Carbon Dioxide and Nitrogen-Modulated Shape Transformation of Chitosan-Based Composite Nanogels

Abstract

Chitosan/poly[N-(3-(dimethylamino)propyl)methacrylamide]/poly(acrylic acid) (CS/PDMAPMA/PAA) composite nanogels (CPACNGs) were fabricated in the solution of chitosan by surfactant-free emulsion polymerization. N-(3-(Dimethylamino)propyl)methacrylamide (DMAPMA) and acrylic acid (AA) were initiated by 2,2′-azobis-2-methyl-propanimidamide to graft from the backbone of chitosan. Nanogels were formed by noncovalent forces, including of hydrogen bonds, hydrophobic, and electrostatic interaction. Nanogels were characterized by transmission electron microscopy, scanning electron microscope dynamic light scattering, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer spectra, and 1H NMR. Spherical nanoparticles were observed in the latex system. Nanogels exhibited an excellent CO2 responsivity and CO2/N2 reversible response and switchability and had a faster response rate. The morphological shape transformation of nanogels was modulated by bubbling with CO2 and N2. The responsive mechanism was explored by determining the pH and electrical conductivity. In addition, nanogels were successfully emulsified by bubbling with CO2, and then a phase transition was achieved by bubbling with N2 in the organic solvent/water mixture.

Advances in metal–organic framework-based hydrogel materials: preparation, properties and applications

“…287,288 The free amino groups in chitosan were able to provide basic sites for CO 2 , and thus chitosan was considered as a potential CO 2 -responsive polymer. 289,290 As a classic report, Wang et al successfully synthesized ZIF-8/chitosan nanocomposites using a chitosan hydrogel as the research object. 291 The chitosan concentrations and the ammonium hydroxide solution varied in the preparation of ZIF-8/chitosan nanocomposites.…”

CO2-responsive gels

“…The same research group extended this work to the preparation of CO 2 -responsive shape memory hydrogels in the form of CS/PDMAPMAm/polyacrylic acid (PAA) composite microgels. 300 The microgels were prepared via a self-assembly surfactant-free emulsion polymerisation process involving the generation of free radicals on the amino groups of the CS using the initiator 2,2′-azobis-2-methylpropanimidamide (VA-044), followed by grafting of DMAPMAm and AA onto these groups. Finally, a physical crosslinking process took place based on noncovalent interactions between the polymer chains, forming a semi-interpenetrating polymer network (semi-IPN) [Scheme 9(a)].…”

The lamellar MOFs@polymer networks hybrids fabricated in reversed microemulsion for efficient CO2 capture

“…50 In the FT-IR spectrum of polymer networks (PNs), the characteristic peak (δ CON-H ) occurred at 1531 cm À1 , C N occurred at 1261 cm À1 , and the characteristic peaks occurred at 2800-3000 cm À1 for CH 2 and CH 3 . 51,52 For the FT-IR spectra of ZIF-8@PNs, compared with the ZIF-8r nanoparticles, the peak at 421 cm À1 was weakened which may be caused by the functional groups in PNs compete with 2MeIM to coordinate with Zn 2+ . 53 Additionally, compared with PNs, the adsorption of CON-H was shifted from 1531 to 1482 cm À1 .…”