Conversion and shrinkage analysis of acrylated hyperbranched polymer nanocomposites

The photo‐curing behavior of composites containing nanosized SiO₂ in an acrylated hyperbranched polymer matrix was investigated by means of photo differential scanning calorimetry. The chemical conversion data were analyzed using an autocatalytic model, paying close attention to the influence of composition and UV intensity. It was shown that the reaction order and the autocatalytic exponent were independent of UV intensity and filler fraction, whereas the rate constant showed strong intensity dependence, but weak filler dependence. Maximum conversion was independent of UV intensity, but was reduced when a filler was present. The dispersion state influenced the gel‐point of the composites, but had no influence on the overall cure kinetics. Cure shrinkage reduction of ～ 33% could be achieved by adding 20 vol% of filler. This was attributed to the reduced double bond conversion of the matrix due to the presence of the filler. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Melt rheology of aliphatic hyperbranched polyesters

Rheological behavior in melt of aliphatic hyperbranched polyesters (AHBP), synthesized using pseudo‐one‐step and one‐step procedure, was investigated in this work. Three commercially available AHBP were also examined. Because of the presence of relatively strong hydrogen bonds between numerous end hydroxyl groups, AHBP of lower generation number, as well as the sample of tenth pseudo generation, show non‐Newtonian behavior in the entire investigated frequency and temperature region. However, for other examined AHBP, the slope of the frequency dependence of complex viscosity (η* = f(ω)) becomes smaller with the temperature increase. Therefore, samples of fourth, fifth, and sixth pseudo generations show Newtonian behavior at temperatures higher than 70°C. Value of glass transition temperature, melt flow activation energy, fractional free volume, and thermal expansion coefficient were determined for the investigated AHBP. The influence of the type of end groups on rheological properties of AHBP was also examined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Photopolymerizable hyperbranched (meth)acrylated poly(amine ester)

A hyperbranched (meth)acrylated poly(amine ester) (HPAE‐2‐A) was synthesized by the modification of the hydroxyl end groups of the second generation of a hyperbranched poly(amine ester) with acryloyl chloride and methacrylic anhydride. The photopolymerization kinetics were investigated with photo‐differential scanning calorimetry and Fourier transform infrared. The properties of HPAE‐2‐A, including the dynamic viscosity, pendulum hardness, and shrinkage, were also studied in comparison with those of a hyperbranched methacrylated poly(amine ester) (HPAE‐2‐MA) prepared in the laboratory and traditional epoxy acrylate and epoxy methacrylate. HPAE‐2‐A polymerized rapidly under UV irradiation in the presence of a photoinitiator and had a higher final conversion of double bonds. The thermomechanical properties of UV‐cured HPAE‐2‐MA films were compared with those of EB‐cured films measured with a dynamic mechanical thermal analyzer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 168–173, 2003     

Dyeing kinetics of methacrylic acid grafted polyester fabric with astrazonrot violet and rhodamine red basic dyes

The low‐temperature dyeing kinetics of radiation‐grafted poly(ethylene terephthalate) fabric were studied. The effects of the graft yield (GY), dye concentration, and dyeing temperature on the color difference (CD) of methacrylic acid grafted polyester fabric were studied for astrazonrot violet (AV) and rhodamine red (RR) basic dyes. CD increased sharply with an increase in GY and tended to level off at higher degrees of grafting. The best dyeing conditions were achieved for both dyes at pH 11.5. CD of the grafted fabric increased rapidly as the dyeing time increased; this was followed by a relatively slow dyeing rate within a few minutes, which depended on the concentration and temperature of the dye bath. The initial dyeing rates and rate constants for the AV dye were higher than those for the RR dye. The dyeing process followed 0.14‐order kinetics and was independent of the dyeing temperature or the type of dye. The dyeing rates and rate constants increased with an increase in the dyeing temperature. An Arrhenius‐type plot of the natural logarithm of the dyeing rate constant versus the inverse of the absolute temperature yielded apparent activation energies of 4.9 and 13.8 kJ/mol and pre‐exponential rate constants of 9.4 and 100.6 (CD/GY)s^?1 for the AV and RR dyes, respectively. The mechanism of the dyeing process for the two dyes was diffusion‐controlled, and their dyeing rates depended on the type of basic dye. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1070–1076, 2004     

Rheological behavior in the molten state and solution of hyperbranched polyester of fourth and fifth generation

