No abstract

Soy protein isolate (SPI) protein/polymer composite hydrogels (PPCGs) are fabricated in a urea solution of SPI using acrylic acid as monomer, ammonium persulphate (APS) as initiator, and N,N‐methylenebisacrylamide (BIS) and glutaraldehyde (GA) as cross‐linking agents. The scanning electron microscope (SEM) results show that SPI/polyacrylic (PAA) composite hydrogels formed network structure. In particular, in the absence of cross‐linking agent (GA), the network structure of composite hydrogels is also formed by BIS cross‐linking chains of PAA and the hydrophobic interactions between peptides from SPI and chain of PAA. In addition, composite hydrogels have good water absorption and present excellent pH sensitivity. Composite hydrogels adsorb bovine serum albumin (BSA) with higher adsorption capacity. BSA is the control released in pH 7.4 buffers and the accumulative release ratio achieved is 90%. It will be expected that these protein/polymer composite hydrogels could be applied for drug sustained release materials.

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.

Carbon dioxide (CO2)‐switchable composite nanogels are composed of biopolymer chitosan (CS) and synthetic polymer poly [N‐(3‐(dimethylamino) propyl) methacrylamide] (PDMAPMA). CS/PDMAPMA composite nanogels (CPCNGs) are fabricated in the solution of chitosan by soap‐free emulsion polymerization using N‐(3‐[dimethylamino] propyl) methacrylamide (DMAPMA) as the monomer and N,N‐methylenebis (acrylamide) (BIS) as the cross‐linker. The scanning electron microscope (SEM) results indicate that the nanogels are spherical nanoparticles with a diameter of about 50 nm. After purging with CO2, the original creamy‐white latex becomes a clear solution. While purging with N2, the clear solution is returned to the original latex state. Introduction of chitosan in nanogels remarkably enhances their CO2 sensitivity. In additional, the SEM results also suggest that phase transition behavior occurs through CO2 and N2 bubbling. The initial state of nanogels can be easily recovered by “washing off” the trigger gas with N2.

No abstract