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Keigo Aoi - One of the best experts on this subject based on the ideXlab platform.

  • Biodegradable polymers based on renewable resources. V. Synthesis and biodegradation behavior of poly(ester amide)s composed of 1,4:3,6‐dianhydro‐D‐glucitol, α‐amino Acid, and Aliphatic Dicarboxylic Acid units
    Journal of Applied Polymer Science, 2001
    Co-Authors: Masahiko Okada, Masashi Yamada, Makito Yokoe, Keigo Aoi
    Abstract:

    A series of poly(ester amide)s were synthesized by solution polycondensations of various combinations of p-toluenesulfonic Acid salts of O,O′-bis(α-aminoacyl)-1,4:3,6-dianhydro-D-glucitol and bis(p-nitrophenyl) esters of Aliphatic Dicarboxylic Acids with the methylene chain lengths of 4–10. The p-toluenesulfonic Acid salts were obtained by the reactions of 1,4:3,6-dianhydro-D-glucitol with alanine, glycine, and glycylglycine, respectively, in the presence of p-toluenesulfonic Acid. The polycondensations were carried out in N-methylpyrrolidone at 40°C in the presence of triethylamine, giving poly(ester amide)s having number-average molecular weights up to 3.8 × 104. Their structures were confirmed by FTIR, 1H-NMR, and 13C-NMR spectroscopy. Most of these poly(ester amide)s are amorphous, except those containing sebacic Acid and glycine or glycylglycine units, which are semicrystalline. All these poly(ester amide)s are soluble in a variety of polar solvents such as dimethyl sulfoxide, N,N-dimethylformamide, 2,2,2-trifluoroethanol, m-cresol, pyridine, and trifluoroacetic Acid. Soil burial degradation tests, BOD measurements in an activated sludge, and enzymatic degradation tests using Porcine pancreas lipase and papain indicated that these poly(ester amide)s are biodegradable, and that their biodegradability markedly depends on the molecular structure. The poly(ester amide)s were, in general, degraded more slowly than the corresponding polyesters having the same Aliphatic Dicarboxylic Acid units, both in composted soil and in an activated sludge. In the enzymatic degradation, some poly(ester amide)s containing Dicarboxylic Acid components with shorter methylene chain lengths were degraded more readily than the corresponding polyesters with Porcine pancreas lipase, whereas most of the poly(ester amide)s were degraded more rapidly than the corresponding polyesters with papain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2721–2734, 2001

  • biodegradable polymers based on renewable resources v synthesis and biodegradation behavior of poly ester amide s composed of 1 4 3 6 dianhydro d glucitol α amino Acid and Aliphatic Dicarboxylic Acid units
    Journal of Applied Polymer Science, 2001
    Co-Authors: Masahiko Okada, Masashi Yamada, Makito Yokoe, Keigo Aoi
    Abstract:

    A series of poly(ester amide)s were synthesized by solution polycondensations of various combinations of p-toluenesulfonic Acid salts of O,O′-bis(α-aminoacyl)-1,4:3,6-dianhydro-D-glucitol and bis(p-nitrophenyl) esters of Aliphatic Dicarboxylic Acids with the methylene chain lengths of 4–10. The p-toluenesulfonic Acid salts were obtained by the reactions of 1,4:3,6-dianhydro-D-glucitol with alanine, glycine, and glycylglycine, respectively, in the presence of p-toluenesulfonic Acid. The polycondensations were carried out in N-methylpyrrolidone at 40°C in the presence of triethylamine, giving poly(ester amide)s having number-average molecular weights up to 3.8 × 104. Their structures were confirmed by FTIR, 1H-NMR, and 13C-NMR spectroscopy. Most of these poly(ester amide)s are amorphous, except those containing sebacic Acid and glycine or glycylglycine units, which are semicrystalline. All these poly(ester amide)s are soluble in a variety of polar solvents such as dimethyl sulfoxide, N,N-dimethylformamide, 2,2,2-trifluoroethanol, m-cresol, pyridine, and trifluoroacetic Acid. Soil burial degradation tests, BOD measurements in an activated sludge, and enzymatic degradation tests using Porcine pancreas lipase and papain indicated that these poly(ester amide)s are biodegradable, and that their biodegradability markedly depends on the molecular structure. The poly(ester amide)s were, in general, degraded more slowly than the corresponding polyesters having the same Aliphatic Dicarboxylic Acid units, both in composted soil and in an activated sludge. In the enzymatic degradation, some poly(ester amide)s containing Dicarboxylic Acid components with shorter methylene chain lengths were degraded more readily than the corresponding polyesters with Porcine pancreas lipase, whereas most of the poly(ester amide)s were degraded more rapidly than the corresponding polyesters with papain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2721–2734, 2001

  • 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
    Journal of Applied Polymer Science, 2000
    Co-Authors: Masahiko Okada, Kenji Tsunoda, Kouji Tachikawa, Keigo Aoi
    Abstract:

    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

  • 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
    Journal of Applied Polymer Science, 2000
    Co-Authors: Masahiko Okada, Kenji Tsunoda, Kouji Tachikawa, Keigo Aoi
    Abstract:

    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

  • biodegradable polymers based on renewable resources iii copolyesters composed of 1 4 3 6 dianhydro d glucitol 1 1 bis 5 carboxy 2 furyl ethane and Aliphatic Dicarboxylic Acid units
    Journal of Applied Polymer Science, 1999
    Co-Authors: Masahiko Okada, Kouji Tachikawa, Keigo Aoi
    Abstract:

    Various copolyesters were synthesized by bulk polycondensation of the respective combinations of 1,4;3,6-dianhydro-D-glucitol (1) as the diol component and 1,1-bis[5-(methoxycarbonyl)-2-furyl]ethane (3b) and seven dimethyl dialkanoates with methylene chain lengths of 4, 5, 6, 7, 8, 10, and 12 (4a–4g) as the Dicarboxylic Acid components. Most of the copolyesters were amorphous, while a copolyester composed of 1, 3b, and dodecanedioic Acid (4g) (3b:4g = 25:75) units as well as homopolyesters derived from 1 and azelaic Acid (4d), sebacic Acid (4e), and dodecandioic Acid (4g), respectively, were partially crystalline. All these homo- and copolyesters were soluble in chloroform, dichloromethane, pyridine, trifluoroacetic Acid, and m-cresol. The number-average molecular weights of these polyesters were estimated to be in the range of 10,000–20,000 by SEC using chloroform as an eluent and standard polystyrene as a reference. The biodegradability of these copolyesters was assessed by enzymatic degradation using four different enzymes in a phosphate buffer solution at 37°C and by soil burial degradation tests in composted soil at 27°C. In general, biodegradability of the copolyesters decreased with increase in the difuran dicarboxylate 3b content. Copolyesters containing sebasic Acid 4e units showed higher biodegradability. Soil burial degradation in the soil that was treated with antibiotics, together with electron microscopic observation, indicated that actinomycetes are mainly responsible for the degradation of the copolyesters containing 3b units in the present soil burial test. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3342–3350, 1999

Michael R. Kessler - One of the best experts on this subject based on the ideXlab platform.

  • Liquid crystalline epoxy networks with exchangeable disulfide bonds.
    Soft matter, 2017
    Co-Authors: Yuehong Zhang, Orlando Rios, Jong K. Keum, Michael R. Kessler
    Abstract:

    A liquid crystalline epoxy network (LCEN) with exchangeable disulfide bonds is synthesized by polymerizing a biphenyl-based epoxy monomer with an Aliphatic Dicarboxylic Acid curing agent containing a disulfide bond. The effect of disulfide bonds on curing behavior and liquid crystalline (LC) phase formation of the LCEN is investigated. The presence of the disulfide bonds results in an increase in the reaction rate, leading to a reduction in liquid crystallinity of the LCEN. In order to promote LC phase formation and stabilize the self-assembled LC domains, a similar Aliphatic Dicarboxylic Acid without the disulfide bond is used as a co-curing agent to reduce the amount of exchangeable disulfide bonds in the system. After optimizing the molar ratio of the two curing agents, the resulting LCEN exhibits improved reprocessability and recyclability because of the disulfide exchange reactions, while preserving LC properties, such as the reversible LC phase transition and macroscopic LC orientation, for shape memory applications.

  • Photoresponsive Liquid Crystalline Epoxy Networks with Shape Memory Behavior and Dynamic Ester Bonds
    2016
    Co-Authors: Orlando Rios, Jong K. Keum, Jihua Chen, Michael R. Kessler
    Abstract:

    Functional polymers are intelligent materials that can respond to a variety of external stimuli. However, these materials have not yet found widespread real world applications because of the difficulties in fabrication and the limited number of functional building blocks that can be incorporated into a material. Here, we demonstrate a simple route to incorporate three functional building blocks (azobenzene chromophores, liquid crystals, and dynamic covalent bonds) into an epoxy-based liquid crystalline network (LCN), in which an azobenzene-based epoxy monomer is polymerized with an Aliphatic Dicarboxylic Acid to create exchangeable ester bonds that can be thermally activated. All three functional building blocks exhibited good compatibility, and the resulting materials exhibits various photomechanical, shape memory, and self-healing properties because of the azobenzene molecules, liquid crystals, and dynamic ester bonds, respectively

Masahiko Okada - One of the best experts on this subject based on the ideXlab platform.

  • Biodegradable polymers based on renewable resources. V. Synthesis and biodegradation behavior of poly(ester amide)s composed of 1,4:3,6‐dianhydro‐D‐glucitol, α‐amino Acid, and Aliphatic Dicarboxylic Acid units
    Journal of Applied Polymer Science, 2001
    Co-Authors: Masahiko Okada, Masashi Yamada, Makito Yokoe, Keigo Aoi
    Abstract:

    A series of poly(ester amide)s were synthesized by solution polycondensations of various combinations of p-toluenesulfonic Acid salts of O,O′-bis(α-aminoacyl)-1,4:3,6-dianhydro-D-glucitol and bis(p-nitrophenyl) esters of Aliphatic Dicarboxylic Acids with the methylene chain lengths of 4–10. The p-toluenesulfonic Acid salts were obtained by the reactions of 1,4:3,6-dianhydro-D-glucitol with alanine, glycine, and glycylglycine, respectively, in the presence of p-toluenesulfonic Acid. The polycondensations were carried out in N-methylpyrrolidone at 40°C in the presence of triethylamine, giving poly(ester amide)s having number-average molecular weights up to 3.8 × 104. Their structures were confirmed by FTIR, 1H-NMR, and 13C-NMR spectroscopy. Most of these poly(ester amide)s are amorphous, except those containing sebacic Acid and glycine or glycylglycine units, which are semicrystalline. All these poly(ester amide)s are soluble in a variety of polar solvents such as dimethyl sulfoxide, N,N-dimethylformamide, 2,2,2-trifluoroethanol, m-cresol, pyridine, and trifluoroacetic Acid. Soil burial degradation tests, BOD measurements in an activated sludge, and enzymatic degradation tests using Porcine pancreas lipase and papain indicated that these poly(ester amide)s are biodegradable, and that their biodegradability markedly depends on the molecular structure. The poly(ester amide)s were, in general, degraded more slowly than the corresponding polyesters having the same Aliphatic Dicarboxylic Acid units, both in composted soil and in an activated sludge. In the enzymatic degradation, some poly(ester amide)s containing Dicarboxylic Acid components with shorter methylene chain lengths were degraded more readily than the corresponding polyesters with Porcine pancreas lipase, whereas most of the poly(ester amide)s were degraded more rapidly than the corresponding polyesters with papain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2721–2734, 2001

  • biodegradable polymers based on renewable resources v synthesis and biodegradation behavior of poly ester amide s composed of 1 4 3 6 dianhydro d glucitol α amino Acid and Aliphatic Dicarboxylic Acid units
    Journal of Applied Polymer Science, 2001
    Co-Authors: Masahiko Okada, Masashi Yamada, Makito Yokoe, Keigo Aoi
    Abstract:

    A series of poly(ester amide)s were synthesized by solution polycondensations of various combinations of p-toluenesulfonic Acid salts of O,O′-bis(α-aminoacyl)-1,4:3,6-dianhydro-D-glucitol and bis(p-nitrophenyl) esters of Aliphatic Dicarboxylic Acids with the methylene chain lengths of 4–10. The p-toluenesulfonic Acid salts were obtained by the reactions of 1,4:3,6-dianhydro-D-glucitol with alanine, glycine, and glycylglycine, respectively, in the presence of p-toluenesulfonic Acid. The polycondensations were carried out in N-methylpyrrolidone at 40°C in the presence of triethylamine, giving poly(ester amide)s having number-average molecular weights up to 3.8 × 104. Their structures were confirmed by FTIR, 1H-NMR, and 13C-NMR spectroscopy. Most of these poly(ester amide)s are amorphous, except those containing sebacic Acid and glycine or glycylglycine units, which are semicrystalline. All these poly(ester amide)s are soluble in a variety of polar solvents such as dimethyl sulfoxide, N,N-dimethylformamide, 2,2,2-trifluoroethanol, m-cresol, pyridine, and trifluoroacetic Acid. Soil burial degradation tests, BOD measurements in an activated sludge, and enzymatic degradation tests using Porcine pancreas lipase and papain indicated that these poly(ester amide)s are biodegradable, and that their biodegradability markedly depends on the molecular structure. The poly(ester amide)s were, in general, degraded more slowly than the corresponding polyesters having the same Aliphatic Dicarboxylic Acid units, both in composted soil and in an activated sludge. In the enzymatic degradation, some poly(ester amide)s containing Dicarboxylic Acid components with shorter methylene chain lengths were degraded more readily than the corresponding polyesters with Porcine pancreas lipase, whereas most of the poly(ester amide)s were degraded more rapidly than the corresponding polyesters with papain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2721–2734, 2001

  • 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
    Journal of Applied Polymer Science, 2000
    Co-Authors: Masahiko Okada, Kenji Tsunoda, Kouji Tachikawa, Keigo Aoi
    Abstract:

    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

  • 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
    Journal of Applied Polymer Science, 2000
    Co-Authors: Masahiko Okada, Kenji Tsunoda, Kouji Tachikawa, Keigo Aoi
    Abstract:

    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

  • biodegradable polymers based on renewable resources iii copolyesters composed of 1 4 3 6 dianhydro d glucitol 1 1 bis 5 carboxy 2 furyl ethane and Aliphatic Dicarboxylic Acid units
    Journal of Applied Polymer Science, 1999
    Co-Authors: Masahiko Okada, Kouji Tachikawa, Keigo Aoi
    Abstract:

    Various copolyesters were synthesized by bulk polycondensation of the respective combinations of 1,4;3,6-dianhydro-D-glucitol (1) as the diol component and 1,1-bis[5-(methoxycarbonyl)-2-furyl]ethane (3b) and seven dimethyl dialkanoates with methylene chain lengths of 4, 5, 6, 7, 8, 10, and 12 (4a–4g) as the Dicarboxylic Acid components. Most of the copolyesters were amorphous, while a copolyester composed of 1, 3b, and dodecanedioic Acid (4g) (3b:4g = 25:75) units as well as homopolyesters derived from 1 and azelaic Acid (4d), sebacic Acid (4e), and dodecandioic Acid (4g), respectively, were partially crystalline. All these homo- and copolyesters were soluble in chloroform, dichloromethane, pyridine, trifluoroacetic Acid, and m-cresol. The number-average molecular weights of these polyesters were estimated to be in the range of 10,000–20,000 by SEC using chloroform as an eluent and standard polystyrene as a reference. The biodegradability of these copolyesters was assessed by enzymatic degradation using four different enzymes in a phosphate buffer solution at 37°C and by soil burial degradation tests in composted soil at 27°C. In general, biodegradability of the copolyesters decreased with increase in the difuran dicarboxylate 3b content. Copolyesters containing sebasic Acid 4e units showed higher biodegradability. Soil burial degradation in the soil that was treated with antibiotics, together with electron microscopic observation, indicated that actinomycetes are mainly responsible for the degradation of the copolyesters containing 3b units in the present soil burial test. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3342–3350, 1999

Hans R. Kricheldorf - One of the best experts on this subject based on the ideXlab platform.

  • Macrocycles. 19. Cyclization in the nematic phase? Polyesters derived from hydroquinone 4-hydroxybenzoate and Aliphatic Dicarboxylic Acids
    Macromolecules, 2002
    Co-Authors: Hans R. Kricheldorf, Martin Richter, Gert Schwarz
    Abstract:

    Silylated hydroquinone 4-hydroxybenzoate (HHB) was polycondensed with Aliphatic Dicarboxylic Acid dichlorides (ADADs) in bulk at temperature up to 240 °C. These polycondensations proceeded in the nematic phase, and both transesterification and backbiting degradation were avoided as evidenced by 1 H NMR spectroscopy. The nematic LC phases were characterized by optical microscopy and DSC measurements. The MALDI-TOF mass spectra revealed the formation ofeven-membered cycles (in addition to linear oligomers), whereas odd-membered cycles were almost absent. When the reaction mixture was slightly diluted with 1-chloronaphthalene, so that the polycondensation proceeded in the isotropic phase, odd-membered cycles with a predominance of the cyclic trimer were found. When free HHB was polycondensed with ADADs in 1-chloronaphthalene at 220 °C in 1,2-dichlorobenzene at 190 °C or in the presence of pyridine at 5-10 °C, again odd-membered cycles were found. Obviously, the nematic phase enforces a parallel alignment of polyester chains with strong electronic interaction of neighboring mesogens, so that cyclization can only occur in the case of even-membered chains via hairpin conformations of the Aliphatic spacers.

  • New polymer syntheses. CIX. Biodegradable, alternating copolyesters of terephthalic Acid, Aliphatic Dicarboxylic Acids, and alkane diols
    Journal of Polymer Science Part A: Polymer Chemistry, 2001
    Co-Authors: Abbas-ali Shaik, Hans R. Kricheldorf, Martin Richter, Ralph-p. Krüger
    Abstract:

    Copolyesters with an alternating sequence of terephthalic Acid and Aliphatic Dicarboxylic Acids were prepared with three different methods. First, Dicarboxylic Acid dichlorides were reacted with bis(2-hydroxyethyl)terephthalate (BHET) in refluxing 1,2-dichlorobenzene. Second, the same monomers were polycondensed at 0–20 °C in the presence of pyridine. Third, Dicarboxylic Acid dichlorides and silylated BHET were polycondensed in bulk. Only this third method gave satisfactory molecular weights. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed that the copolyesters prepared by the pyridine and silyl methods might have contained considerable fractions of cyclic oligoesters and polyesters despite the absence of transesterification and backbiting processes. The alternating sequences and thermal properties were characterized with 1H NMR spectroscopy and differential scanning calorimetry measurements, respectively. In agreement with the alternating sequence, all copolyesters proved to be crystalline, but the crystallization was extremely slow [slower than that of poly(ethylene terephthalate)]. A second series of alternating copolyesters was prepared by the polycondensation of silylated bis(4-hydroxybut- yl)terephthalate with various Aliphatic Dicarboxylic Acid dichlorides. The resulting copolyesters showed significantly higher rates of crystallization, and the melting temperatures were higher than those of the BHET-based copolyesters. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3371–3382, 2001

  • Macrocycles. 15. The Role of Cyclization in Kinetically Controlled Polycondensations. 1. Polyester Syntheses
    Macromolecules, 2001
    Co-Authors: Hans R. Kricheldorf, Michael Rabenstein, Michael Maskos, Manfred Schmidt
    Abstract:

    Various diols were polycondensed with Dicarboxylic dichlorides in the presence of pyridine or γ-picoline. Aliphatic Dicarboxylic Acid dichlorides were reacted with 1,4-butanediol, catechol resorcin...

  • macrocycles 11 polycondensations of Aliphatic Dicarboxylic Acid dichlorides with catechol or bis trimethylsilyl catechol
    Journal of Polymer Science Part A, 1999
    Co-Authors: Hans R. Kricheldorf, Aleksandra Lorenc, Jochen Spickermann, Michael Maskos
    Abstract:

    When O,O′-Bistrimethylsilyl catechol (BTSC) was polycondensed with adipoyl chloride in o-dichlorobenzene the 10-membered cyclic monomer was the main reaction product regardless of the concentration. Even the polycondensation in bulk yielded the macrocyclic monomer as the main product. Polycondensations of free catechol yielded similar results. Polycondensations of catechol or BTSC with suberoyl chloride, sebacoyl chloride, and decane-1,10-dicarbonyl chloride in concentrated solutions or in bulk yielded cyclic oligoesters as the main reaction products whereas linear oligoesters or polyesters were a minority. Polycondensations of BTSC with the longer diAcid dichlorides in refluxing o-dichlorobenzene under high dilution yielded the 12–14-membered cyclic monomers as the main products. The molecular weights and the cyclic structure of all reaction products were characterized by mass spectrometery, fast-atom bombardment (FAB) or MALDI-TOF mass spectrometry. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3861–3870, 1999

Alice Mija - One of the best experts on this subject based on the ideXlab platform.

  • Influence of the Presence of Disulphide Bonds in Aromatic or Aliphatic Dicarboxylic Acid Hardeners Used to Produce Reprocessable Epoxidized Thermosets
    Polymers, 2021
    Co-Authors: Chiara Di Mauro, Alice Mija
    Abstract:

    The design of polymers from renewable resources with recycling potential comes from economic and environmental problems. This work focused on the impact of disulphide bonds in the Dicarboxylic Acids reactions with three epoxidized vegetable oils (EVOs). For the first time, the comparison between aromatic vs. Aliphatic Dicarboxylic Acids, containing or not S–S bonds with EVOs was discussed and evaluated by dynamic scanning calorimetry. The obtained thermosets showed reprocessability, by the dual dynamic exchange mechanism. The virgin and reprocessed materials were characterized and the thermomechanical properties were compared. The thermosets derived from EVOs with high epoxy content combined with aromatic diAcids containing disulphide bridges showed high glass transition values (~111 °C), high crosslink densities and good solvent stability.