The rheological behavior in the molten state and solution of hyperbranched polyol polyesters (HBPs) obtained by one step (HBP4, HBP5), step by step (HBP4P, HBP5P), and combination of both (HBP1‐4, HBP1‐5) was studied. Under conditions of dynamic oscillatory shear, all HBPs presented a shear‐thinning behavior and under steady shear they showed a Newtonian behavior. Also, the steady shear viscosities decreased with increasing temperature. The behavior of HBPs was mainly viscous, except for the HBP4P that showed higher storage modulus and reduction of complex viscosity when increasing the angular frequency. The HBPs presented higher complex viscosity than steady shear and they did not follow the Cox‐Merz rule. The HBPs in solution presented a plateau region at shear rate lower than 40 s⁻¹ but a shear‐thickening behavior at shear rate higher than 40 s⁻¹. The viscosities of HBPs in solution (in the plateau region) and molten state increase in the following order: HBP5P > HBP1‐5 > HBP4P > HBP1‐4 > HBP4 > HBP5. These results are not in agreement with the values of the number average molar mass obtained by vapor pressure osmometry due to different interaction between HBPs molecules. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of a thermotropic liquid crystalline hyperbranched polyester

BACKGROUND: Hyperbranched polymers have received increasing attention in the fields of medicine, homogeneous catalysis and materials science. Hydroxyl‐functional aliphatic polyesters are one of the most widely investigated families of hyperbranched polymers. The research reported here is based on the preparation of a novel hyperbranched polyester and the modification of its terminal hydroxyl groups by biphenyl mesogenic units. RESULTS: 2,2,6,6‐Tetramethylolcyclohexanol as a core and 8‐[4′‐propoxy(1,1‐biphenyl)yloxy]octanoic acid as a mesogenic unit were synthesized. A hyperbranched polyester (HPE) was synthesized in one step and subsequently substituted by reaction of its terminal hydroxyl groups with the biphenyl mesogenic units to yield a novel liquid crystalline hyperbranched polyester (HPE‐LC). The chemical structures of all compounds were confirmed using Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopy. The thermal behavior and the mesogenic properties of the biphenyl mesogenic unit and HPE‐LC were investigated using differential scanning calorimetry, polarized optical microscopy and wide‐angle X‐ray diffraction. The results demonstrated that the degree of branching of the HPE is ca 0.63. Both HPE‐LC and the biphenyl mesogenic unit exhibit mesomorphic properties, but HPE‐LC has a lower isotropic transition temperature and a wider transition temperature range than the biphenyl mesogenic unit. CONCLUSION: A novel liquid crystalline hyperbranched polyester was successfully synthesized, which exhibits mesomorphic properties. This polymer has good solubility in highly polar solvents and good thermal stability. Copyright © 2009 Society of Chemical Industry     

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     

Lipase-catalyzed synthesis of hyperbranched polyester improved by autocatalytic prepolymerization process

This work developed a facile and environmentally friendly route for lipase-catalyzed synthesis of a hyperbranched polyester by introducing an autocatalytic prepolymerization of comonomers. Trimethylolpropane, 1,8-octanediol, and adipic acid as comonomers for synthesizing the hyperbranched polyester were first prepolymerized via the automatic catalytic effect of the reactants themselves to obtain an appropriate reaction substrate for further lipase-catalyzed polymerization, where immobilized lipase Novozym 435 was used as a biocatalyst. The acidity and fluidity of optimized oligomers after the autocatalytic prepolymerization provide a benign reaction substrate for the retention of enzymatic activity in the subsequent lipase-catalyzed esterification, which is crucial for the enzymatic polymerization. The optimum reaction temperature and reaction time for prepolymerization were determined to be 120 °C and 150 min. The molecular weight (M _w) of the prepared polyester was approximately 26,300 g/mol. Quantitative analysis of ¹H-NMR and inverse-gated ¹³C-NMR spectra confirmed the hyperbranched structure of the resulting polyester with a branching degree of 31.3%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47221.     

Thermal degradation kinetics of polyesters containing mesogenic aromatic diols

A series of polyesters were synthesized by reacting structurally differing aromatic diols with either saturated (flexible) or unsaturated (rigid) dicarboxylic acid halide by a stirred interfacial polycondensation technique. Thermal degradation kinetics of these polyesters were investigated by applying Coats–Redfern and Horowitz–Metzger nonisothermal procedures. The dynamic thermogravimetry experiments were conducted in nitrogen to obtain differential thermogravimetric plots. Thermal stability of these polyesters was discussed on the basis of semiquantitative methods such as differential procedural decomposition temperature, integral procedural decomposition temperature, and fraction decomposition temperature (e.g., 10% DT). Degradation proceeded in multiple stages. The thermal degradation patterns and activation energies in these stages were discussed in relation to central bridging moieties of aromatic diol. The activation energies of these polyesters were found to be in the range of 100 to 200 kJ/mol. The effect of spacer type on activation energy was also reported. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 784–792, 2005     

超支化聚酯共混聚合物等温结晶动力学研究

采用三羟甲基丙烷、2,2-二羟甲基丙酸、对甲苯磺酸反应制备第2～5代超支化聚酯(HBP),将其按质量分数10%分别与聚丙烯(PP)和聚甲醛(POM)共混,用差示扫描量热法(DSC)研究了共混物的等温结晶动力学。结果表明,用Avrami方程描述PP/HBP和POM/HBP的结晶动力学较理想。在PP中,HBP主要起成核作用;在POM中,HBP主要起稀释作用;第2代HBP成核作用最弱,稀释作用最强,第5代HBP稀释作用最小。     

Enzymatic degradation of hyperbranched polyesters

In this work, the enzyme‐catalyzed degradation of hyperbranched polyesters (HBPEs) was investigated. Enzymatic degradation experiments were performed in a phosphate buffer in the presence of the lipases Candida cylindracea, Pseudomonas cepacia, Novozym 388, Amano CE, Lipomod 34P, and Cal‐B, whereas control experiments were performed in the same system without lipases. The extent of polymer degradation was determined by quantification of the released free fatty acids by gas chromatography. The influence of the alkane chain length and the number of alkane chain end groups on the lipase‐catalyzed hydrolysis of esterified HBPEs was investigated systematically. It was found that the increase in the alkane chain length of the end groups diminished the enzymatic degradation of the polymer, whereas the number of end groups had no influence on the degradation rate. The effect of temperature on the rate of degradation was also described. Surface morphological changes that occurred during the degradation were assessed with reflected electron microscopy. The changes in the crystallinity of the polymers after they were subjected to degradation were qualitatively determined with differential scanning calorimetry through the quantification of the enthalpy of melting. The enthalpy of melting of one HBPE sample increased from 79 to 90 and 94 J/g with and without the action of Lipomod 34P, respectively, in 7 days, showing the changes in the crystallinity of the polymer. The results prove that modified HBPEs are an important new class of biodegradable materials with a predictable degradation mechanism, and the degradation can be adjusted on the basis of the molecular engineering. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of printable solder resist inks based on hyperbranched polyester

Two novel solder resist inks containing hyperbranched epoxy resin (HBPE) for thermal curing and hyperbranched epoxy acrylate resin (HBPEA) for UV‐curing were introduced in this work. Different generations of HBPE and HBPEA were synthesized and their chemical structures were determined by FT‐IR. Both curing reactions were monitored under differential scanning calorimetry (DSC) and photo‐DSC. For HBPE, the curing temperature of 7th generation was only 91°C and for HBPEA, the curing duration of 7th generation was under 10 s. The thermal stabilities of cured resins were much more stable than linear resin, as the decomposition temperatures of HBPE and HBPEA were both over 400°C. The ink containing HBPE or HBPEA jetted by piezoelectric printer showed excellent accuracy and consistency of linewidth and the morphologies of cured pattern were observed through a stereo microscope. Other performances of solder masks were tested under China Printed Circuit Association (CPCA) standard (CPCA/JPCA 4306‐2011), which satisfy all requirements of printed circuit board soldering procedure. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41805.     

Cationic photopolymerization of oxetane‐functionalized hyperbranched polymers

An aliphatic–aromatic pehenolic hyperbranched starting material (HBP‐OH) with phenolic end groups was 85% functionalized by a Mitsunobu reaction with oxetane groups (OXT‐HBP). This new hyperbranched polyester was used, at a concentration of 5–20 wt %, as an additive for the cationic photopolymerization of a commercial oxetane‐based resin, 4,4′‐bis[(3‐ethyl‐3‐ethyl‐3‐oxetanyl) methoxymethyl]biphenyl (OXBP). HBP‐OXT acted as a multifunctional crosslinker, copolymerizing with the oxetane ring of the OXBP resin, reacting through chain transfer with the remaining phenolic OH groups, or doing both. The result was an increase in the glass‐transition temperature due to the increase in the crosslinking density. An increase in the weight residue at a high temperature was found in the presence of HBP‐OXT and was attributed to the presence of phenolic groups, which are commonly used as antioxidant additives. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 293–299, 2005     

Radiation curing of hyperbranched polyester resins

A research area that has obtained increasing interest during the last decade concerns improvement of macromolecular properties by changes in the macromolecular architecture. One group of these materials is dendritic polymers, which are highly branched structures exhibiting very different properties compared with linear polymers. One potential application for these polymers is as radiation curable thermoset resins. This article describes a study where the use of an aliphatic hyperbranched polyester as a base for new radiation curable thermoset resins. The hyperbranched polyesters have been characterized with respect to cure rate and final mechanical properties compared with conventional resins. It is shown that hyperbranched polyesters can be used as versatile scaffolds for various radiation curable resin structures. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 612–618, 2000     

