A new method was proposed to prepare binary composite colloidal crystal hydrogels by interlocking the as-prepared polystyrene/sulfonated polystyrene core/shell colloidal crystal hydrogel with a second responsive gel.The shell thickness thus the core size were synchronously controlled by altering the sulfonation time and temperature.The proper monomers were radically polymerized forming the second gel within the first gel network.The composition and structure were confirmed.Nanopatterned hydrogel including porous bulk hydrogels and surface patterned hydrogels were derived by properly treating the binary composite hydrogels.Specially,some typical patterns such as arrays of “nano-bowls",arrays of “nano-ribbons" and “nano-mask" were achieved by changing the treatment method such as by immersion in the solvent,after solvent evaporation from the sample surface during high rate rotation.This work provides a method to prepare nanopatterned hydrogels.
Monodispersed polystyrene latexes (100～500 nm) were prepared using seed emulsion polymerization.Hard and ordered polystyrene colloidal crystals were obtained by ambient drying the monodispersed polystyrene dispersions.Polystyrene colloidal crystals were chemically modified by controlled sulfonation with sulfuric acid to derive a novel macro ordered hydrogels including ordered hydrogels and core/shell hydrogels,in which sulfuric acid and sulfone groups are responsible for the hydrophilic and crosslinking performances,respectively.The chemical structure and morphologies of the hydrogels were characterized by FT IR.It is shown that at a given concentration of sulfuric acid,the structural features of the samples are controlled by sulfonation time and temperature.The modification starts from the outer layer of polystyrene spheres of the colloidal crystals and increases both in reaction rate and sulfone group amount with temperature.A preliminary mechanism of the sulfonation process to prepare the ordered structures was proposed.
The monodisperse silica particles self-assembled colloidal crystals were used as templates to synthesize pH value and temperature responsive ordered macorporous hydrogels. The ordered structure arranged by the uniform pores and the pore-pore interconnectivity through the window channel is confirmed by SEM characterization. UV-Vis-near IR absorption experiment result reveals that the wavelength at the stop band peak is tunable within the whole visible spectrum via simply altering some parameters such as pH value and light incidence angle. This finding allows to design frequency-tunable photonic band gap materials.
Monodisperse core-shell (polystyrene/DAAM-EA-AM) emulsions were prepared by two-step seed polymerization,and crosslinked films were obtained by ambient drying the copolymerization emulsions accompanying a interfacial crosslinking between DAAM/ADDH.The crosslinking degree increased with thermal treatment temperature and time.After alkaline hydrolysis of ester and amide groups resulting carboxylic groups,the films were transformed to be mesostructured hydrogels.The chemical composition and ordered morphologies were experimentally confirmed by FT-IR,SEM and POM.Water uptake of the hydrogels decreased with the thermal treatment time of the films,implying the crosslinking degree also increased.
