Synthesis and properties of new polyurethane ionomers. I. Photosensitive cationomers with triazene units

New bifunctional triazene compounds 1‐(m‐ hydroxymethyl)phenyl‐3‐(2‐hydroxyethyl)‐3‐methyltriaz(1)ene and l‐p‐nitrophenyl‐3,3‐di(2‐hydroxyethyl)triaz(1)ene as intermediates in polyurethane synthesis were prepared. Photosensitive polyetherurethane cationomers based on poly(tetramethylene oxide) diol of 2,000 average molecular weight, tolylene‐2,4‐diisocyanate, and N‐methyldiethanolamine/triazene diols, as cochain extender, followed by a quaternization with benzyl chloride, were synthesized and characterized. Upon UV irradiation, feniltriazene chromophore in monomer and both polymers (ionomeric or nonionomeric type) is irreversibly cleaved, as evidenced in photolytic and kinetic studies. The rate constant of photolysis in ionomer film was lower than for the corresponding nonionic film. A positive pattern can then be developed by treatment with CHCl₃ that dissolves the exposed zone, while the unexposed area remains resistant and insoluble. By incorporating side nitrofeniltriazene groups, photostable polyurethanes were obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1203–1210, 2003     

Synthesis and properties of new polyurethanes with triazene moieties in the main chain

A new diol with bistriazene groups, 1,1′[4,4′‐diphenylether]‐3,3′‐di(β‐hydroxyethyl methyl)‐bistriazene (BTD), was synthesized and characterized. BTD, along with N‐methyldiethanolamine as a chain extender, was used to prepare a segmented polyurethane based on poly(tetramethylene oxide) diol (weight‐average molecular weight = 2000) and 2,4‐tolylene diisocyanate (80:20 v/v 2,4‐/2,6‐isomer mixture). Subsequent quaternization of the amine with benzyl chloride formed the cationomer. The structure–property relationships, including the photochemical behavior of the triazene linkage in these polymers, were investigated with respect to another polyurethane prepared from 4,4′‐diphenylmethane diisocyanate and a bistriazene compound. Photolysis experiments were carried out in polymer solutions and in the film state, and the reduction of the π–π* absorption band, characteristic of the triazene chromophore in ultraviolet spectra, was followed. A kinetic evaluation revealed a first‐order photoprocess. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 385–391, 2005     

脂肪族聚氨酯二丙烯酸酯的合成与性能研究

以聚己内酯二醇、3-异氰酸酯基亚甲基-3,5,5-三甲基环己基异氰酸酯、丙烯酸羟乙酯为原料合成脂肪族聚氨酯二丙烯酸酯。实验结果表明,预聚物64份,四氢呋喃丙烯酸酯30份,γ-缩水甘油醚基丙基三甲氧基硅烷1份,1-羟基环己基苯基甲酮3份,纳米二氧化硅2份配制的UV胶,具有较佳的力学性能、耐热、耐湿热性能,综合性能接近loctite3106。     

Effective preparation and characterization of montmorillonite/poly(ε‐caprolactone)‐based polyurethane nanocomposites

In this study, montmorillonite (MMT)/poly(?‐caprolactone)‐based polyurethane cationomer (MMT/PCL‐PUC) nanocomposites were prepared and their mechanical properties, thermal stability, and biodegradability were investigated. PCL‐PUC has 3 mol % of quaternary ammonium groups in the main chain. The MMT was successfully exfoliated and well dispersed in the PCL‐PUC matrix for up to 7 wt % of MMT. The 3 mol % of quaternary ammonium groups facilitated exfoliation of MMT. The 1 wt % MMT/PCL‐PUC nanocomposites showed enhanced tensile properties relative to the pure PCL‐PU. As the MMT content increased in the MMT/PCL‐PUC nanocomposites, the degree of microphase separation of PCL‐PUC decreased because of the strong interactions between the PCL‐PUC chains and the exfoliated MMT layers. This resulted in an increase in the Young's modulus and a decrease in the elongation at break and maximum stress of the MMT/PCL‐PUC nanocomposites. Biodegradability of the MMT/PCL‐PUC nanocomposites was dramatically increased with increasing content of MMT, likely because of the less phase‐separated morphology of MMT/PCL‐PUC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Clear polyurethane dispersions of nanometer size derived from carboxylic polycaprolactonediols

