopy (SEM) and FTIR spectroscopy. The dispersion of magnetite nanoparticles in the NBR rubber matrix and interfacial bonding between them were rather good. The thermal stability of nanocomposites was also obviously improved with the inclusion of the magnetite nanoparticles. The thermal conductivity, thermal diffusivity and specific heat of nanocomposites were investigated. The electrical conductivity of the NBR/Fe₃O₄ increases with the rise in temperature exhibiting a typical negative temperature coefficient of resistance (NTCR) behavior like a semiconductor. The nature of the temperature variation of electrical conductivity and values of activation and hopping energy, suggest that the transport conduction process is controlled by hopping mechanism. Values of characteristics parameters of the thermistors like thermistor constant, thermistor sensitivity and thermistor stability is quite good for practical application as NTCR devices at high temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and properties of hyperbranched polyurethane acrylate used for UV curing coatings

The hyperbranched polyurethane acrylate (HPUA) was synthesized through the addition of hyperbranched polyurethane endcapped by hydroxyl groups (HPU-OH), with the semiadduct urethane monoacrylate (IPDI-HEA). The HPU-OH was prepared by the amidation reaction of diethanolamine with isophorone diisocyanate. The molecular structure of HPUA was characterized by FTIR and ¹H NMR analyses. The number average molecular weight and its polydispersity index were measured by GPC to be 7714 g mol⁻¹ and 1.24, respectively. The HPUA was blended with epoxy acrylate EB600 and difunctional monomer TPGDA in different ratios, and exposed to a UV lamp for photopolymerization in the presence of Runtecure 1104 as a photoinitiator at room temperature. The photopolymerization rate and final unsaturation conversion reached to the highest values with only 5 wt% HPUA addition, whereas decreased as further added. The tensile strength of UV-cured films was improved by adding less than 10 wt% HPUA without damaging the modulus, having the value of 62.56 MPa for EB₉₀HPUA₁₀ film. Besides, the elongation at break increased continuously with the addition of HPUA, reaching to 130% for EB₇₀HPUA₃₀ film. Moreover, the impact strength was greatly enhanced by the addition of HPUA, possessing nearly two times high for EB₇₀HPUA₃₀ film compared with pure EB600 film. However, the T_g decreased as HPUA was added from the DMTA measurements. According to the ratios of T_s/T_g the HPUA has good compatibility with EB600/TPGDA resin.     

Self-initiated photopolymerization of hyperbranched acrylates

Self-initiated photopolymerization of hyperbranched acrylates (HBAs) has been investigated. The photopolymerization progress was monitored by differential photo-calorimetry (DPC). It was shown that HBAs were able to self-initiate photopolymerization rapidly under the irradiation of medium-pressure mercury lamp. This behavior was explained by the longer wavelength absorption (286 nm) of HBAs, which results from the overlapping of π-conjugated orbitals of acrylate groups. Autoacceleration effect was observed. The autocatalytic model was used to analyze the photopolymerization kinetics and found to well match the experimental data. It was found that acceleration stage ended at low conversion (α_Rm < 0.11), and the final conversion α_f was lower than 40% in most cases. This was attributed to the poorer ability of HBAs to generate primary radicals and thus the insufficiency of free radicals in polymerization. Factors in favor of generating primary radicals extended the autoacceleration stage to higher conversion and gave higher final conversion. The values of activation energy were calculated to be in the range of 5.7–7.5 kJ mol⁻¹, analogous to those for the free radical photopolymerization of acrylate monomers in the presence of photoinitiator.     

光敏有机硅聚氨酯丙烯酸酯预聚体性能的研究

考查了光引发剂、活性单体对光敏有机硅聚氨酯丙烯酸酯预聚体（PSUA）胶膜的耐水性、拉伸强度、伸长率、硬度、柔韧性和热稳定性的影响。结果表明,胶膜具有优良的耐水性,吸水性低于4％。含单官能度单体的PSUA胶膜的接触角大于含多官能度单体的,含有IBOA的体系接触角达103．6°;当选择引发效率高的裂解型光引发剂,用量为0.5％～1％时,胶膜具有较高的接触角。含多官能度单体胶膜的拉伸强度高于含单官能度单体的体系,但伸长率较小。含TMPTA体系的胶膜的硬度最大,为0．575。胶膜具有较好的柔韧性和热稳定性,其柔韧性达到1mm级,在300℃时失重为4.61％。     

Synthesis and properties of carbazole-based hyperbranched conjugated polymers

Carbazole-based novel hyperbranched conjugated polymers linked with triphenylamine and benzene moieties were synthesized by Sonogashira coupling polycondensation of N-octadecyl- and N-octyl-3,6-diethynylcarbazoles with tris(4-iodophenyl)amine and 1,3,5-tribromobenzene. Solvent-soluble polymers with number-average molecular weights in the range of 3500-21,000 were obtained in 48-66% yields. The UV-vis absorption bands of the polymers were red-shifted compared to that of carbazole, indicating the extension of conjugation length. The polymers emitted blue-green fluorescence with high quantum yields up to 67% in CHCl₃. Poly(1/3) containing triphenylamine units emits visible light and shows unique solvatochromism. The polymers were electrochemically redox-active.     

Synthesis and characterization of novel alkyd-silicone hyperbranched nanoresins with high solid contents

Hyperbranched alkyd-silicone nanoresins (ASiHBRs) with high solid content were synthesized by etherification reaction between a hyperbranched alkyd resin (HABR) and Z-6018 silicone. ASiHBRs were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and several other techniques. NMR spectra show the presence of aromatic rings, -Si-O and -C-O; grafting was successful. The molar masses of ASiHBRs determined by GPC are higher than that of HABR. The hydroxyl values decrease with increasing silicone content. ASiHBRs have low viscosities what allows easier film formation. Hydrodynamic dimensions, refractive indices, glass transition temperatures, gloss and hardness of ASiHBRs increase with increasing silicone contents. Low contents of volatile organic compounds provide more environmentally friendly coatings.     

Preparation and properties of novel high performance UV-curable epoxy acrylate/hyperbranched polysiloxane coatings

Novel high performance UV-curable coatings based on epoxy acrylate (EA) oligomer and hyperbranched polysiloxane (HPSi) were prepared, the effect of HPSi on the processing of uncured EA/HPSi system and integrated performance of cured resins is evaluated. Results show that a small addition of HPSi can greatly decrease the viscosity of EA oliogmer, while the viscosity almost does not reduces as the content of HPSi continuously increases owing to the interaction between HPSi and EA oligomer. The integrated performance of cured resins is closely related with the content of HPSi, those resins with suitable contents of HPSi have significantly improved toughness and stiffness as well as thermal and moisture resistance. The origin of all these changes in macro-performance are investigated and proved to be resulted from the variety in the chemical structure and crosslinking density induced by the addition of HPSi. These attractive features of EA/HPSi resins suggest that HPSi is an effective multi-functional diluent for UV-curable EA resin, and the method proposed herein is a new approach to develop high performance UV-curable coatings, solvent-free resins, etc., for cutting-edge industries.     

Study on properties of a novel photosensitive polysiloxane urethane acrylate for solder mask

The photosensitive and physical and mechanical properties of a novel polysiloxane urethane acrylate (PSUA) for solder mask were investigated using real‐time FTIR, DMTA and TGA. It is noted that PSUA showed a notable photosensitivity and a good compatibility with the acrylic monomers and resins. PSUA cured film exhibited excellent thermal property, tensile strength and toughness, and chemical resistance. The decomposition temperature of PSUA was 402 °C. Thermal weight losses of pure PSUA cured film at 300 °C were only 5%. Elongation percentage of PSUA cured film was up to 59%. PSUA resin can be used for solder mask materials for printed circuit. Technology performances of photosensitive imaging flexible solder mask containing PSUA answers operating requirements of the solder masker for printing circuit board. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of carbon nanofillers on anticorrosive and physico-mechanical properties of hyperbranched urethane alkyd coatings

