posted on 2016-09-22, 00:00authored byYujie Zhang, Jie Dong, Hanxue Sun, Bo Yu, Zhaoqi Zhu, