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• A novel method of NH 2 -magnetic core coated nanochitosan-COOH shell was prepared. • We report the successful characterization of NCS-structured magnetic nanoparticles. • The presence of amine in the nanostructure coating promoted particle stability. • The dispersity of nanostructure was performed in polar and nonpolar solvents. • The current work highlights the innovative use of nanochitosan-based biomaterials. We developed a novel synthesis method for a multifunctional nanocomposite with amine-functionalized Fe 3 O 4 core coated with carboxylated nanochitosan shells (NH 2 -Fe 3 O 4 @NCS-COOH) via carbodiimide activation. The chemical structures of chitosan and carboxylated nanochitosan (NCS-COOH) were verified by 1H NMR which confirmed the incorporation of citric acid by the formation of the new signal of the CH2 H-atoms. TEM image displayed the synthesized NH 2 -Fe 3 O 4 @NCS-COOH nanoparticles were in a spherical shape with an average size of 100 nm. The results of XRD revealed that NH 2 -Fe 3 O 4 @NCS-COOH have a good crystalline nature with the face center cubic structure and with the average crystallite size of 17 nm. The characterization using VSM showed that the magnetic nanoparticle had superparamagnetic behavior and the saturation magnetization was up to 30 emu/g. The BET specific surface area of NH 2 -Fe 3 O 4 @NCS-COOH was 45.18 m2/g. The synthesized nanostructure was found to be stable in different ranges of pH due to covalent bonds between nanochitosan and Fe 3 O 4. [ABSTRACT FROM AUTHOR]

Flexible displays are a systematic revolution in the field of display, in which high-performance and high-barrier polymer substrates are considered to be one of the most important key materials. In this work, high water vapor barrier polyimides containing amide moieties were synthesized via the ternary polymerization of 4,4'-diaminobenzailide (DABA), 4,4'-diaminodipheny ether (ODA), and 3,3',4,4'-biphenyl-tetracarboxylic acid dianhydride (BPDA) followed by thermal imidization. The relationship between the content of amide moieties and the water vapor barrier property of the prepared polyimides was studied by means of density test, water absorbing test, water contact angle test, water vapor permeation test, fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), thermogravimetry coupled with fourier transform infrared spectrometry (TG-FTIR), wide-angle X-ray diffraction analysis (WXRD), mechanical performance test, etc. The results show that the introduction of amide groups into polyimide (PI) main chains can improve the water vapor barrier properties of the polyimides effectively. The water vapor transmission rate (WVTR) of the polyimide films can be improved from 8.2365 g.(m2.24 h)-1 to 0.8670 g.(m2.24 h)-1 with the increasing content of amide moieties. [ABSTRACT FROM AUTHOR]

Flexible displays are a systematic revolution in the field of display, in which high-performance and high-barrier polymer substrates are considered to be one of the most important key materials. In this work, high water vapor barrier polyimides containing amide moieties were synthesized via the ternary polymerization of 4,4'-diaminobenzailide (DABA), 4,4'-diaminodipheny ether (ODA), and 3,3',4,4'-biphenyl-tetracarboxylic acid dianhydride (BPDA) followed by thermal imidization. The relationship between the content of amide moieties and the water vapor barrier property of the prepared polyimides was studied by means of density test, water absorbing test, water contact angle test, water vapor permeation test, fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), thermogravimetry coupled with fourier transform infrared spectrometry (TG-FTIR), wide-angle X-ray diffraction analysis (WXRD), mechanical performance test, etc. The results show that the introduction of amide groups into polyimide (PI) main chains can improve the water vapor barrier properties of the polyimides effectively. The water vapor transmission rate (WVTR) of the polyimide films can be improved from 8.2365 g·(m²·24 h) -1 to 0.8670 g·(m²·24 h) -1 with the increasing content of amide moieties., Competing Interests: The authors declare no conflict of interest.