Synthesis and thermomechanical characterization of polyurethane elastomers extended with α,ω‐alkane diols

A series of polyurethane (PU) elastomers was prepared by the reaction of poly(?‐caprolactone) and 4,4′‐diphenylmethane diisocyanate, which was extended with a series of chain extenders (CEs) having 2–10 methylene units in their structure. The completion of the reaction was confirmed by Fourier transform infrared spectroscopy. The chemical structures of the synthesized PU samples were characterized with Fourier transform infrared, ¹H‐NMR, and ¹³C‐NMR spectroscopy, and the thermal properties were determined by thermogravimetric analysis, DSC, and dynamic mechanical thermal analysis techniques. The mechanical properties were also studied and are discussed. The thermogravimetric analysis and DSC analysis showed that CE length had a considerable effect on the thermal properties of the prepared samples. The dynamic mechanical thermal analysis and damping peaks were also affected by the number of methylene units in the CE length. The elastomer extended with 1,2‐ethane diol exhibited optimum thermal properties, whereas the elastomer based on 1,10‐decane diol displayed the worst thermal properties. Tensile strength and elongation at break decreased with increasing CE length, whereas hardness showed the opposite trend. The glass‐transition temperature moved toward lower temperatures with increasing CE length. The decrease in the glass‐transition temperature and tensile properties were interpreted in terms of decreasing hard segments and increasing chain flexibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of α‐butyl‐ω‐N,N‐dihydroxyethylaminopropylpolydimethylsiloxane

α‐Butyl‐ω‐N,N‐dihydroxyethylaminopropylpolydimethylsiloxane, a monotelechelic polydimethylsiloxane with a diol‐end group, which is used to prepare polyurethane–polysiloxane graft polymer, was successfully synthesized. The preparation included five steps, which are hydroxyl protection, alkylation, anionic ring‐opening polymerization, hydrosilylation, and deprotection. The products were characterized by FTIR, GC, LC‐MS, ¹H NMR, and elemental analysis. The results showed that each step was successfully carried out and the targeted products were synthesized in all cases. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of α‐butyl‐omega‐{3‐[2‐hydroxy‐3‐(N‐methyl‐N‐hydroxy‐ ethylamino)propoxy]propyl}polydimethylsiloxane

A novel synthesis path for the monotelechelic polydimethylsiloxane with a diol‐end group, α‐butyl‐omega‐{3‐[2‐hydroxy‐3‐(N‐methyl‐N‐hydroxyethylamino)propoxy]propyl}polydimethylsiloxane, is described in this article. The preparation included three steps, which were anionic ring‐opening polymerization, hydrosilylation, and epoxy addition. The structure and polydispersity index of the products were analyzed and confirmed by FTIR, ¹H NMR, ¹³C NMR, H? H, and C? H. Correlated Spectroscopy and gel permeation chromatography. The results demonstrated that each step was successfully carried out and the targeted products were accessed in all cases. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation,morphology, and mechanical properties of elastomers based on α,ω‐dihydroxy‐polydimethylsiloxane/polystyrene blends

α,ω‐Dihydroxy‐polydimethylsiloxane/polystyrene (PDMS/PS) blends were prepared by the solution polymerization of styrene (St) in the presence of α,ω ‐dihydroxy‐polydimethylsiloxane (PDMS), using toluene as solvent and benzoyl peroxide (BPO) as initiator. The PDMS/PS blends obtained by this method are a series of stable, white gums, which were vulcanized to elastomers at room temperature with methyl‐triethoxysilicane (MTES). The use level of MTES was far more than the necessary amount used to end‐link hydroxy‐terminated chains of PDMS, with the excess being hydrolyzed to crosslinked networks, which were similar to SiO₂ and acted as filler. Investigations were carried out on the elastomeric materials by extraction measurement, swelling measurement, and scanning electron microscopy. The extraction data show that at each composition the amount of soluble fraction is less than expected and the difference between experimental and theoretical values becomes more and more significant as PS content increases. This is mainly due to the grafting of PS onto PDMS and the entanglement of PS in the interpenetrating polymer network (IPN), which consists of either directly linked PDMS chains or chains linked via PS grafts and is formed by free radical crosslinking of PDMS during the radical polymerization of St. PS grafted on PDMS is insoluble and PS entangled in the IPN is difficult to extract. Both render the soluble fraction to be less than expected. As the St content in preparing PDMS/PS blends increases, the probability of grafting PS onto PDMS also increases, which may subsequently produce a higher crosslinking level of PDMS networks that linked via PS grafts by radical crosslinking. As a result, not only the amount of insoluble PS increases but also PS entangled in the IPN is more difficult to extract. Scanning electron microscopy demonstrates that the elastomer system has a microphase‐separated structure and a certain amount of PS remains in the PDMS networks after extraction, which is in accordance with the extraction data. Moreover, the mechanical properties of the elastormeric materials have been studied in detail. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3542–3548, 2004     

