Dataset Information

Colorless Semi-Alicyclic Copolyimides with High Thermal Stability and Solubility.

ABSTRACT: A series of colorless copolyimide films with high thermal stability and good solubility are synthesized from (trifluoromethyl)biphenyl-4,4'-diamine (TFMB) with different 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) to 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane (6FDA) dianhydride mole ratios through one-pot solution polycondensation. These copolyimide films exhibit excellent optical transparency (T₄₀₀ > 90% and ?₀ ~305-333 nm) with a thickness of 15 ?m and good solubility in most organic solvents. The excellent optical properties are mainly attributed to the low inter- and intra-molecular charge transfer interactions due to the alicyclic structure and the strong electronegative CF₃ groups. The glass transition temperature increases from 332 to 352 °C with increasing HPMDA content in the copolymers, while the thermal decomposition temperature is improved with increasing 6FDA content. These results indicate that the copolyimide films can be successfully utilized in the development of novel heat-resistant plastic substrates for the optoelectronic engineering applications.

SUBMITTER: Lan Z

PROVIDER: S-EPMC6723692 | biostudies-literature | 2019 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Colorless Semi-Alicyclic Copolyimides with High Thermal Stability and Solubility.

Lan Zhongxu Z Li Chunyu C Yu Yanlei Y Wei Jia J

Polymers 20190807 8

A series of colorless copolyimide films with high thermal stability and good solubility are synthesized from (trifluoromethyl)biphenyl-4,4'-diamine (TFMB) with different 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA) to 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane (6FDA) dianhydride mole ratios through one-pot solution polycondensation. These copolyimide films exhibit excellent optical transparency (T400 > 90% and λ0 ~305-333 nm) with a thickness of ...[more]

PMID: 31394813

Similar Datasets

Project description:Transparent polyimides (PI) films with outstanding overall performance are attractive for next generation optoelectronic and microelectronic applications. Semi-alicyclic PIs derived from alicyclic dianhydrides and aromatic diamines have proved effective to prepare transparent PIs with high transmittance. To optimize the combined properties of semi-alicyclic PIs, incorporating bulky trifluoromethyl groups into the backbones is regarded as a powerful tool. However, the lack of fundamental understanding of structure-property relationships of fluorinated semi-alicyclic PIs constrains the design and engineering of advanced films for such challenging applications. Herein, a series of semi-alicyclic PIs derived from alicyclic dianhydrides and trifluoromethyl-containing aromatic diamines was synthesized by solution polycondensation at high temperature. The effects of alicyclic structures and bulky trifluoromethyl groups on thermal, dielectric and optical properties of PIs were investigated systematically. These PI films had excellent solubility, low water absorption and good mechanical property. They showed high heat resistance with Tg in the range of 294-390 °C. It is noted that tensile strength and thermal stability were greatly affected by the rigid linkages and alicyclic moieties, respectively. These films exhibited obviously low refractive indices and significantly reduced dielectric constants from 2.61 to 2.76, together with low optical birefringence and dielectric anisotropy. Highly transparent films exhibited cutoff wavelength even as low as 298 nm and transmittance at 500 nm over 85%, displaying almost colorless appearance with yellowness index (b*) below 4.2. The remarkable optical improvement should be mainly ascribed to both weak electron-accepting alicyclic units and bulky electron-withdrawing trifluoromethyl or sulfone groups. The present work provides an effective strategy to design molecular structures of optically transparent PIs for a trade-off between solution-processability, low water uptake, good toughness, high heat resistance, low dielectric constant and excellent optical transparency.

Project description:The extreme pH and protease-rich environment of the upper gastrointestinal tract is a major obstacle facing orally-administered protein therapeutics, including antibodies. Through protein engineering, several Clostridium difficile toxin A-specific heavy chain antibody variable domains (V(H)Hs) were expressed with an additional disulfide bond by introducing Ala/Gly54Cys and Ile78Cys mutations. Mutant antibodies were compared to their wild-type counterparts with respect to expression yield, non-aggregation status, affinity for toxin A, circular dichroism (CD) structural signatures, thermal stability, protease resistance, and toxin A-neutralizing capacity. The mutant V(H)Hs were found to be well expressed, although with lower yields compared to wild-type counterparts, were non-aggregating monomers, retained low nM affinity for toxin A, albeit the majority showed somewhat reduced affinity compared to wild-type counterparts, and were capable of in vitro toxin A neutralization in cell-based assays. Far-UV and near-UV CD spectroscopy consistently showed shifts in peak intensity and selective peak minima for wild-type and mutant V(H)H pairs; however, the overall CD profile remained very similar. A significant increase in the thermal unfolding midpoint temperature was observed for all mutants at both neutral and acidic pH. Digestion of the V(H)Hs with the major gastrointestinal proteases, at biologically relevant concentrations, revealed a significant increase in pepsin resistance for all mutants and an increase in chymotrypsin resistance for the majority of mutants. Mutant V(H)H trypsin resistance was similar to that of wild-type V(H)Hs, although the trypsin resistance of one V(H)H mutant was significantly reduced. Therefore, the introduction of a second disulfide bond in the hydrophobic core not only increases V(H)H thermal stability at neutral pH, as previously shown, but also represents a generic strategy to increase V(H)H stability at low pH and impart protease resistance, with only minor perturbations in target binding affinities. These are all desirable characteristics for the design of protein-based oral therapeutics.

Dataset Information

Colorless Semi-Alicyclic Copolyimides with High Thermal Stability and Solubility.

Publications

Colorless Semi-Alicyclic Copolyimides with High Thermal Stability and Solubility.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure