In situ melt polycondensation was proposed to prepare biodegradable aliphatic-aromatic copolyesters/nano-SiO2 hybrids based on terephthalic acid （TPA）, poly（L-lactic acid） oligomer （OLLA）, 1,4-butanediol （BDO）...In situ melt polycondensation was proposed to prepare biodegradable aliphatic-aromatic copolyesters/nano-SiO2 hybrids based on terephthalic acid （TPA）, poly（L-lactic acid） oligomer （OLLA）, 1,4-butanediol （BDO） and nano-SiO2. TEM and FT-IR characterizations confirmed that TPA, OLLA and BDO copolymerized to obtain biodegradable copolyesters, poly（butylene terepbthalate-co-lactate） （PBTL）, and the abundant hydroxyl groups on the surface of nano-SiO2 provided potential sites for in situ grafting with the simultaneous resulted PBTL. The nano-SiO2 particles were chemically wrapped with PBTL to form PBTL/nano- SiO2 hybrids. Due to the good dispersion and interfacial adhesion of nano-SiO2 particles with the copolyester matrix, the tensile strength and the Young＇s modulus increased from 5.4 and 5.6 MPa for neat PBTL to 16 and 390 MPa for PBTL/nano-SiO2 hybrids with 5 wt.% nano-SiO2, respectively. The mechanical properties of PBTL/nano-SiO2 hybrids were substantially improved.展开更多
A series organosoluble and heterocyclic poly（ether-amide）s （PEA）s were synthesized from a new diamine containing pyridine moiety and four aliphatic-aromatic dicarboxylic acids by direct polycondensation reactions....A series organosoluble and heterocyclic poly（ether-amide）s （PEA）s were synthesized from a new diamine containing pyridine moiety and four aliphatic-aromatic dicarboxylic acids by direct polycondensation reactions. Dicarboxilic acids 4a-4d containing ether groups were synthesized in two step reactions. At first, dialdehydes 3a-3d were synthesized from four dibromo alkanes la-ld and 4-hydroxybenzaldehyde 2, then dicarboxilic acids 4a-4d were synthesized from dialdehydes 3a-3d and malonic acid in a solvent free reaction. On the other hand, the new diamine 8 containing pyridine ring was synthesized in two step reactions. The structures of synthesized monomers and polymers were proven by FTIR, NMR spectroscopy and elemental analysis. Also all of the above polymers were fully characterized by inherent viscosity, solubility tests, gel permeation chromatography （GPC）, differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）. The resulted PEAs have shown good inherent viscosities, solubility and thermal properties.展开更多
To enhance the properties of bio-based polyesters,enabling them to more closely mimic the characteristics of terephthalate-based materials,a series of aliphatic-aromatic copolyesters(P_(1)–P_(4))were synthesized via ...To enhance the properties of bio-based polyesters,enabling them to more closely mimic the characteristics of terephthalate-based materials,a series of aliphatic-aromatic copolyesters(P_(1)–P_(4))were synthesized via melt polycondensation.Diester monomers M and N were synthesized via the Williamson reaction,using lignin-derived 2-methoxyhydroquinone,methyl 4-chloromethylbenzoate,and methyl chloroacetate as starting materials.Hydroquinone bis(2-hydroxyethyl)ether(HQEE)and 1,4-cyclohexanedimethanol(CHDM)were employed as cyclic segments,while 1,4-butanediol(BDO)and 1,6-hexanediol(HDO)served as alkyl segments within the copolymer structures.The novel copolyesters exhibited molecular weights(Mw)in the range of 5.25×10^(4)–5.87×10^(4) g/mol,with polydispersity indices spanning from 2.50–2.66.Evaluation of the structural and thermomechanical properties indicated that the inclusion of alkyl segments induced a reduction in both crystallinity and molecular weight,while significantly improving the flexibility,whereas cyclic segments enhanced the processability of the copolyesters.Copolyesters P_(1) and P_(2),due to the presence of rigid segments(HQEE and CHDM),displayed relatively high glass transition temperatures(Tg>80℃)and melting temperatures(Tm>170℃).Notably,P_(2),incorporating CHDM,exhibited superior elongation properties(272%),attributed to the enhanced chain mobility resulting from its trans-conformation,while P_(1) was found to be likely brittle owing to excessive chain stiffness.Biodegradability assessment using earthworms as bioindicators revealed that the copolyesters demonstrated moderate degradation profiles,with P_(2) exhibiting a degradation rate of 4.82%,followed by P_(4) at 4.07%,P_(3) at 3.65%,and P_(1) at 3.17%.The higher degradation rate of P_(2) was attributed to its relatively larger d-spacing and lower toxicity,which facilitated enzymatic hydrolytic attack by microorganisms.These findings highlight the significance of optimizing the structural chain segments within aliphatic-aromatic copolyesters.By doing so,it is possible to significantly enhance their properties and performance,offering viable bio-based alternatives to petroleum-based polyesters such as polyethylene terephthalate(PET).展开更多
A series of degradable polyesters was synthesized via melt polymerization of 3,6-dioxaoctane-1,8-dioic acid and five different diols,catalyzed by antimony trioxide(Sb_(2)O_(3)).The polymers were characterized by FT-IR...A series of degradable polyesters was synthesized via melt polymerization of 3,6-dioxaoctane-1,8-dioic acid and five different diols,catalyzed by antimony trioxide(Sb_(2)O_(3)).The polymers were characterized by FT-IR and ^(1)H NMR spectroscopy,gel permeation chromatography(GPC)and differential scanning calorimetry(DSC)analysis.The polydispersity index(PDI=M_(w)/M_(n))of the polyesters ranged from 1.55 to 1.99,the weight-average molecular weight(M_(w))from 1.8×10^(4) to 3.2×10^(4) Da,the melting point from 63 to 123℃,and the highest decomposition temperature observed was 363℃.The influence of the structure of the polymer chain on hydrolytic degradability was investigated with tests performed at three different values of pH.The findings obtained provide useful insight for the molecular design and the synthesis of degradable polyesters.展开更多
基金support from the Natural Science Foundation of Ningbo(No.2007A610030)Science and Technology Department of Zhejiang Province(No.2008C11092-2)
文摘In situ melt polycondensation was proposed to prepare biodegradable aliphatic-aromatic copolyesters/nano-SiO2 hybrids based on terephthalic acid （TPA）, poly（L-lactic acid） oligomer （OLLA）, 1,4-butanediol （BDO） and nano-SiO2. TEM and FT-IR characterizations confirmed that TPA, OLLA and BDO copolymerized to obtain biodegradable copolyesters, poly（butylene terepbthalate-co-lactate） （PBTL）, and the abundant hydroxyl groups on the surface of nano-SiO2 provided potential sites for in situ grafting with the simultaneous resulted PBTL. The nano-SiO2 particles were chemically wrapped with PBTL to form PBTL/nano- SiO2 hybrids. Due to the good dispersion and interfacial adhesion of nano-SiO2 particles with the copolyester matrix, the tensile strength and the Young＇s modulus increased from 5.4 and 5.6 MPa for neat PBTL to 16 and 390 MPa for PBTL/nano-SiO2 hybrids with 5 wt.% nano-SiO2, respectively. The mechanical properties of PBTL/nano-SiO2 hybrids were substantially improved.
文摘A series organosoluble and heterocyclic poly（ether-amide）s （PEA）s were synthesized from a new diamine containing pyridine moiety and four aliphatic-aromatic dicarboxylic acids by direct polycondensation reactions. Dicarboxilic acids 4a-4d containing ether groups were synthesized in two step reactions. At first, dialdehydes 3a-3d were synthesized from four dibromo alkanes la-ld and 4-hydroxybenzaldehyde 2, then dicarboxilic acids 4a-4d were synthesized from dialdehydes 3a-3d and malonic acid in a solvent free reaction. On the other hand, the new diamine 8 containing pyridine ring was synthesized in two step reactions. The structures of synthesized monomers and polymers were proven by FTIR, NMR spectroscopy and elemental analysis. Also all of the above polymers were fully characterized by inherent viscosity, solubility tests, gel permeation chromatography （GPC）, differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）. The resulted PEAs have shown good inherent viscosities, solubility and thermal properties.
基金financially supported by State Administration of Foreign Experts Affairs(SAFEA)through the High-End Foreign Expert Program(No.BG2021227001)postdoctoral funding from Wuhan University of Science and Technology(No.105008701)。
文摘To enhance the properties of bio-based polyesters,enabling them to more closely mimic the characteristics of terephthalate-based materials,a series of aliphatic-aromatic copolyesters(P_(1)–P_(4))were synthesized via melt polycondensation.Diester monomers M and N were synthesized via the Williamson reaction,using lignin-derived 2-methoxyhydroquinone,methyl 4-chloromethylbenzoate,and methyl chloroacetate as starting materials.Hydroquinone bis(2-hydroxyethyl)ether(HQEE)and 1,4-cyclohexanedimethanol(CHDM)were employed as cyclic segments,while 1,4-butanediol(BDO)and 1,6-hexanediol(HDO)served as alkyl segments within the copolymer structures.The novel copolyesters exhibited molecular weights(Mw)in the range of 5.25×10^(4)–5.87×10^(4) g/mol,with polydispersity indices spanning from 2.50–2.66.Evaluation of the structural and thermomechanical properties indicated that the inclusion of alkyl segments induced a reduction in both crystallinity and molecular weight,while significantly improving the flexibility,whereas cyclic segments enhanced the processability of the copolyesters.Copolyesters P_(1) and P_(2),due to the presence of rigid segments(HQEE and CHDM),displayed relatively high glass transition temperatures(Tg>80℃)and melting temperatures(Tm>170℃).Notably,P_(2),incorporating CHDM,exhibited superior elongation properties(272%),attributed to the enhanced chain mobility resulting from its trans-conformation,while P_(1) was found to be likely brittle owing to excessive chain stiffness.Biodegradability assessment using earthworms as bioindicators revealed that the copolyesters demonstrated moderate degradation profiles,with P_(2) exhibiting a degradation rate of 4.82%,followed by P_(4) at 4.07%,P_(3) at 3.65%,and P_(1) at 3.17%.The higher degradation rate of P_(2) was attributed to its relatively larger d-spacing and lower toxicity,which facilitated enzymatic hydrolytic attack by microorganisms.These findings highlight the significance of optimizing the structural chain segments within aliphatic-aromatic copolyesters.By doing so,it is possible to significantly enhance their properties and performance,offering viable bio-based alternatives to petroleum-based polyesters such as polyethylene terephthalate(PET).
基金Funded by the Program(BG20190227001)of High-end Foreign Experts of the State Administration of Foreign Experts Affairs(SAFEA)the Coal Conversion and New Carbon Materials Hubei Key Laboratory in Wuhan University of Science and Technology(WKDM201909)。
文摘A series of degradable polyesters was synthesized via melt polymerization of 3,6-dioxaoctane-1,8-dioic acid and five different diols,catalyzed by antimony trioxide(Sb_(2)O_(3)).The polymers were characterized by FT-IR and ^(1)H NMR spectroscopy,gel permeation chromatography(GPC)and differential scanning calorimetry(DSC)analysis.The polydispersity index(PDI=M_(w)/M_(n))of the polyesters ranged from 1.55 to 1.99,the weight-average molecular weight(M_(w))from 1.8×10^(4) to 3.2×10^(4) Da,the melting point from 63 to 123℃,and the highest decomposition temperature observed was 363℃.The influence of the structure of the polymer chain on hydrolytic degradability was investigated with tests performed at three different values of pH.The findings obtained provide useful insight for the molecular design and the synthesis of degradable polyesters.
