This article presents a comparative study of ibuprofen materials in their solid state. Ibuprofen ... more This article presents a comparative study of ibuprofen materials in their solid state. Ibuprofen crystallizes into two different structures for the S(+) enantiomer (dexibuprofen) and racemic ibuprofen. The crystal structure of ibuprofen, its optical absorption and photoluminescence, and the thermodynamic results (melting point and heat of fusion) are discussed. From these physicochemical properties, the authors conclude that dexibuprofen, which is the most active species pharmaceutically, and racemic ibuprofen are inherently different solid‐state materials.
Chemical and Biochemical Engineering Quarterly, Jul 12, 2015
This review summarizes the state-of-the-art knowledge of the usage of poly(hydroxy alkanoate)s in... more This review summarizes the state-of-the-art knowledge of the usage of poly(hydroxy alkanoate)s in medical and sanitary applications. Depending on the monomers incorporated into the polymers and copolymers, this class of polymers exhibits a broad range of (thermo-)plastic properties, enabling their processing by, e.g., solution casting or melt extrusion. In this review, strategies for the polymer analogous modification of these materials and their surfaces are highlighted and correlated with the potential applications of the corresponding materials and blends. While the commercial availability of purified PHAs is addressed in brief, special focus is put on the (bio-)degradability of these polymers and ways to influence the degradation mechanism and/or the duration of degradation.
International Journal of Pharmaceutics, Sep 1, 2016
The objective of this study was to analyze differences in the subtle microstructure of three diff... more The objective of this study was to analyze differences in the subtle microstructure of three different grades of HMPC hard capsule shells using mechanical, spectroscopic, microscopic and tomographic approaches. Dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), vibrational spectroscopic, X-Ray scattering techniques as well as environmental scanning electron microscopy (ESEM) and optical coherence tomography (OCT) were used. Two HPMC capsules manufactured via chemical gelling, one capsule shell manufactured via thermal gelling and one thermally gelled transparent capsule were included. Characteristic micro-structural alterations (associated manufacturing processes) such as mechanical and physical properties relevant to capsule performance and processability were thoroughly elucidated with the integration of data obtained from multimethodological investigations. The physico-chemical and physico-mechanical data obtained from a gamut of techniques implied that thermally gelled HPMC hard capsule shells could offer an advantage in terms of machinability during capsule filling, owing to their superior micro-and macroscopic structure as well as specifically the mechanical stability under dry or humid conditions. 2016 Elsevier B.V. All rights reserved.
Homopolymers of 2-norbornene and 2,3-bis(trifluoromethyl)-2,5-norbornadiene and copolymers of the... more Homopolymers of 2-norbornene and 2,3-bis(trifluoromethyl)-2,5-norbornadiene and copolymers of these bicyclic olefins with 1,5-cyclooctadiene and cyclopentene were prepared via ring opening metathesis polymerization. The molecular weight distributions of the polymers were estimated by gel permeation chromatography. The polymers were degraded in a cross metathesis reaction with E-4-octene; only poly[2,3-bis(trifluoromethyl),2,5-norbornadiene] was not degradable. All reactions were carried out with WC16/(CH3)4Sn as the catalyst system. The low molecular cyclic oligomers in the polymerization mixtures and the degradation products were analyzed by gas chromatography and identified using a gas chromatography/mass spectrometry coupling. The degradation experiments show reactivity differences for the double bonds situated in the polymer backbone. On the basis of these differences and the fact that this is the first time that a metathesis degradation of such polymers has been reported, the consequences on the ring opening metathesis copotymerization of cycloolefins are discussed in general terms, leading to some new aspects in the planning of the synthesis of special copolymers and oligomers.
(-)-endo-2-Acetoxy-bicycle [ 2.2.11 hept-S-ene ((-)-endo-2-norbomenyl acetate) was synthesized fr... more (-)-endo-2-Acetoxy-bicycle [ 2.2.11 hept-S-ene ((-)-endo-2-norbomenyl acetate) was synthesized from (-)-endo-2-norbomenyl butyrate which was separated from the racemic mixture by enzymatic hydrolysis using Candida cylindracea lipase to provide monomers with high enantiomeric purity (ee> 95%). The monomer was polymerized via ring opening metathesis polymerization (ROMP) using Mo(CH-t-Bu) (NAr) (0-t-Bu) 2 and other similar molybdenum-carbene catalysts in different solvents. All reactions yielded optically active polymers with the specific rotation [a] ,, depending on catalyst and solvent. Spectroscopic data (IR, NMR) of the polymers show the influences of catalysts and solvents on the stereochemistry of the polymerization reaction.
