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Andrea M. Kasko - One of the best experts on this subject based on the ideXlab platform.

  • Biodegradable Aromatic–Aliphatic Poly(Ester–amides) from Monolignol-Based Ester Dimers
    ACS Sustainable Chemistry & Engineering, 2018
    Co-Authors: Brianna M. Upton, Andrea M. Kasko
    Abstract:

    Biobased polymers with tunable properties have received increased attention in the literature due to a decline in petroleum reserves. Owing to its low cost, abundance, and Aromatic structure, lignin has great potential as a feedstock for value-added polymeric products. In this work, we condensed carboxylic acid precursors with monolignols to generate reactive dimers for polymer synthesis. Three different Aromatic Ester dimers, each corresponding to a different monolignol, were synthesized and characterized. The dicarboxylic acid dimers were converted to the corresponding diacid chloride in situ with thionyl chloride, and a series of poly(Ester–amides) were synthesized via interfacial polymerization of these diacid chlorides with seven different aliphatic or Aromatic diamines. The thermal properties (decomposition, glass transition temperature, and melting temperature) and hydrolytic stability in acidic and neutral aqueous conditions of the resulting polymers were studied.

  • biodegradable Aromatic aliphatic poly Ester amides from monolignol based Ester dimers
    ACS Sustainable Chemistry & Engineering, 2018
    Co-Authors: Brianna M. Upton, Andrea M. Kasko
    Abstract:

    Biobased polymers with tunable properties have received increased attention in the literature due to a decline in petroleum reserves. Owing to its low cost, abundance, and Aromatic structure, lignin has great potential as a feedstock for value-added polymeric products. In this work, we condensed carboxylic acid precursors with monolignols to generate reactive dimers for polymer synthesis. Three different Aromatic Ester dimers, each corresponding to a different monolignol, were synthesized and characterized. The dicarboxylic acid dimers were converted to the corresponding diacid chloride in situ with thionyl chloride, and a series of poly(Ester–amides) were synthesized via interfacial polymerization of these diacid chlorides with seven different aliphatic or Aromatic diamines. The thermal properties (decomposition, glass transition temperature, and melting temperature) and hydrolytic stability in acidic and neutral aqueous conditions of the resulting polymers were studied.

Wolfgang Kern - One of the best experts on this subject based on the ideXlab platform.

  • wavelength selective refractive index modulation in a romp derived polymer bearing phenyl and ortho nitrobenzyl Ester groups
    Journal of Materials Chemistry C, 2013
    Co-Authors: Matthias Edler, Wolfgang Kern, Gregor Trimmel, Stefan Mayrbrugger, Alexander Fian, Simone Radl, Thomas Grießer
    Abstract:

    Patterning and tuning of the refractive index in polymers by means of UV-light is of great interest for optical applications such as polymeric waveguides or optical data storage devices. In this contribution, we report on the synthesis of a polynorbornene based copolymer bearing ortho-nitrobenzyl and phenyl Ester groups capable of undergoing the photo-induced cleavage reaction and in a subsequent step optionally the photo-Fries rearrangement upon irradiation with UV-light. The photoreaction of these Aromatic Ester groups was investigated by means of FTIR, UV-VIS and spectroscopic ellipsometry. Due to the difference in UV absorption of the photoreactive units, the o-nitrobenzyl Ester can be selectively excited by UV-light above 300 nm, while a subsequent illumination with 254 nm induces the photo-Fries rearrangement of the remaining phenyl Ester groups. The structural changes in the chemical composition upon UV illumination lead to significant changes in the refractive index of the polymeric materials. Whilst the photo-Fries rearrangement of the phenyl Ester groups causes a remarkable increase in the refractive index, it was found that the photo-induced cleavage reaction of ortho-nitrobenzyl Ester moieties causes a decrease of the refractive index. This fact enables a selective tailoring of the refractive index by the choice of the applied wavelength. In addition, a two-step irradiation procedure using a sequence of different wavelengths provides the possibility of erasing and even inverting the index contrast.

  • selected polymers that contain Aromatic Ester units synthesis photoreactions and refractive index modulation
    Macromolecular Chemistry and Physics, 2007
    Co-Authors: Ute Daschiel, Georg Jakopic, Thomas Höfler, Volker Schmidt, Wolfgang Kern
    Abstract:

    Photoreactive polymers bearing aliphatic and Aromatic Esters of 4-(N,N-diphenyl-amino)phenol in the side chain, poly[4-(N,N-diphenylamino)phenyl acrylate] (P1) and poly[4-(N,N-diphenylamino)phenyl 4-vinylbenzoate] (P2), are prepared from their monomers by free radical polymerization. In addition, poly[naphthalene-1-yl 4-vinylbenzoate] is synthesized (P3). These materials absorb UV light up to 2=350 nm. The polymers P1-P3 as well as low-molecular-weight model compounds are investigated with respect to their photoreactions under UV illumination. It is found that decarboxylation is the dominant reaction and that the photo-Fries rearrangement occurs as a minor reaction. The fully Aromatic Ester units in P2 are more reactive than the Ester units in P1. In the polymers, decarboxylation proceeds more efficiently than in the low-molecular-weight model compounds. Upon UV illumination of the polymers, large increases of the refractive index are observed (Δn 450 up to +0.07). This is in agreement with the structural changes in the polymers after irradiation as calculated from group contributions to molar refraction. A preliminary investigation under 610 nm fs laser irradiation indicates that refractive index patterns can be produced by two-photon effects (TPA). The polymers are of potential interest for applications in the field of optical waveguides.