Preparation of hyperbranched polyester photoresists for miniaturized optics

Hyperbranched polymers containing carboxyl and acryloxyl groups were prepared through a one‐step synthesis with metatrimellitic anhydride, epichlorohydrin, and methylacrylic acid glycidic ester. The photo‐sensitivity coefficients of the polymer resists varied with the resin acid values and formulas. The linear depth was the reverse of the contrast. When the contrast was less than 0.49, the linear depth could reach 43 μm. The hyperbranched polyester resists were used to prepare microlens arrays. Moreover, there was a slight discrepancy between the element profile and simulated profile of the formed resists. The etching depth could reach 50 μm. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1259–1263, 2004     

Improving the heat‐resistance and toughness performance of phenolic resins by adding a rigid aromatic hyperbranched polyester

An aromatic hyperbranched polyester (AHBP) was synthesized by melt polycondensation from diphenolic acid and characterized by Fourier transform infrared spectrum (FTIR) spectra. The degree of branching (DB) value of AHBP calculated from the ¹³C‐NMR spectroscopy was 0.67. The number‐average molecular weight (M_n) and weight‐average molecular weight (M_w) of AHBP were 1792 and 4480 g/mol, respectively. Novel phenolic resins modified with AHBP (PR/AHBP) were then prepared, in which AHBP was used as toughener of phenolic resins. The effect of AHBP on the thermal properties of phenolic resins was studied by means of differential scanning calorimetry (DSC), thermal gravimetric analyses (TGA), and heat deformation temperature tests. The modified resins presented higher glass transition temperature (T_g) than the unmodified system due to that the rigid backbone structure of AHBP with a great deal of the benzene ring groups restricted the mobility of the chain segments of macromolecules. The DSC, scanning electron microscopy (SEM) analyses showed that AHBP had good compatibility with phenolic resin, and the modified resins showed ductile fracture. The results of mechanical performance measurements exhibited that the impact strength of PR/AHBP containing 15 wt % AHBP was about 130% higher than that of the neat phenolic resin, suggesting that the toughness of PR/AHBP was significantly improved by the addition of AHBP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42734.     

Photopolymerization kinetics of cycloaliphatic epoxide–acrylate hybrid monomer

An epoxide–acrylate hybrid monomer was synthesized by the controlled reaction of a cycloaliphatic epoxide and acrylic acid. The photopolymerization kinetics was investigated using a real‐time infrared spectroscopy technique. The influences of photoinitiator concentration, free radical initiator and polymerization atmosphere on the polymerization were studied. The hybrid monomer showed unique photopolymerization kinetics in the photopolymerization process and the final conversions of epoxy groups and acrylate double bonds were improved synchronously. Dynamic mechanical analysis results demonstrated that the hybrid monomer cured film formed a more uniform polymer network than the blend of epoxy acrylate and epoxide. Copyright © 2007 Society of Chemical Industry     

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。     

松香基UV固化超支化聚酯丙烯酸酯的合成

采用季戊四醇作为聚酯内核与二羟甲基丙酸(DMPA)发生酯化反应后,再与以松香为原料合成的马来海松酸酐(MPA)反应合成富含末端基团的超支化聚酯大分子(HBP),再分别将2-羟乙基丙烯酸酯(2-HEA)和五缩六乙二醇丙烯酸单酯(PEA-6)引入到HBP结构中,得到新型UV固化超支化树脂(HBR)。采用红外光谱对产物结构进行了表征,对固化膜进行了热重分析,通过动态力学谱测试了其粘弹性,并对涂膜的其他基本性能进行了测定。结果表明,所得树脂大都具有较低的粘度,漆膜硬度较好,对金属、塑料底材附着力较好。随着PEA-6用量的增加,产物的硬度和热力学稳定性能下降,柔韧性增加。     

表面活性单体DMBAC光聚合动力学研究

采用偶氮二异丁脒盐酸盐(AIBA)作为光引发剂,光引发聚合并研究了阳离子表面活性单体——甲基丙烯酰氧乙基二甲基苄基氯化铵(DMBAC)的均聚及其与丙烯酰胺(AM)共聚合反应的动力学行为,聚合反应均在高于DMBAC临界胶束浓度(CMC)的条件下进行.研究结果显示DMBAC均聚合反应速率与引发剂浓度的0.29次方以及单体浓度的0.89次方成正比,均聚合反应的表观活化能约为13.74 kJ/mo1;DMBAC与AM共聚合反应速率与引发剂浓度的0.82次方以及单体总浓度的0.83次方成正比,共聚合反应的表观活化能约为10.97 kJ/mo1;同时测得DMBAC与AM共聚合反应的单体竞聚率为r1=0.27(AM)、r2=2.00(DMBAC),说明AM趋向于形成共聚物,而DMBAC更趋向于形成均聚物.