Cationic copolymers of α,β‐poly‐(N‐2‐hydroxyethyl)‐DL‐aspartamide (PHEA) and α,β‐polyasparthylhydrazide (PAHy): synthesis and characterization

In the present study the derivatization of two water‐soluble synthetic polymers, α,β‐poly(N‐2‐hydroxyethyl)‐DL ‐aspartamide (PHEA) and α,β‐polyasparthylhydrazide (PAHy), with glycidyltrimethylammonium chloride (GTA) is described. This reaction permits the introduction of positive charges in the macromolecular chains of PHEA and PAHy in order to make easier the electrostatic interaction with DNA. Different parameters affect the reaction of derivatization, such as GTA concentration and reaction time. PHEA reacts partially and slowly with GTA; on the contrary the reaction of PAHy with GTA is more rapid and extensive. The derivatization of PHEA and PAHy with GTA is a convenient method to introduce positive groups in their chains and it permits the preparation of interpolyelectrolyte complexes with DNA. © 2000 Society of Chemical Industry     

The preparation of α‐bis and α,ω‐tetrakis aromatic oxazolyl‐ and carboxyl‐functionalized polymers using 1,1‐bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethylene in atom transfer radical polymerization reactions

The preparation of new compounds, 1,1‐bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethanol and a new symmetrically disubstituted 1,1‐diphenylethylene derivative, 1,1‐bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethylene, is described. 1,1‐Bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethylene was utilized as a dioxazolyl initiator precursor for the polymerization of styrene by atom transfer radical polymerization (ATRP) methods to produce α‐bis(oxazolyl) polystyrene. The kinetic study of the polymerization process indicated that the free radical polymerization reaction for the preparation of α‐bis(oxazolyl) polystyrene follows first‐order rate kinetics with respect to monomer consumption. α,ω‐Tetrakis(oxazolyl) polystyrene was prepared by a new, in situ, controlled/living, post‐ATRP chain‐end‐functionalization reaction which involves the direct addition of 1,1‐bis[4‐(2‐(4,4‐dimethyl‐1,3‐oxazolyl))phenyl]ethylene to the ω‐terminus of the α‐bis(oxazolyl) polystyrene derivative, without the isolation and purification of the polymeric precursor. α‐Bis(carboxyl) and α,ω‐tetrakis(carboxyl) polystyrene derivatives were obtained by the quantitative chemical transformation of the oxazoline groups of the respective aromatic oxazolyl chain‐end‐functionalized polystyrene derivatives to the aromatic carboxyl groups. The organic precursor compounds, the dioxazolyl‐functionalized 1,1‐diphenylethylene derivative and the functionalized polymers were characterized using ¹H NMR and ¹³C NMR spectrometry and Fourier transform infrared spectroscopy, size‐exclusion and thin‐layer chromatography and non‐aqueous titration measurements. © 2014 Society of Chemical Industry     

Microbial Synthesis of Medium‐Chain α,ω‐Dicarboxylic Acids and ω‐Aminocarboxylic Acids from Renewable Long‐Chain Fatty Acids