Effects of three geometrically different carbon nanofillers (CNs) namely carbon black, multiwall carbon nanotubes and graphene on the anticorrosive and physico-mechanical properties of hyperbranched alkyd resin (HBA) based coatings were investigated. Hyperbranched urethane alkyd coatings (HBUA) were made by curing the synthesized resin with hexamethylene diisocyanate trimer. All the carbon fillers are treated with a surfactant (Nonidate-P40) to achieve a uniform dispersion. The addition of surfactant treated CNs to HBUA resulted in a significant improvement in the corrosion resistance and mechanical properties in comparison with the neat HBUA coating. Among the HBUA/CN composites, the improvement in corrosion resistance was found to be superior in the case of HBUA/graphene composite. Transmission electron microscope (TEM) clearly indicated the uniform dispersion of carbon nanofillers in the resin. The uniform dispersion of CNs is believed to originate from an interaction of π electron clouds of CNs with the delocalized π electrons of Nonidet-P40 and H-bonding interaction between Nonidet-P40 and the HBA. This type of interaction does not disturb the π electron clouds of MWCNTs as opposed to chemical functionalization strategy.     

Synthesis and characterization of glycerol-adipic acid hyperbranched polyesters

The structure and molecular weight of the hyperbranched polyesterification of adipic acid and glycerol were characterized by ¹³C NMR spectroscopy and size-exclusion chromatography as a function of reaction time and reaction stoichiometry. The glycerol substitution patterns and the extent of reaction of both glycerol and adipic acid were determined by NMR. The glycerol species concentrations determined by NMR were used with a Macosko–Miller conditional probability model to predict the hyperbranched polyester weight-average molecular weight. The model accommodated the difference in primary and secondary –OH reactivity and any substituent effects to glycerol –OH reactivity. In all cases, the predicted weight-average molecular weights were in excellent agreement with the absolute molecular weights determined by size-exclusion chromatography with light scattering detection.     

超支化半芳香型聚酰胺的合成及其表征

利用溶液聚合方法,以对苯二胺与氨三乙酸为原料,制备了A2+B3型超支化半芳香型聚酰胺。利用傅立叶变换红外光谱(FTIR)、核磁共振谱(1HNMR)对制备的超支化半芳香型聚酰胺进行了结构表征。用乌式粘度计、热重分析(TG)测定了超支化半芳香型聚酰胺的粘度和热稳定性,并从微观反应机理,研究了反应条件对聚合物特性粘度的影响     

Syntheses, characterization, and energy transfer properties of benzothiadiazole-based hyperbranched polyfluorenes

A series of benzothiadiazole-based (BT) hyperbranched polyfluorene copolymers with various branching degrees (5-40%) were designed and synthesized. TGA and film annealing tests showed the substantial thermal stability of these highly branched polymers. The optical performance of the polymers in solutions and as films, and their electrochemical properties were characterized. The energy transfer (ET) processes in these hyperbranched conjugated polymers, both in solutions and in the solid state, were also investigated. With the change of the solution concentration and the branching degree, the energy transfer efficiency of the polymers varied in solutions and the main photoluminescence (PL) peaks changed from blue to green region. As films, only green light emitted from BT units. In addition, the PL efficiency of the films decreased dramatically with the increase of branching degrees. All these features demonstrated that highly branched structure would effectively impede the intra- and interchain energy migration, especially in solutions, and remarkably influence the ET process in the solid state, which resulted in low PL efficiency.     

Synthesis and second-order nonlinear optical properties of hyperbranched polymers containing pendant azobenzene chromophores

Two hyperbranched polymers with methyl ester (P1) and epoxy (P2) terminal groups containing pendant azobenzene chromophores were prepared through an “A₂ + B₃” approach used for second-order nonlinear optical materials. Their chemical structures were characterized by NMR and GPC analyses. The polymers have good solubility in common organic solvents and film-forming ability. The pure films were fabricated successively without doping into other matrices. The poled films exhibit high second-harmonic generation coefficients (>50 pm/V) due to the three-dimensional spatial isolation effect resulting from their highly branched structures. The optical nonlinearity of the poled P2 film is thermally more stable than that of P1 due to the cross-linking of epoxy groups with carboxylic acid groups in the former during poling. The onset decay temperature of SHG intensity of P2 was determined to be at around 155 °C, which was 20 °C higher than that of P1.     

有机硅聚氨酯丙烯酸酯预聚物的合成

以异佛尔酮二异氰酸酯（IPDI）、烷羟基硅油（SD9134）和丙烯酸β-羟乙酯（HEA）为原料,合成了一种UV固化有机硅聚氨酯丙烯酸酯预聚物（PSUA）。探讨了原料、催化剂用量、反应温度等因素对反应的影响。确定最佳反应条件为：以烷羟基硅油SD9134和IPDI为主要原料,DBTDL为催化剂,其加入量为0．05％～0．1％,反应前3步在20～40℃下反应,第4步反应温度不超过70℃,并通过IR和GPC表征了PSUA的结构。     

Synthesis and characterization of novel hyperbranched alkyd and isocyanate trimer based high solid polyurethane coatings

In the present work, hyperbranched urethane alkyd high solid coatings were formulated by mixing hyperbranched alkyd and isocyanate trimer. Initially, a second generation hyperbranched polyol (HBP) was synthesized using dipentaerythritol (DPE) as a core material and 2,2-bis(methylol)propionic acid (BMPA) as a chain extender. This was reacted with varying concentrations of linseed oil fatty acid (LOFA) to make a series of hyperbranched alkyd (HBA) resins. Viscosity and volume solid of the HBA resins were measured. The resins were characterized by Fourier transform infrared (FTIR), and ¹³C Nuclear magnetic resonance (¹³C NMR) spectroscopic techniques. The hyperbranched alkyd resins containing varying amount unreacted hydroxyl groups were cured with hexamethylene diisocyanate (HDI) trimer (Desmodur N 3390) depending on their NCO: OH ratio to make hyperbranched urethane alkyd coatings. A series of such coatings were made by mixing HBA/isocyanate trimer (Desmodur N 3390) ratio with respect to the hydroxyl group present on the HBA. The performance of the coated specimens was evaluated by various techniques such as pull-off adhesion strength, tensile strength, abrasion resistance, scratch resistance, flexibility, and impact resistance tests. The weathering properties of the coated specimens were evaluated by UV-Weatherometer. Corrosion resistance of the coated specimens was evaluated by electrochemical impedance spectroscopy (EIS), salt spray, seawater immersion and humidity tests. It was observed that, there exists an optimum coating composition in terms of NCO: OH (HBA: Desmodur N 3390) ratio which showed excellent enhancement in terms of the mechanical, weathering and corrosion resistance properties than remaining coating compositions.     

Preparation and characterization of hyperbranched polymer grafted mesoporous silica nanoparticles via self-condensing atom transfer radical vinyl polymerization

Hyperbranched poly(2-((bromobutyryl)oxy)ethyl acrylate) (HPBBEA) was grafted onto the exterior surface of mesoporous silica nanoparticles (MSNs) by surface-initiated self-condensing atom transfer radical vinyl polymerization (SCATRVP). The MSNs with ATRP initiator anchored on the exterior surface (MSN-Br) were prepared by the reaction of 5,6-dihydroxyhexyl-functionalized MSNs (MSN-OH) with α-bromoisobutyryl bromide. Afterwards, MSN-Br was utilized as initiator in the SCATRVP of inimer BBEA, resulting in core-shell nanoparticles with MSN core and HPBBEA shell (MSN-g-HPBBEA). The molecular weight of HPBBEA increased with the increasing ratio of BBEA to MSN-Br. In view of the high density of bromoester groups on the surface of HPBBEA shell, MSN-HPBBEA was used to initiate the successive polymerization of (2-dimethylamino-ethylmethacrylate) (DMAEMA), forming core-shell nanoparticles MSN-g-HPBBEA-g-PDMAEMA. The resultant products were characterized by FT-IR, NMR, HRTEM and thermogravimetric analysis (TGA), etc. The pH-responsive property of MSN-g-HPBBEA-g-PDMAEMA was characterized by measuring the hydrodynamics radius at different pH values, and this core-shell nanostructure may have potential applications in biomedicine and biotechnology.     

Synthesis and characterization of urethane/acrylate composite latex

Polyurethane dispersion and urethane/acrylate composite latex were synthesized and characterized by using a particle size analyzer, gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy coupled with attenuated total reflectance (FTIR‐ATR), dynamic mechanical analysis (DMA), and instron test machine. The amount of solvent and dimethylolpropionic acid (DMPA) used during synthesis of polyurethane resin straightway affected the average particle size and stability of aqueous polyurethane dispersion. The particle size of polyurethane dispersion had nothing to do with that of composite latex. FTIR‐ATR analyses displayed both air‐facing and substrate‐facing surfaces, containing more polyurethane component than the average composition. Some crosslinking reactions occurred in preparing urethane/acrylic composite latex, as indicated by FTIR analyses and solvent extraction. DMA demonstrated three glass transitions for the film from composite latex. Instron tests exhibited better film performance properties for the composite latex than for the corresponding blend latex. A possible particle growth mechanism for preparing urethane/acrylate composite latex was proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1620–1628, 2002; DOI 10.1002/app.10526     

新型超支化环氧丙烯酸酯的合成及表征

采用质子转移聚合法成功制备了超支化环氧树脂,并通过丙烯酸对其端基进行化学改性合成了一种新型的超支化环氧丙烯酸酯,采用FTIR、1H NMR对产物结构进行了表征。通过控制投料比及测定产物酸值来监测反应进行的程度,使生成的超支化环氧丙烯酸酯中既含有环氧基又含有碳碳双键,使之兼具阳离子型光聚合与自由基型光聚合的协同作用。测试了超支化聚合物在氯仿中的紫外-可见光谱和荧光发射光谱,超支化环氧树脂和超支化环氧丙烯酸酯的荧光发射波谱出峰位置分别为314 nm和311 nm。研究表明,超支化聚合物具有较强的荧光性能,作为光固化材料在光学、医疗器件、防伪等领域具有潜在的应用价值。     

Synthesis and characterization of ZnS/hyperbranched polyester nanocomposite and its optical properties

The ZnS/hyperbranched polyester nanocomposite with higher refractive index was prepared by incorporating the acrylated 2-(2-mercapto-acetoxy)-ethyl ester-capped ZnS nanoparticles into the acrylated Boltorn™ H20 (H20). The acrylated 2-(2-mercapto-acetoxy)-ethyl ester-capped colloidal ZnS nanoparticles were synthesized by the reaction of zinc acetate with thioacetamide in N,N-dimethylformamide. The acrylated hyperbranched polyester was obtained by reacting acryloyl chloride with hydroxyl group of H20. The acrylated H20 plays an important role in stabilizing and dispersing ZnS nanoparticles with a diameter of 1-4 nm. The refractive indices of ZnS/hyperbranched polyester nanocomposites, depending on ZnS content, were determined to be in the ranges of 1.48-1.65.     

对叔丁基苯甲酸改性超支化聚酯的合成和性能

以三羟甲基丙烷(TMP)为核,二羟甲基丙酸(bis-MPA)为AB2型单体,合成超支化聚酯(HBPE)。采用对叔丁基苯甲酸(PTBA)对其进行改性,得到PTBA取代度为10%~75%的超支化聚酯(HBP-10M~HBP-75M,统称HBP-Ms)。通过傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1HNMR)和凝胶渗透色谱(GPC)对产物结构和相对分子质量(简称分子量,下同)进行表征,并考察HBP-Ms的溶解性和涂膜性能。研究结果表明,合成了支化度为0.47的HBPE,改性后的HBP-Ms具有良好的溶解性,可溶解在丙酮、DMF、乙酸乙酯、乙醚、苯和二甲苯,不溶于正己烷。HBP-Ms涂膜具有较高的硬度、光泽度和柔韧性,其中HBP-10M和HBP-25M具有更优异的溶解性和涂膜性能。TGA分析表明,PTBA可提高改性树脂涂膜的热稳定性。