Aqueous polyurethanes dispersions of nanometer size derived from various carboxylic polycaprolactonediols of different molecular weights, carboxylic diols, including 2,2‐di(hydroxymethyl)propanoic acid (DMPA), 2,2‐di(hydroxymethyl)butanoic acid (DMBA), and di(4‐isocyanatocyclohexyl)methane (HMDI) were prepared by a method in which the dispersing procedure was modified to enhance the molecular weight. The molecular weight, particle size, and UV–vis spectra of the polyurethane dispersions were investigated. The tensile properties of the cast films were determined. The modified dispersing procedure gave polyurethane dispersions with higher molecular weight and better tensile strength. As the molecular weight of the carboxylic polycaprolactonediol decreases, the content of the ionic groups increases, the particle size decreases accordingly. As the molecular weight of the carboxylic polycaprolactonediol used is 1000 g/mol or below, the polyurethanes dispersions become completely clear. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and optical performance of chiral polymers having azobenzene segments

A series of monomeric azobenzene derivatives of 6‐(4‐nitro‐4′‐oxy‐azobenzene acrylate with carbon numbers of 6 and 11, and the chiral monomer of bornyl 4‐(6‐acryloyloxyhexyloxy)‐phenyl‐4′‐benzoate were synthesized. Chiral polymers having bornyl group end‐capped pendants with azobenzene‐derived segments were prepared. Molecular structures and polymer compositions were confirmed by using ¹H‐NMR, elemental analysis, FTIR, and UV–vis analyzers. Thermodynamic properties of both monomers and polymers were investigated. Specific rotations of chiral monomers and polymers were estimated by using an automatic digital polarimeter. Liquid crystalline textures of monomers and polymers were analyzed by using a polarizing optical microscope and confirmed by a small‐angle X‐ray analyzer. The optical reflection characteristics of composite cells with chiral nematic liquid crystal and various amounts of azobenzene derivatives were evaluated by using a UV–vis spectrophotometer. The reliability and stability of the composite cells with E48/S811 and azobenzene derivatives were studied. The photoisomerization of the chiral polymer film was investigated by using SEM and AFM analyzers. It was found that the UV irradiation of a laser spot caused the shrinkage of polymer film due to the photoisomerization of azobenzene segments. The contraction of the polymer film can be recovered by heat treatment. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3693–3704, 2004     

Hydroxyl‐functional polyurethanes and polyesters: synthesis,properties and potential biomedical application

This mini review gives an overview of the synthesis of polyurethanes and polyesters with pendant hydroxyl groups performed mainly in our group. Significant for the synthesis of most of these polymers with hydroxyl‐functional side groups is that no protection groups are needed. This is realised either by generating the OH group during polymer synthesis—demonstrated by the preparation of hydroxyl‐functional polyurethanes from dicarbonate monomers and diamines—or by using catalysts which discriminate between primary and secondary OH groups—demonstrated by the synthesis of hydroxyl‐functional polyesters based on malic acid using scandium triflate as catalyst. In addition, the potential of carbonate couplers for the synthesis of multifunctional polyurethane is presented. The application of such multifunctional polyurethanes as antimicrobial polymers and coatings is briefly discussed. Copyright © 2012 Society of Chemical Industry     

Novel method for preparation of polyurethane elastomers with improved thermal stability and electrical insulating properties

A novel method was developed for the preparation of polyurethane with enhanced thermal stability and electrical insulation properties via the reaction of epoxy‐terminated polyurethane prepolymer (EPU) and poly(amic acid) (PAA). EPUs were synthesized from the reaction of glycidol with NCO‐terminated polyurethane prepolymers, which were prepared from the reaction of polycaprolactone‐based polyol (CAPA) of different molecular weights and some commercially available diisocyanates including hexamethylene diisocyante, toluene diisocyanate, and 4,4′‐methylene bis(phenyl isocyanate). PAA was prepared from the reaction of equimolar amounts of pyromellitic dianhydride and oxydianiline. The effects of PAA content, the nature of diisocyanate, and the molecular weight of CAPA on the mechanical, thermal, thermomechanical, and electrical properties of the final networks were investigated. The crosslink density of the samples was determined according to an equilibrium swelling method using the Flory–Rehner equation and was correlated to the structure of the final polymers. Gel content and activation energy of network formation in the absence and the presence of a tertiary amine catalyst were also studied. The results showed considerable improvement in the thermal, electrical, and mechanical properties compared to those of other common polyurethanes. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1776–1785, 2007     

A novel method to control microcapsule release behavior via photo‐crosslink polyurethane acrylate shells