Biotransformation of long‐chain fatty acids into medium‐chain α,ω‐dicarboxylic acids or ω‐aminocarboxylic acids could be achieved with biocatalysts. This study presents the production of α,ω‐dicarboxylic acids (e.g., C₉, C₁₁, C₁₂, C₁₃) and ω‐aminocarboxylic acids (e.g., C₁₁, C₁₂, C₁₃) directly from fatty acids (e.g., oleic acid, ricinoleic acid, lesquerolic acid) using recombinant Escherichia coli‐based biocatalysts. ω‐Hydroxycarboxylic acids, which were produced from oxidative cleavage of fatty acids via enzymatic reactions involving a fatty acid double bond hydratase, an alcohol dehydrogenase, a Baeyer–Villiger monooxygenase and an esterase, were then oxidized to α,ω‐dicarboxylic acids by alcohol dehydrogenase (ADH, AlkJ) from Pseudomonas putida GPo1 or converted into ω‐aminocarboxylic acids by a serial combination of ADH from P. putida GPo1 and an ω‐transaminase of Silicibacter pomeroyi. The double bonds present in the fatty acids such as ricinoleic acid and lesquerolic acid were reduced by E. coli‐native enzymes during the biotransformations. This study demonstrates that the industrially relevant building blocks (C₉ to C₁₃ saturated α,ω‐dicarboxylic acids and ω‐aminocarboxylic acids) can be produced from renewable fatty acids using biocatalysis.

     

Protein adsorption materials based on conducting polymers: polypyrrole modified with ω‐(N‐pyrrolyl)‐octylthiol

In order to fabricate a new polymer matrix for application in biochips and to understand the mechanism of adsorption of proteins on conducting polymers, we prepared polypyrrole (PPy) functionalized with ω‐(N‐pyrrolyl)‐octylthiol moieties. The chemical structure of the polymer could be controlled by varying the concentration of pyrrole added as the monomer. Initially, ω‐(N‐pyrrolyl)‐octylthiol was self‐assembled into a monolayer on a gold surface. Thereafter, a layer of uniform and smooth PPy was obtained by the chemical copolymerization of pyrrole and the ω‐(N‐pyrrolyl)‐octylthiol. Bovine serum albumin (BSA) adsorption on the polymer was investigated using surface plasmon resonance spectroscopy and cyclic voltammograms. The chemical structure and monomer components of the as‐prepared films were characterized using Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. Water contact angle measurements were used to assess the surface wettability of the films throughout the preparative procedure. The kinetics of BSA adsorption onto the polymer could be controlled by varying the copolymer thickness and the pH value of the buffer solutions used. Moreover, the electroactivity was changed upon BSA binding. The results suggest that the new conducting polymer may potentially be applied as a more sensitive and reliable matrix in protein sensors. Copyright © 2011 Society of Chemical Industry     

Synthesis of α,ω‐isocyanate telechelic polymethacrylate soft segments with activated ester side functionalities and their use for polyurethane synthesis

The synthetic route for the preparation of α,ω‐isocyanate‐telechelic poly(methyl methacrylate‐co‐acryloxysuccinimide) and α,ω‐ isocyanate‐telechelic poly(methyl methacrylate‐co‐acrylamidohexanoic succinimide) soft segments is presented. The strategy includes reversible addition fragmentation chain transfer (RAFT) copolymerization and two post polymerization modification steps. The RAFT polymerizations result in copolymers with an activated ester proportion within the polymer chains of 8% N‐acryloxysuccinimide and 5% 6‐acrylamidohexanoic succinimide. The reactivity ratios of the monomer pairs were determined. In a first post polymerization reaction carboxylic acid homo telechelic polymers were prepared by reacting the ω‐dithiobenzoate end‐group with an excess of azobis(cyanovaleric acid). In a second modification step the α‐ and ω‐carboxylic acid end‐groups were reacted with hexamethylene diisocyanate and 100% isocyanate telechelic copolymers were obtained. Finally segmented polyurethanes were prepared by coupling hexamethylene diisocyanate (HDI) end capped soft segments with hard segments composed of 1,4‐butanediol and HDI. © 2013 Society of Chemical Industry     

Synthesis and characterization of photoluminescent conjugated polymer containing N‐(α‐naphthyl)‐carbazole unit

