Facile Assembly of Large-Area 2D
Microgel Colloidal Crystals Using Charge-Reversible Substrates
Weng, JY (Weng, Junying)[ 1,2 ] ; Li, XY (Li, Xiaoyun)[ 1,2 ] ; Guan, Y (Guan, Ying)[ 1,2 ] ; Zhu, XX (Zhu, X. X.)[ 3 ] ; Zhang, YJ (Zhang, Yongjun)[ 1,2 ]
LANGMUIR, 2016, 32(48): 12876-12884
DOI: 10.1021/acs.langmuir.6b03359
WOS:000389557400036
Abstract:
2D colloidal crystals (CCs) have important applications;
however, the fabrication of large-area, high-quality 2D CCs is still far from
being trivial, and the fabrication of 2D microgel CCs is even harder. Here, we
have demonstrated that they can be facilely fabricated using charge-reversible
substrates. The charge-reversible substrates were prepared by modification with
amino groups. The amino groups were then protected by amidation with
2,2-dimethylsuccinic anhydride. At acidic pH, the surface charge of the
modified substrate will change from negative to positive as a result of the
hydrolysis of the amide bonds and the regeneration of the amino groups. 2D
microgel CCs can be simply fabricated by applying a concentrated microgel
dispersion on the modified substrate. The negatively charged surface of the
substrate allows the negatively charged microgel spheres, especially those
close to the substrate, to self-assemble into 3D CCs. With the gradual
hydrolysis of the amide bonds and the charge reversal of the substrate, the
first 111 plane of the 3D assembly is fixed in situ on the substrate. The
resulting 2D CC has a high degree of ordering because of the high quality of
the parent 3D microgel CC. Because large-area 3D microgel CCs can be facilely
fabricated, this method allows for the fabrication of 2D CCs of any size.
Nonplanar substrates can also be used. In addition, the interparticle distance
of the 2D array can be tuned by the concentration of the microgel dispersion.
Besides rigid substrates (such as glass slides, quartz slides, and silicon
wafers), flexible polymer films, including polyethylene terephthalate and
poly(vinyl chloride) films, were also successfully used as substrates for the
fabrication of 2D microgel CCs.