The development of photoresists with decreased feature sizes and their application in photolithog... more The development of photoresists with decreased feature sizes and their application in photolithog. has become an active field of research. Neg. photoresists reproduce the geometric patterns of illumination masks by the crosslinking of polymers, yielding insol. 2.5-dimensional surface structures. Advancing our work on water-developable poly(2-oxazoline)-based neg. photoresists, we here present poly(2-oxazoline)-based photoresists from renewable resources. The 2-oxazoline monomers used in the synthesis of the photoresist were synthesized in a one-pot solvent-free reaction of ethanol amine with fatty acids from natural resources, namely undecenoic acid (castor oil) and decanoic acid (coconut oil). The microwave-assisted polymns. were performed at a scale of 300 g in an ionic liq., maximizing the efficiency of energy input, solvent recyclability and polymer recovery, chiefly due the pptn. of the copolymers from the ionic liq. upon cooling. The copolymer was characterized by structural a...
Bifunctional esters containing terminal bromo aryl and vinyl groups were polymerized with Pd(0) c... more Bifunctional esters containing terminal bromo aryl and vinyl groups were polymerized with Pd(0) catalyst to soluble precursor polymers, which could be easily converted to poly(p-phenylene-1,3-butadiene-1,4-ylene). The transformation into the conjugated polymer was investigated with DSC, TGA, FT-IR, UV/vis, PL and DIMS. Resulting polymer shows a bathochromic shift of absorbance and photoluminescence spectra in comparison to PPP and PPV. The experimentally determined value for the bandgap energy Es is 2.25 eV, which was predicted due to theoretical calculations (Es = 2.06 eV).
ABSTRACT We report an optical study of Side Chain Polymer Liquid Crystals (SCPLCs) in magnetic fi... more ABSTRACT We report an optical study of Side Chain Polymer Liquid Crystals (SCPLCs) in magnetic fields up to 20T. A novel sensitive set-up, which allows simultaneous birefringence and static light scattering measurements, was used to study polynorborene and polyacrylate based SCPLCs. We find that only magnetic fields bigger than a threshold value B min are able to induce orientation effects and this only at the crossing of the Isotropic-Nematic (IN) transition when cooling from the melt. The existence of a minimum field B min proves to be general, while its value is strongly dependent on the polymeric backbone elasticity, polymerization degree and spacer length. We have produced bulk and thin film aligned samples, stable at room temperature, characterized by an optical uniaxial anisotropy, with a director order parameter S D ∼0.9999.
Recently, we have reported the synthesis and ring-opening metathesis polymerization of enantiomer... more Recently, we have reported the synthesis and ring-opening metathesis polymerization of enantiomerically pure and racemic methyl-N-(1-phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate. In this paper, we present a new optically active 2-azanorbornene derivative that undergoes ring-opening metathesis polymerization in the presence of molybdenum alkylidene initiators of the type Mo(CH-t-Bu) (NAr)(OR2). Enantiomerically pure (1-phenylethyl)-N-(1-phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene-3-carboxamide 1 can be obtained through an asymmetric Lewis-acid-catalyzed Diels–Alder reaction of cyclopentadiene with
Biobased and biodegradable polymers (BBDs) such as poly(3-hydroxy-butyrate), PHB, and poly(3-hydr... more Biobased and biodegradable polymers (BBDs) such as poly(3-hydroxy-butyrate), PHB, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are considered attractive alternatives to fossil-based plastic materials since they are more environmentally friendly. One major problem with these compounds is their high crystallinity and brittleness. In order to generate softer materials without using fossil-based plasticizers, the suitability of natural rubber (NR) as an impact modifier was investigated in PHBV blends. Mixtures with varying proportions of NR and PHBV were generated, and samples were prepared by mechanical mixing (roll mixer and/or internal mixer) and cured by radical C–C crosslinking. The obtained specimens were investigated with respect to their chemical and physical characteristics, applying a variety of different methods such as size exclusion chromatography, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal analysis, XRD, and mecha...