A microcapsule system with polyurethane acrylate (PUA) shell is prepared by interfacial polymerization between acrylic polyurethane diisocyanate and water to achieve controlled release via UV irradiation. The size of the microcapsule is influenced by the concentration of protecting colloid and property of acrylic polyurethane diisocyanate. When concentration of polyvinyl alcohol (PVA) is 5% and molar ratio of TDI and acrylic ethoxylated pentaerythritol (acrylic PP50) rises to 1.50, average diameter of the microcapsule is only 3.3223 μm. Delivery of 4‐hydroxy‐4′‐isopropoxydiphenylsulfone (D‐8) encapsuled by PUA microcapsule in solution can be prevented effectively by 30‐min UV irradiation. Lightness (L*) is used to measure color changes of reaction between D‐8 in PUA microcapsule and 2‐anilino‐6‐dibutylamino‐3‐methylfluoran (ODB‐2) under thermal treatment. In dry state, irradiated PUA microcapsules are much harder to release D‐8 than those not irradiated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,characterization, and UV‐curing properties of silicon‐containing (Meth)acrylate monomers

Eight different silicon‐containing (meth)acrylate monomers are synthesized by the substitution reaction of chlorosiloxanes with 2‐hydroxyethyl methacrylate or 2‐hydroxyethyl acrylate. Their molecular structures are confirmed by IR, ¹H‐NMR, and ¹³C‐NMR spectroscopic analyses. The effects of silicon content on the UV‐curing behavior, physical, surface, and thermal properties are investigated. The UV‐curing behavior is analyzed by photo differential scanning calorimetry. The surface free energy of the UV‐cured film is calculated from contact angles measured using the Lewis acid‐base three liquids method. The silicon‐containing (meth)acrylate monomers perform much better than traditional (meth)acrylate monomers on UV‐curing. The silicon‐containing monomers have higher final conversions and fast UV‐curing rates in photopolymerization. The surface free energy decreases with increasing silicon content, because silicon in the soft segment is transferred to the surface, producing a UV‐cured film; this is confirmed by X‐ray photoelectron spectroscopy measurements. All these advantageous properties enable these synthetic silicon‐containing monomers to perform better in applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis of novel polyurethanes containing dioxybenzylidenecyanoacetate,as non‐linear optical chromophores and their properties

Methyl 3,4‐di‐(2′‐hydroxyethoxy)benzylidenecyanoacetate (3) was prepared by hydrolysis of methyl 3,4‐di‐(2′‐vinyloxyethoxy)benzylidenecyanoacetate (2). Diol 3 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate, and 1,6‐hexamethylenediisocyanate to yield polyurethanes 4, 5 and 6 containing the non‐linear optical (NLO) chromophore 3,4‐dioxybenzylidenecyanoacetate. The resulting polyurethanes 4–6 were soluble in common organic solvents such as acetone and DMF. T_g values of the polymers obtained from DSC thermograms were in the range 80–102 °C. Polymers 4–6 showed thermal stability up to 300 °C in TGA thermograms, and electro‐optic coefficients (r₃₃) of the poled polymer films were in the range 10–12 pm V^?1 at 633 nm, which are acceptable for NLO device applications. © 2002 Society of Chemical Industry     

Synthesis and characterization of hyperbranched poly(silyl ester)s

Hyperbranched poly(silyl ester)s were synthesized via the A₂ + B₄ route by the polycondensation reaction. The solid poly(silyl ester) was obtained by the reaction of di‐tert‐butyl adipate and 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The oligomers with tert‐butyl terminal groups were obtained via the A₂ + B₂ route by the reaction of 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl‐trisi1oxane with excess amount of di‐tert‐butyl adipate. The viscous fluid and soft solid poly(silyl ester)s were obtained by the reaction of the oligomers as big monomers with 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The polymers were characterized by ¹H NMR, IR, and UV spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The ¹H NMR and IR analysis proved the existence of the branched structures in the polymers. The glass transition temperatures (T_g's) of the viscous fluid and soft solid polymers were below room temperature. The T_g of the solid poly(silyl ester) was not found below room temperature but a temperature for the transition in the liquid crystalline phase was found at 42°C. Thermal decomposition of the soft solid and solid poly(silyl ester)s started at about 130°C and for the others it started at about 200°C. The obtained hyperbranched polymers did not decompose completely at 700°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3430–3436, 2006     

Synthesis and properties of hydroxylated core-fluorinated diamines and polyurethanes based on them with azobenzene nonlinear optical chromophores in the backbone

We report on the synthesis of core-fluorinated phenylene- and biphenyldianilines, which was accomplished by diazotization reaction of diamines followed by coupling of the obtained diazonium salts with 2-[ethyl(phenyl)amino]-ethanol. Two types of core-fluorinated aromatic units were used in a molecular design of azo-chromophore monomers with enhanced second order nonlinear optical (NLO) properties: octafluorobiphenyl (OFB) and tetrafluorobenzene (TFB) ones. Polymerization of the monomers was performed to obtain polyurethanes with azo-chromophores in the main chain. Comparison of physical and optical properties of these polymers reveals that the main factor influencing the observed NLO activity of the latter is the inherent isomery of the macromolecular chains rather than a variation of the structure of electron-accepting groups.     