  • UV reactive polymers for refractive index modulation based on the photo-Fries rearrangement
    Polymer, 2007
    Co-Authors: Thomas Höfler, Thomas Grießer, X. Gstrein, Gregor Trimmel, Georg Jakopic, Wolfgang Kern
    Abstract:

    Abstract In this study we report on the synthesis and characterization of photoreactive polymers which display large changes in their refractive index upon UV irradiation. These polymers contain Aromatic Ester groups which undergo a photo-Fries rearrangement from aryl Esters to hydroxyketones. The polymers under investigation were poly(4-acetoxystyrene) and two derivatives of polynorbornene, poly(bicyclo[2.2.1]hept-5-ene-2-carboxylic acid, phenyl Ester) and poly(bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenyl Ester). The kinetics of the photoreaction was studied by FTIR spectroscopy. Ellipsometric measurements of thin films showed that the photo-Fries rearrangement causes a large increase of the refractive indices in these polymers (between +0.03 and +0.05). The modulation of the refractive index is of interest for applications in the field of optics and data storage. The photoreaction also leads to an increase in surface energy as evidenced by contact angle measurements with water and diiodomethane as test liquids.

Brianna M. Upton - One of the best experts on this subject based on the ideXlab platform.

  • Biodegradable Aromatic–Aliphatic Poly(Ester–amides) from Monolignol-Based Ester Dimers
    ACS Sustainable Chemistry & Engineering, 2018
    Co-Authors: Brianna M. Upton, Andrea M. Kasko
    Abstract:

    Biobased polymers with tunable properties have received increased attention in the literature due to a decline in petroleum reserves. Owing to its low cost, abundance, and Aromatic structure, lignin has great potential as a feedstock for value-added polymeric products. In this work, we condensed carboxylic acid precursors with monolignols to generate reactive dimers for polymer synthesis. Three different Aromatic Ester dimers, each corresponding to a different monolignol, were synthesized and characterized. The dicarboxylic acid dimers were converted to the corresponding diacid chloride in situ with thionyl chloride, and a series of poly(Ester–amides) were synthesized via interfacial polymerization of these diacid chlorides with seven different aliphatic or Aromatic diamines. The thermal properties (decomposition, glass transition temperature, and melting temperature) and hydrolytic stability in acidic and neutral aqueous conditions of the resulting polymers were studied.

  • biodegradable Aromatic aliphatic poly Ester amides from monolignol based Ester dimers
    ACS Sustainable Chemistry & Engineering, 2018
    Co-Authors: Brianna M. Upton, Andrea M. Kasko
    Abstract:

    Biobased polymers with tunable properties have received increased attention in the literature due to a decline in petroleum reserves. Owing to its low cost, abundance, and Aromatic structure, lignin has great potential as a feedstock for value-added polymeric products. In this work, we condensed carboxylic acid precursors with monolignols to generate reactive dimers for polymer synthesis. Three different Aromatic Ester dimers, each corresponding to a different monolignol, were synthesized and characterized. The dicarboxylic acid dimers were converted to the corresponding diacid chloride in situ with thionyl chloride, and a series of poly(Ester–amides) were synthesized via interfacial polymerization of these diacid chlorides with seven different aliphatic or Aromatic diamines. The thermal properties (decomposition, glass transition temperature, and melting temperature) and hydrolytic stability in acidic and neutral aqueous conditions of the resulting polymers were studied.

Thomas Höfler - One of the best experts on this subject based on the ideXlab platform.

  • selected polymers that contain Aromatic Ester units synthesis photoreactions and refractive index modulation
    Macromolecular Chemistry and Physics, 2007
    Co-Authors: Ute Daschiel, Georg Jakopic, Thomas Höfler, Volker Schmidt, Wolfgang Kern
    Abstract:

    Photoreactive polymers bearing aliphatic and Aromatic Esters of 4-(N,N-diphenyl-amino)phenol in the side chain, poly[4-(N,N-diphenylamino)phenyl acrylate] (P1) and poly[4-(N,N-diphenylamino)phenyl 4-vinylbenzoate] (P2), are prepared from their monomers by free radical polymerization. In addition, poly[naphthalene-1-yl 4-vinylbenzoate] is synthesized (P3). These materials absorb UV light up to 2=350 nm. The polymers P1-P3 as well as low-molecular-weight model compounds are investigated with respect to their photoreactions under UV illumination. It is found that decarboxylation is the dominant reaction and that the photo-Fries rearrangement occurs as a minor reaction. The fully Aromatic Ester units in P2 are more reactive than the Ester units in P1. In the polymers, decarboxylation proceeds more efficiently than in the low-molecular-weight model compounds. Upon UV illumination of the polymers, large increases of the refractive index are observed (Δn 450 up to +0.07). This is in agreement with the structural changes in the polymers after irradiation as calculated from group contributions to molar refraction. A preliminary investigation under 610 nm fs laser irradiation indicates that refractive index patterns can be produced by two-photon effects (TPA). The polymers are of potential interest for applications in the field of optical waveguides.

  • UV reactive polymers for refractive index modulation based on the photo-Fries rearrangement
    Polymer, 2007
    Co-Authors: Thomas Höfler, Thomas Grießer, X. Gstrein, Gregor Trimmel, Georg Jakopic, Wolfgang Kern
    Abstract:

    Abstract In this study we report on the synthesis and characterization of photoreactive polymers which display large changes in their refractive index upon UV irradiation. These polymers contain Aromatic Ester groups which undergo a photo-Fries rearrangement from aryl Esters to hydroxyketones. The polymers under investigation were poly(4-acetoxystyrene) and two derivatives of polynorbornene, poly(bicyclo[2.2.1]hept-5-ene-2-carboxylic acid, phenyl Ester) and poly(bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenyl Ester). The kinetics of the photoreaction was studied by FTIR spectroscopy. Ellipsometric measurements of thin films showed that the photo-Fries rearrangement causes a large increase of the refractive indices in these polymers (between +0.03 and +0.05). The modulation of the refractive index is of interest for applications in the field of optics and data storage. The photoreaction also leads to an increase in surface energy as evidenced by contact angle measurements with water and diiodomethane as test liquids.

Thomas Grießer - One of the best experts on this subject based on the ideXlab platform.

  • wavelength selective refractive index modulation in a romp derived polymer bearing phenyl and ortho nitrobenzyl Ester groups
    Journal of Materials Chemistry C, 2013
    Co-Authors: Matthias Edler, Wolfgang Kern, Gregor Trimmel, Stefan Mayrbrugger, Alexander Fian, Simone Radl, Thomas Grießer
    Abstract:

    Patterning and tuning of the refractive index in polymers by means of UV-light is of great interest for optical applications such as polymeric waveguides or optical data storage devices. In this contribution, we report on the synthesis of a polynorbornene based copolymer bearing ortho-nitrobenzyl and phenyl Ester groups capable of undergoing the photo-induced cleavage reaction and in a subsequent step optionally the photo-Fries rearrangement upon irradiation with UV-light. The photoreaction of these Aromatic Ester groups was investigated by means of FTIR, UV-VIS and spectroscopic ellipsometry. Due to the difference in UV absorption of the photoreactive units, the o-nitrobenzyl Ester can be selectively excited by UV-light above 300 nm, while a subsequent illumination with 254 nm induces the photo-Fries rearrangement of the remaining phenyl Ester groups. The structural changes in the chemical composition upon UV illumination lead to significant changes in the refractive index of the polymeric materials. Whilst the photo-Fries rearrangement of the phenyl Ester groups causes a remarkable increase in the refractive index, it was found that the photo-induced cleavage reaction of ortho-nitrobenzyl Ester moieties causes a decrease of the refractive index. This fact enables a selective tailoring of the refractive index by the choice of the applied wavelength. In addition, a two-step irradiation procedure using a sequence of different wavelengths provides the possibility of erasing and even inverting the index contrast.

  • UV reactive polymers for refractive index modulation based on the photo-Fries rearrangement
    Polymer, 2007
    Co-Authors: Thomas Höfler, Thomas Grießer, X. Gstrein, Gregor Trimmel, Georg Jakopic, Wolfgang Kern
    Abstract:

    Abstract In this study we report on the synthesis and characterization of photoreactive polymers which display large changes in their refractive index upon UV irradiation. These polymers contain Aromatic Ester groups which undergo a photo-Fries rearrangement from aryl Esters to hydroxyketones. The polymers under investigation were poly(4-acetoxystyrene) and two derivatives of polynorbornene, poly(bicyclo[2.2.1]hept-5-ene-2-carboxylic acid, phenyl Ester) and poly(bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid, diphenyl Ester). The kinetics of the photoreaction was studied by FTIR spectroscopy. Ellipsometric measurements of thin films showed that the photo-Fries rearrangement causes a large increase of the refractive indices in these polymers (between +0.03 and +0.05). The modulation of the refractive index is of interest for applications in the field of optics and data storage. The photoreaction also leads to an increase in surface energy as evidenced by contact angle measurements with water and diiodomethane as test liquids.