New coating systems based on vinyl ether‐ and oxetane‐modified hyperbranched polyesters

A series of hyperbranched aliphatic‐aromatic polyesters has been synthesized which contain vinyl ether or oxetane functionalities as curable groups. We investigated the curing behavior of these multifunctional polymers in the presence of reactive diluents in order to analyze the possibility of their application in high solids coatings. The vinyl ether‐modified hyperbranched polyesters with a high degree of modification yield the best coatings. Furthermore, coating systems containing vinyl ether‐modified hyperbranched polyesters and triethyleneglycol divinyl ether (DVE‐3) as reactive diluent showed a better performance compared to those containing 4‐hydroxybutyl vinyl ether (HBVE). Real time FT‐IR studies revealed a high conversion of functional groups (76%) for the cationic curing with DVE‐3. On the other hand, the curing reaction of the functional hyperbranched polymers without the presence of any reactive diluent stopped at 32% conversion of functional groups due to the reduced mobility of the polymer. The vinyl ether‐modified hyperbranched polyester could be cured also radically in the presence of diethyl maleate (DEM) as reactive diluent, whereas the curing of the oxetane‐modified polyesters was very slow and incomplete in all attempts.     

Hydrogen‐bond acidic polyhedral oligosilsesquioxane filled polymer coatings for surface acoustic wave sensors

A series of novel polyhedral oligosilsesquioxane nanofiller compounds functionalized with hydrogen‐bond acidic sensor groups was prepared, characterized by IR, ¹H‐, ¹³C‐ and ²⁹Si‐NMR, and MALDI‐TOF MS, and formulated into polymer coatings for 500 MHz surface acoustic wave sensor platforms. Sensor responses to the explosives simulant dinitrotoluene and to the nerve agent simulant dimethyl methylphosphonate were studied, and the performances of the polyhedral oligosilsesquioxane formulations were compared with those of conventional hydrogen‐bond acidic linear surface acoustic wave sensor polymers carrying the same sensor groups. The polyhedral oligosilsesquioxane formulations gave good initial responses to the simulants, maintained 40–65% of their original response over a period of 6 months and maintained their sensitivity down to a simulant vapor concentration of 1 ppb v. The surface compositions of the surface acoustic wave sensor coatings were characterized by sum frequency generation spectroscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

氢键酸性接枝聚硅氧烷的合成及应用

应用硅氢化反应将具有氢键酸性的间三氟甲基苯酚接枝在聚甲基氢硅氧烷上,合成了一种用于有机磷化合物检测的新型氢键酸性敏感材料,并通过IR、1HNMR、GPC和GC-MS进行表征.在此基础上,制备了声表面波(SAW)气体传感器,并对甲基膦酸二甲酯(DMMP)进行了检测,效果良好.     

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     

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     

Aliphatic hyperbranched polyesters based on 2,2-bis(methylol)propionic acid—Determination of structure, solution and bulk properties

Due to their highly branched structure and the large number of functional groups hyperbranched polymers possess unique properties that make them interesting for uses in a wide variety of applications. Some of the most widely investigated hyperbranched polymers are the polyesters based on 2,2-bis(methylol)propionic acid. In this paper we present the results of characterization studies of hyperbranched polyesters based on 2,2-bis(methylol)propionic acid which show that they are very complex products with a multidimensional distribution of various properties. The influence of the synthesis conditions on the structure and molar-mass characteristics of hyperbranched polyesters as well as the findings that allow a thorough understanding of the structure-property relationships are reviewed in detail.     

Rheology of concentrated solutions of hyperbranched polyesters

The solution rheology of different generations of hyperbranched polyesters in N‐methyl‐2‐pyrrolidinone (NMP) solvent was examined in this study. The solutions exhibited Newtonian behavior over a wide range of polyester concentrations. Also, the relative viscosities of poly(amidoamine) (PAMAM) dendrimers in ethylenediamine were compared with those of the hyperbranched polyesters in NMP. Both types of dendritic polymers have relative viscosities that are exponential functions of their molar fraction in solution. The slopes of these relative viscosity curves show a linear relationship with respect to the generation number. PAMAM dendrimers have the greater slopes for each generation, reflecting their relatively larger intrinsic viscosity values.     