Nonenzymatic Oligomerization of 3′,5′‐Cyclic CMP Induced by Proton and UV Irradiation Hints at a Nonfastidious Origin of RNA

We report that 3′,5′‐cyclic CMP undergoes nonenzymatic di‐ and trimerization at 20 °C under dry conditions upon proton or UV irradiation. The reaction involves stacking of the cyclic monomers and subsequent polymerization through serial transphosphorylations between the stacked monomers. Proton‐ and UV‐induced oligomerization of 3′,5′‐cyclic CMP demonstrates that pyrimidines—similar to purines—might also have taken part in the spontaneous generation of RNA under plausible prebiotic conditions as well as in an extraterrestrial context. The observed polymerization of naturally occurring 3′,5′‐cyclic nucleotides supports the possibility that the extant genetic nucleic acids might have originated by way of a straight Occamian path, starting from simple reactions between plausibly preactivated monomers.     

Polyurethanes: Products of 4,4′‐bis(6‐hydroxyhexylthio)diphenyl ether and methylene bis(4‐phenyl isocyanate)

New linear polyurethanes derived from 4,4′‐bis(6‐hydroxyhexylthio)diphenyl ether and methylene bis(4‐phenyl isocyanate) were synthesized by either melt or solution polymerization with a strictly equimolar ratio of the monomers. In the solution method, good results were obtained with the aprotic solvent N,N‐dimethylformamide at an approximately 20 wt % concentration of the monomers, with dibutyltin dilaurate as a catalyst, the process being conducted at 90–100°C for 4 h. The basic physicochemical properties of the polymers were investigated with thermogravimetric analysis and differential scanning calorimetry. The molecular weight distribution was determined by gel permeation chromatography. Shore hardness and tensile test results were also examined. The structures of the resulting products were confirmed with elemental analysis, Fourier transform infrared, and X‐ray diffractometry. The properties of the copolyurethanes, containing various amounts of poly(oxytetramethylene) diol (～1000) or polycaprolactone diol (～1250) and synthesized under the conditions for the nonsegmented polyurethanes, were also examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 380–388, 2003     

支化与交联型聚氨酯弹性体的合成与性能分析

为提高聚氨酯弹性体力学性能和耐热性,本文以聚己二酸二乙二醇酯二醇、二苯基甲烷二异氰酸酯和 1,4-丁二醇为原料,以聚氧化丙烯三醇（PPG-3）或丙三醇为支化单体,并通过调控其添加量（1%、3%和5%,相对于PDGA-2000的摩尔分数）,采用本体预聚物法合成支化或交联型聚氨酯弹性体。与线型聚氨酯相比,支化聚氨酯具有较高机械强度和耐热性。添加3% PPG-3所制备支化聚氨酯的拉伸强度提高170%（33.9MPa）,撕裂强度提高36%（90.7MPa）,维卡软化点温度为95.1℃;然而,5%的丙三醇引发交联结构的形成,交联型聚氨酯的拉伸强度提高154%（31.8MPa）,撕裂强度提高26%（84.4MPa）,维卡软化点温度为150.6℃。此外,PPG-3和丙三醇发挥聚氨酯软段和硬段相容剂的作用,抑制微相分离,使聚氨酯弹性体的橡胶平台增大。动态流变行为测试结果表明,支化和交联型聚氨酯弹性体具有更高的弹性模量和复数黏度。     

Total replacement of solvent in polyurethane synthesis using carbon dioxide soluble 1,3‐dichlorodistannoxane catalysts

This work demonstrates catalytic synthesis of polyurethanes using 1,3‐dichlorodistannoxane catalysts ( 1 ) in carbon dioxide (CO₂) and carbon dioxide expanded liquids (CXL). Catalytic polyurethane synthesis was also performed in pure organic solvent (dimethylformamide) for comparison. In this study, mainly, 4, 4′‐methylene‐bis‐(phenyl isocyanate) (MDI) as the diisocyanate precursor and ethylene glycol (EG) as the diol precursor were used for polyurethane synthesis. In addition to MDI, hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), and p‐isocyanatobenzylisocyanate (PIBI) were also used for polyurethane synthesis with different diols or triol in CO₂. Polyurethanes with a molecular weight ranging from 3000 to 70,000 were synthesized depending upon the combination of diisocyanate and diol used. Comparable yields of polyurethanes were obtained using an all butyl group substituted ( 1a ) catalyst in CO₂ (55 bars, 50°C) and in DMF (50°C). Additionally, the yield and polydispersity index (PDI) of polymer formed in neat CO₂ was comparable with those synthesized in the largely used organic solvent DMF. Interestingly, catalyst 1a in CXL (55 bars, 50°C) gave higher yields, and polymers with lower PDI (1.19). Reactions carried out in scCO₂ at 145 bars using PIBI and EG were found to be about three times faster than the reaction carried out in DMF. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Photopolymerization and thermal behavior of phosphate diacrylate and triacrylate used as reactive‐type flame‐retardant monomers in ultraviolet‐curable resins

Tri(acryloyloxyethyl)phosphate (TAEP) and di(acryloyloxyethyl)ethyl phosphate (DAEEP) were used as reactive‐type flame‐retardant monomers along with commercial epoxy acrylate and polyurethane acrylate oligomers in ultraviolet (UV)‐curable resins. The concentrations of the monomers were varied from 17 to 50 wt %. The addition of the monomers greatly reduced the viscosity of the oligomers and increased the photopolymerization rates of the resins. The flame retardancy and thermal degradation behavior of the UV‐cured films were investigated with the limiting oxygen index (LOI) and thermogravimetric analysis. The results showed that the thermal stability at high temperatures greater than 400°C and the LOI values of the UV‐cured resins, especially those containing epoxy acrylate, were largely improved by the addition of the monomers. The dynamic mechanical thermal properties of the UV‐cured films were also measured. The results showed that the crosslink density increased along with the concentrations of the monomers. However, the glass‐transition temperature decreased with an increasing concentration of DAEEP because of the reduction in the rigidity of the cured films, whereas the glass‐transition temperature increased with the concentration of TAEP because of the higher crosslink density of the cured films. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 185–194, 2005     

Perfluoropolyether polymers by UV curing: design,synthesis and characterization

Perfluoropolyether (PFPE) structures can be functionalized with acrylic groups using appropriate hydrogenated acrylic monomers: the macromers obtained are highly reactive under UV irradiation, and fluorinated polymers can be obtained. In the first part of this work is described the synthesis of new PFPE (meth)acrylic oligomers by extending OH‐terminated fluorinated chains with urethane groups and reactive acrylic functions. The photopolymerization reaction of each product is then reported followed by the characterisation of the main thermal, mechanical and surface properties of UV‐cured coatings. The polymers have good thermal resistance and fair mechanical and chemical resistance. More interestingly they show very low refractive index and low surface tension. For these latter properties the products can be advantageously used in highly demanding applications such as photonic devices and nano‐patterning. Copyright © 2011 Society of Chemical Industry     

Biobased polyisocyanates from plant oil triglycerides: Synthesis,polymerization, and characterization

In this study, an easy and efficient synthesis of unsaturated plant oil triglycerides having isocyanate groups is reported. In the first step of the synthesis, the triglyceride was brominated at the allylic positions by a reaction with N‐bromosuccinimide, and in the second step, these brominated species were reacted with AgNCO to convert them to isocyanate‐containing triglycerides. At the end of the reaction, approximately 60–70% of the bromine was replaced by NCO groups, and the double bonds of the triglyceride were not consumed. When the amount of AgNCO was increased, the yield also increased. The final products were characterized with IR and ¹H‐NMR, and polyurethanes and polyureas were obtained from these fatty isocyanates with alcohols and amines, respectively. The polymers were characterized by differential scanning calorimetry and thermogravimetric analysis. Differential scanning calorimetry curves showed that glycerin polyurethane showed a glass‐transition temperature at 19°C, castor oil polyurethane showed two glass‐transition temperatures at ?43 and 36°C, and triethylene tetraamine polyurea showed a glass‐transition temperature at 31°C. Some properties of the polymers, such as the tensile strength and swelling ratios, were also determined. The swelling rate of glycerin polyurethane was higher than that of castor oil polyurethane in dichloromethane. The equilibrium swelling ratio was highest for the castor oil polyurethane. The polyurethanes synthesized in this study had a Young's modulus around 50 kPa and a tensile strength around 0.01 N/mm² (100 kPa). The tensile strength of glycerin polyurethane was higher than that of castor oil polyurethane. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008