A novel luminescent conjugated polymer, poly[{9‐(α‐naphthyl)‐3,6‐divinylenecarbazolylene}‐alt‐co‐(1,4‐phenylene)] (PNVCP), bearing alternated 9‐(α‐naphthyl)‐carbazole and benzene units, was synthesized via a Wittig–Horner reaction. The solubility, thermal, and optical properties were investigated. It was soluble in common organic solvents, such as tetrahydrofuran and 1,2‐dichlororoethane. Thermogravimetric analysis and differential scanning calorimetry showed that the conjugated polymer exhibited good thermal stability up to 496°C with a glass‐transition temperature higher than 110°C. The photoluminescence properties were studied. The polymer emits blue light and the quantum yield is 93% in solution. The emission spectra exhibited an obvious solvent effect. With the increase of the polarity of the solvents, the fluorescence spectra changed obviously and appeared to be redshifted at room temperature. The redshift was more obvious in aromatic solvents than in aliphatic solvents. When N,N‐dimethylaniline was gradually added into the solution of the conjugated polymer, the emission intensity of the fluorescence decreased. In comparison, the emission intensity of the polymer showed invariability when 1,4‐dicyanobenzene was added into the polymer solution. Moreover, the fluorescence of the polymer could be effectively quenched by fullerene. Overall, the synthesized polymer is a potential candidate material for fabrication of polymeric light‐emitting devices. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 923–927, 2006     

Preparation,morphology, and mechanical properties of elastomers based on α,ω‐dihydroxy‐polydimethylsiloxane/poly(methyl methacrylate) blends

α,ω‐Dihydroxy‐polydimethylsiloxane (PDMS)/poly(methyl methacrylate) (PMMA) blends were prepared by the radical polymerization of methyl methacrylate in the presence of PDMS, with benzoyl peroxide as the initiator. The PDMS/PMMA blends obtained by this method were a series of stable, white gums, which were vulcanized into elastomers at room temperature with methyl triethoxysilicane (MTES). The MTES dosage was much larger than the amount necessary for end‐linking the hydroxy‐terminated chains of PDMS, with the excess being hydrolyzed into crosslinked networks, which were similar to SiO₂ and acted as fillers. Investigations were carried out on the elastomeric materials by extraction measurements, swelling measurements, and scanning electron microscopy. The extraction data showed that at each composition, the sol fraction was less than expected. The extracted materials were further studied with swelling measurements, which revealed that the material obtained from an elastomer with a higher PMMA content had an apparently larger equilibrium swelling degree. Scanning electron microscopy demonstrated that the elastomer system had a microphase‐separated structure consisting of PMMA domains within a continuous PDMS matrix. Moreover, the mechanical properties of the elastomeric materials were studied in detail. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1547–1553, 2006     

Prostaglandins and prostaglandin intermediates. XIV. Synthesis of rac-9α, 11α, 13α-trihydroxy- and rac-9α, 11α, 13β-Trihydroxy-5(Z)-prosten-15-ynoic Acid

Attempts to rearrange a β-hydroxy-alkyne with a secondary hydroxy group into an α,β-unsaturated ketone failed in the case of a potential prostaglandin intermediate. However, it was possible to convert this intermediate into 13-hydroxy-5(Z)-prosten-15-ynoic acids, which are interesting prostaglandin analogues with a modified alkyl side chain.     

Poly(α,α,α′,α′-tetrafluoro-p-xylylene)

Poly(α,α,α′,α′-tetrafluoro-p-xylylene) was prepared by the pyrolysis of cyclo-di-(α,α,α′,α′-tetrafluoro-p-xylylene) and by the pyrolysis of α,α′-bis(alkylsulfonyl)-α,α,α′,α′-tetrafluoro-p-xylene. The pyrolysis of α,α′-dibromo-α,α,α′,α′-tetrafluoro-p-xylylene also gave the polymer, but the method is less satisfactory. Poly(α,α,α′,α′-tetrafluoro-p-xylylene) shows remarkable thermal and oxidative stability at elevated temperatures. Useful mechanical and electrical properties are retained after aging for 3000 hr at 250° in air. After initial change due to crystallization, tensile strength remains near 10,000 psi, elongation above 5%, and dielectric constants and dissipation factors at approximately 2.4 and .001, respectively.     

Polyaniline doped with α, ω‐alkanedisulfonic acids: preparation and characterization

The use of α, ω‐alkanedisulfonic acid, HO₃S(CH₂)_nSO₃H (n = 1, 4, 6 and 12), as a dopant for polyaniline (PANi) was investigated. This series of disulfonic acids with varying chain lengths were synthesized and used in the doping of PANi. The doped polymers showed conductivity in the range 10^?2 to 10^?1 S cm^?1. Thermal studies showed that the doped polymers, depending on the chain length of α,ω‐alkanedisulfonic acid, were stable up to ca 300 °C and the thermal stability decreased with increasing dopant chain length. The thermal stability of α,ω‐alkanedisulfonic acid‐doped PANi was higher than that of alkanesulfonic acid‐doped PANi which typically degrades around 250 °C, suggesting a moderately broader processing window for α,ω‐alkanedisulfonic acid‐doped PANi for blending with other thermoplastics. Copyright © 2012 Society of Chemical Industry     

Synthesis of α, α′, β-trideuterovinyl acetate

Reaction conditions for the synthesis of α, α′, β-trideuterovinyl acetate by the continuous vapour phase catalytic reaction of deuteroacetylene and acetic acid-d (CH₃COOD) are described.     

Combined Biocatalytic and Chemical Transformations of Oleic Acid to ω‐Hydroxynonanoic Acid and α,ω‐Nonanedioic Acid

A practical chemoenzymatic method for the synthesis of 9‐hydroxynonanoic acid and 1,9‐nonanedioic acid (i.e., azelaic acid) from oleic acid [(9Z)‐octadec‐9‐enoic acid] was investigated. Biotransformation of oleic acid into 9‐(nonanoyloxy)nonanoic acid via 10‐hydroxyoctadecanoic acid and 10‐keto‐octadecanoic acid was driven by a C‐9 double bond hydratase from Stenotrophomonas maltophilia, an alcohol dehydrogenase from Micrococcus luteus, and a Baeyer–Villiger monooxygenase (BVMO) from Pseudomonas putida KT2440, which was expressed in recombinant Escherichia coli. After production of the ester (i.e., the BVMO reaction product), the compound was chemically hydrolyzed to n‐nonanoic acid and 9‐hydroxynonanoic acid because n‐nonanoic acid is toxic to E. coli. The ester was also converted into 9‐hydroxynonanoic acid and the n‐nonanoic acid methyl ester, which can be oxygenated into the 9‐hydroxynonanoic acid methyl ester by the AlkBGT from P. putida GPo1. Finally, 9‐hydroxynonanoic acid was chemically oxidized to azelaic acid with a high yield under fairly mild reaction conditions. For example, whole‐cell biotransformation at a high cell density (i.e., 10 g dry cells/L) allowed the final ester product concentration and volumetric productivity to reach 25 mM and 2.8 mM h⁻¹, respectively. The overall molar yield of azelaic acid from oleic acid was 58%, based on the biotransformation and chemical transformation conversion yields of 84% and 68%, respectively.

     

Poly‐α,β‐(3‐hydroxypropyl)‐DL‐aspartamide: A new drug carrier

Poly‐α,β‐(3‐hydroxypropyl)‐DL ‐aspartamide (PHPA) was synthesized by the ring‐open reaction of polysuccinimide (PSI) and 3‐hydroxypropylamine. The polymer was characterized by ¹H‐NMR, ¹³C‐NMR, FTIR, and GPC. Mark–Houwink coefficients were obtained from viscometry and GPC measurements, K = 5.53 × 10⁻³ and α = 0.78 in water. The acute toxicity of PHPA was examined and it revealed no death in ICR mice up to the dose treated of 15.3 kg/kg, and hematological parameters showed no significant difference between treated and control animals. The potential use of PHPA as a drug carrier was also investigated. In a typical case, a contraceptive drug, norethindrone (NET), was bonded to PHPA, and the drug sustained released as long as 120 days an in vitro test. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2411–2417, 2000     

Synthesis of Oligoester α,ω‐diols by Alcoholysis of PET through the Reactive Extrusion Process

The alcoholysis of PET with diols in the presence of dibutyltinoxide was carried out in a twin‐screw extruder with residence times of 1 min and without solvent. The reaction led to scissions of PET chains and to the synthesis of oligoester α,ω‐diols with average number molecular weights of about 1000 g·mol^—1 characterised by conventional techniques such as NMR, SEC and MALDI‐TOF. The alcoholysis kinetics was studied with a rheological tool under selected conditions, and it was shown that this reaction is quite compatible with the residence times in an extruder. This study clearly shows that the oligoesters synthesised by reactive extrusion have characteristics similar to the oligoesters synthesised by batch processes over many hours. Furthermore, the melting temperature of these oligoesters can be controlled between room temperature and 220°C by using diols with different structures for the alcoholysis.