The effect of hyperbranched polymers on processing and thermal stability of biodegradable polyesters

Nanomodification of poly‐hydroxy‐butyrate (PHB), with hyperbranched polymers (HBP), was studied. Solid‐hyperbranched polyesters of different generations were incorporated into a biobased and biodegradable, thermoplastic, polyester. Thermal, rheological, and molecular weight measurements had indicated that due to the interactions between the hydroxyl groups and the polar esters in PHB, the rate of recrystallization was significantly increased. Furthermore, the degree of crystallinity and nonisothermal crystallization temperature were also increased. Molecular weight measurements did not indicate a reduction or retention when HBPs were incorporated. These results are of great significance for the processing of biodegradable polymers and specifically for PHB, where improved processability and enhanced crystallization are of importance. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Chemical structure of poly(β‐cyclodextrin‐co‐citric acid)

We synthesized water‐insoluble polymers, poly(β‐cyclodextrin‐co‐citric acid)s, by heating a mixture of citric acid, cyclodextrin (CD), and Na₂HPO₄ as a catalyst with a 6 : 1 : 2 molar ratio at 160, 170, and 180°C for 10 and 20 min. The chemical composition of the polyesters was determined by high pressure liquid chromatography (HPLC) analysis of the polymer hydrolysates. The crosslinking mechanisms and thermal degradation of the polymers were also investigated. The polyesters contained 30–35% citric acid, 1–4% unsaturated carboxylic acids (i.e., itaconic, cis‐aconitic, trans‐aconitic, and mesaconic acids), and 60–70% CD, whereas about 40% of them were able to form inclusion complexes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

核分子比例对超支化聚酯结构和涂膜性能的影响

以双季戊四醇为核,二羟甲基丙酸为单体合成了不同代数的超支化聚酯。采用了IR、GPC、13C NMR、DSC和化学滴定等方法对产物进行了表征和分析。试验结果表明聚合物具有较小的多分散性指数(拟两代超支化聚酯M—w/M—n=1.159,拟四代超支化聚酯M—w/M—n=1.028)。通过聚合物的13C NMR分析了超支化聚酯的支化度,表明在超支化聚酯中,端羟基的反应活性大于线性单元中羟基的活性。并用油酸对聚合物进行改性,研究了固含量与黏度的关系及其涂膜的性能;结果表明该树脂具有良好的成膜性和涂膜性能。     

Ionic polymers with tunable liquid‐crystalline properties

Side‐chain polyesters were synthesized from N‐octyl‐, N‐dodecyl‐ or N‐hexadecyl‐diethanolamine and succinic acid anhydride. These polyesters were then transformed into polyester hydrochlorides by protonation of the amino groups using different amounts of HCl (20–100 mol%). Above 60 mol% the reaction is not quantitative and a degree of protonation of up to 88% is obtained. The structures of the synthesized polyesters and their hydrochlorides were determined by ¹H nuclear magnetic resonance spectroscopy. The thermal properties of the synthesized polyesters and their hydrochlorides were also studied using differential scanning calorimetry in relation to the side‐chain length and the degree of polyester protonation. The polyester with octyl side chains and its hydrochlorides were amorphous liquids at room temperature, while the polyester and polyester hydrochlorides with hexadecyl side chains formed a smectic crystalline phase, S_mB, or its tilted analogues. The polyester with a dodecyl side chain was also an amorphous liquid at room temperature, while its hydrochlorides with various degrees of protonation were smectic liquid crystals, as determined by X‐ray diffraction. By simply varying the degree of protonation the liquid crystal isotropization temperature was increased from 32 °C to 82 °C. Copyright © 2011 Society of Chemical Industry     

Study of negative substitution and monomer self‐condensation effects on molar mass and structural characteristics of hyperbranched polyesters originating from a high‐functionality core

In order to provide more insight into the effect of core functionality on hyperbranched polymer characteristics, two series of hyperbranched polyesters (HBPEs) were synthesized by reacting 2,2‐bis(methylol)propionic acid (bis‐MPA) as AB₂ monomer with both dipentaerythritol (DPE) and pentaerythritol as six (B₆)‐ and four (B₄)‐functional core molecules. The molar mass, composition and structure of HBPEs were determined with respect to the negative substitution logic and monomer self‐condensation effect. The molar masses and structures of HBPEs containing DPE core were less influenced by the negative effect of a reacted hydroxyl group on the reactivity of other hydroxyl groups in the same monomer unit. Thus, the use of DPE core in copolymerization with bis‐MPA monomer could help slightly to increase the molar mass of HBPEs. Conversely, the effect of self‐condensation of bis‐MPA on the molar mass reduction was more pronounced in the case of DPE hyperbranched polymers due to the A–B negative substitution effect. These two effects become more significant with increasing pseudo‐generation numbers of the HBPEs. © 2014 Society of Chemical Industry     

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.     

Reactions and polymerization of hexa‐[3‐tert‐butyl‐4‐ hydroxyphenoxy]cyclotriphosphazene: A new method for the preparation of soluble cyclomatrix phosphazene polymers

Novel cyclomatrix phosphazene‐containing polyester polymers were synthesized through the reaction of a polyhydroxylated cyclotriphosphazene and a bifunctional acid chloride. To demonstrate the chemistry of the free hydroxyl of hexa‐[3‐tert‐butyl‐4‐hydroxyphenoxy]cyclotriphosphazene, nucleophilic displacement reactions were performed with both acetic anhydride and alkyl chlorides. This work compares favorably to literature data for the chemistry of hexa‐[4‐hydroxyphenoxy]cyclotriphosphazene, whose hydroxyl is not hindered by an adjacent substituent. The hindered site of hexa‐[3‐tert‐butyl‐4‐hydroxyphenoxy]cyclotriphosphazene was found to react with bidentate acid chlorides to yield new high polymers. The phosphazene‐containing polyesters were observed to have good solubility in polar organic solvents. Characterization of these new materials was performed using dilute solution laser light scattering techniques, thermal analysis, and NMR spectroscopy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 242–251, 2001     

Phase behaviour of hyperbranched polyesters and polyethers with modified terminal OH groups in supercritical solvents

Hyperbranched polyethers and polyesters have been synthesized, and their phase behaviour in carbon dioxide and light hydrocarbons explored as a function of concentration and temperature. The synthesis includes modifications of the terminal OH groups with aliphatic carboxylic acids derivatives, trimethylchlorosilane, and trifluoroacetic acid anhydride. Modified polyesters show good solubility in carbon dioxide, ethane and propane. The comparison with the literature data shows that the silane and fluorinated derivatives of the hyperbranched polyesters are soluble in carbon dioxide to the same extent as the most CO₂-philic polymeric materials synthesized till now. It seems that the nature of the end groups is an important factor that influences phase equilibria of hyperbranched macromolecules in supercritical solvents. However, the nature of the interior of the macromolecule is also significant. The results obtained show that in general hyperbranched polyesters are better soluble in carbon dioxide than hyperbranched polyethers. In light hydrocarbons as solvents the opposite effect is observed.     

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     

Biodegradable polymers based on renewable resources. IV. Enzymatic degradation of polyesters composed of 1,4:3.6‐dianhydro‐D‐glucitol and aliphatic dicarboxylic acid moieties

Enzymatic degradation of a series of polyesters prepared from 1,4:3.6‐dianhydro‐D ‐glucitol (1) and aliphatic dicarboxylic acids of the methylene chain length ranging from 2 to 10 were examined using seven different enzymes. Enzymatic degradability of these polyesters as estimated by water‐soluble total organic carbon (TOC) measurement is dependent on the methylene chain length (m) of the dicarboxylic acid component for most of the enzymes examined. The most remarkable substrate specificity was observed for Rhizopus delemar lipase, which degraded polyester derived from 1 and suberic acid (m = 6) most readily. In contrast, degradation by Porcine liver esterase was nearly independent of the structure of the polyesters. Enzymatic degradability of the polyesters based on three isomeric 1,4:3.6‐dianhydrohexitols and sebacic acid was found to decrease in the order of 1, 1,4:3.6‐dianhydro‐D ‐mannitol (2), and 1,4:3.6‐dianhydro‐L ‐iditol (3). Structural analysis of water‐soluble degradation products formed during the enzymatic hydrolysis of polyester 5g derived from 1 and sebacic acid has shown that the preferential ester cleavage occurs at the O(5) position of 1,4:3.6‐dianhydro‐D ‐glucitol moiety in the polymer chain by enzymes including Porcine pancreas lipase, Rhizopus delemar lipase, and Pseudomonas sp. lipase. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 338–346, 2000     

Flame‐retardant polyesters. II. Polyester polymers

Two flame‐retardant polyesters were polymerized with two types of phosphorous flame retardants. 3‐(Hydroxyphenyl phosphinyl)propanoic acid (HPP) was used as a main‐chain type, and 9,10‐dihydro‐9‐oxa‐10‐2,3‐dicarbonylpropyl‐10‐phosphophenanthrene‐10‐oxide (DI) was used as a pendant type. Polymerization was accomplished on a commercial scale with a three‐reactor system to exclude the compositional variation of oligomeric ethylene terephthalate. A longer polycondensation time and a higher dosage of the catalyst were necessary for DI with respect to HPP because of the high content and relatively low reactivity of the flame retardant. However, the content of diethylene glycol (DEG) in the polyester, which formed during the polymerization, was much higher in the case of HPP. The produced polyesters had almost the same molecular weight, but the DEG contents in the polyesters were quite different. The higher DEG content in the HPP polyester reduced the thermal stability. The greater flexibility of the HPP polyester chain resulted in easier crystallization and a lower crystalline temperature. The HPP polyester had higher susceptibility to thermal degradation because of low resistance to thermal chain scission, degraded at a lower temperature, and was more easily degraded because of a weak P? O bond linkage in the main chain. The DI polyester, whose phosphorous atom was highly sterically hindered, showed better alkaline resistance than the HPP polyester because of the lower acidity and lower hydrophilic DEG content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

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).