This article presents a comparative study of ibuprofen materials in their solid state. Ibuprofen ... more This article presents a comparative study of ibuprofen materials in their solid state. Ibuprofen crystallizes into two different structures for the S(+) enantiomer (dexibuprofen) and racemic ibuprofen. The crystal structure of ibuprofen, its optical absorption and photoluminescence, and the thermodynamic results (melting point and heat of fusion) are discussed. From these physicochemical properties, the authors conclude that dexibuprofen, which is the most active species pharmaceutically, and racemic ibuprofen are inherently different solid‐state materials.
Chemical and Biochemical Engineering Quarterly, Jul 12, 2015
This review summarizes the state-of-the-art knowledge of the usage of poly(hydroxy alkanoate)s in... more This review summarizes the state-of-the-art knowledge of the usage of poly(hydroxy alkanoate)s in medical and sanitary applications. Depending on the monomers incorporated into the polymers and copolymers, this class of polymers exhibits a broad range of (thermo-)plastic properties, enabling their processing by, e.g., solution casting or melt extrusion. In this review, strategies for the polymer analogous modification of these materials and their surfaces are highlighted and correlated with the potential applications of the corresponding materials and blends. While the commercial availability of purified PHAs is addressed in brief, special focus is put on the (bio-)degradability of these polymers and ways to influence the degradation mechanism and/or the duration of degradation.
International Journal of Pharmaceutics, Sep 1, 2016
The objective of this study was to analyze differences in the subtle microstructure of three diff... more The objective of this study was to analyze differences in the subtle microstructure of three different grades of HMPC hard capsule shells using mechanical, spectroscopic, microscopic and tomographic approaches. Dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), vibrational spectroscopic, X-Ray scattering techniques as well as environmental scanning electron microscopy (ESEM) and optical coherence tomography (OCT) were used. Two HPMC capsules manufactured via chemical gelling, one capsule shell manufactured via thermal gelling and one thermally gelled transparent capsule were included. Characteristic micro-structural alterations (associated manufacturing processes) such as mechanical and physical properties relevant to capsule performance and processability were thoroughly elucidated with the integration of data obtained from multimethodological investigations. The physico-chemical and physico-mechanical data obtained from a gamut of techniques implied that thermally gelled HPMC hard capsule shells could offer an advantage in terms of machinability during capsule filling, owing to their superior micro-and macroscopic structure as well as specifically the mechanical stability under dry or humid conditions. 2016 Elsevier B.V. All rights reserved.
Homopolymers of 2-norbornene and 2,3-bis(trifluoromethyl)-2,5-norbornadiene and copolymers of the... more Homopolymers of 2-norbornene and 2,3-bis(trifluoromethyl)-2,5-norbornadiene and copolymers of these bicyclic olefins with 1,5-cyclooctadiene and cyclopentene were prepared via ring opening metathesis polymerization. The molecular weight distributions of the polymers were estimated by gel permeation chromatography. The polymers were degraded in a cross metathesis reaction with E-4-octene; only poly[2,3-bis(trifluoromethyl),2,5-norbornadiene] was not degradable. All reactions were carried out with WC16/(CH3)4Sn as the catalyst system. The low molecular cyclic oligomers in the polymerization mixtures and the degradation products were analyzed by gas chromatography and identified using a gas chromatography/mass spectrometry coupling. The degradation experiments show reactivity differences for the double bonds situated in the polymer backbone. On the basis of these differences and the fact that this is the first time that a metathesis degradation of such polymers has been reported, the consequences on the ring opening metathesis copotymerization of cycloolefins are discussed in general terms, leading to some new aspects in the planning of the synthesis of special copolymers and oligomers.
(-)-endo-2-Acetoxy-bicycle [ 2.2.11 hept-S-ene ((-)-endo-2-norbomenyl acetate) was synthesized fr... more (-)-endo-2-Acetoxy-bicycle [ 2.2.11 hept-S-ene ((-)-endo-2-norbomenyl acetate) was synthesized from (-)-endo-2-norbomenyl butyrate which was separated from the racemic mixture by enzymatic hydrolysis using Candida cylindracea lipase to provide monomers with high enantiomeric purity (ee> 95%). The monomer was polymerized via ring opening metathesis polymerization (ROMP) using Mo(CH-t-Bu) (NAr) (0-t-Bu) 2 and other similar molybdenum-carbene catalysts in different solvents. All reactions yielded optically active polymers with the specific rotation [a] ,, depending on catalyst and solvent. Spectroscopic data (IR, NMR) of the polymers show the influences of catalysts and solvents on the stereochemistry of the polymerization reaction.
The development of photoresists with decreased feature sizes and their application in photolithog... more The development of photoresists with decreased feature sizes and their application in photolithog. has become an active field of research. Neg. photoresists reproduce the geometric patterns of illumination masks by the crosslinking of polymers, yielding insol. 2.5-dimensional surface structures. Advancing our work on water-developable poly(2-oxazoline)-based neg. photoresists, we here present poly(2-oxazoline)-based photoresists from renewable resources. The 2-oxazoline monomers used in the synthesis of the photoresist were synthesized in a one-pot solvent-free reaction of ethanol amine with fatty acids from natural resources, namely undecenoic acid (castor oil) and decanoic acid (coconut oil). The microwave-assisted polymns. were performed at a scale of 300 g in an ionic liq., maximizing the efficiency of energy input, solvent recyclability and polymer recovery, chiefly due the pptn. of the copolymers from the ionic liq. upon cooling. The copolymer was characterized by structural a...
Bifunctional esters containing terminal bromo aryl and vinyl groups were polymerized with Pd(0) c... more Bifunctional esters containing terminal bromo aryl and vinyl groups were polymerized with Pd(0) catalyst to soluble precursor polymers, which could be easily converted to poly(p-phenylene-1,3-butadiene-1,4-ylene). The transformation into the conjugated polymer was investigated with DSC, TGA, FT-IR, UV/vis, PL and DIMS. Resulting polymer shows a bathochromic shift of absorbance and photoluminescence spectra in comparison to PPP and PPV. The experimentally determined value for the bandgap energy Es is 2.25 eV, which was predicted due to theoretical calculations (Es = 2.06 eV).
ABSTRACT We report an optical study of Side Chain Polymer Liquid Crystals (SCPLCs) in magnetic fi... more ABSTRACT We report an optical study of Side Chain Polymer Liquid Crystals (SCPLCs) in magnetic fields up to 20T. A novel sensitive set-up, which allows simultaneous birefringence and static light scattering measurements, was used to study polynorborene and polyacrylate based SCPLCs. We find that only magnetic fields bigger than a threshold value B min are able to induce orientation effects and this only at the crossing of the Isotropic-Nematic (IN) transition when cooling from the melt. The existence of a minimum field B min proves to be general, while its value is strongly dependent on the polymeric backbone elasticity, polymerization degree and spacer length. We have produced bulk and thin film aligned samples, stable at room temperature, characterized by an optical uniaxial anisotropy, with a director order parameter S D ∼0.9999.
Recently, we have reported the synthesis and ring-opening metathesis polymerization of enantiomer... more Recently, we have reported the synthesis and ring-opening metathesis polymerization of enantiomerically pure and racemic methyl-N-(1-phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate. In this paper, we present a new optically active 2-azanorbornene derivative that undergoes ring-opening metathesis polymerization in the presence of molybdenum alkylidene initiators of the type Mo(CH-t-Bu) (NAr)(OR2). Enantiomerically pure (1-phenylethyl)-N-(1-phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene-3-carboxamide 1 can be obtained through an asymmetric Lewis-acid-catalyzed Diels–Alder reaction of cyclopentadiene with
Biobased and biodegradable polymers (BBDs) such as poly(3-hydroxy-butyrate), PHB, and poly(3-hydr... more Biobased and biodegradable polymers (BBDs) such as poly(3-hydroxy-butyrate), PHB, and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are considered attractive alternatives to fossil-based plastic materials since they are more environmentally friendly. One major problem with these compounds is their high crystallinity and brittleness. In order to generate softer materials without using fossil-based plasticizers, the suitability of natural rubber (NR) as an impact modifier was investigated in PHBV blends. Mixtures with varying proportions of NR and PHBV were generated, and samples were prepared by mechanical mixing (roll mixer and/or internal mixer) and cured by radical C–C crosslinking. The obtained specimens were investigated with respect to their chemical and physical characteristics, applying a variety of different methods such as size exclusion chromatography, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal analysis, XRD, and mecha...
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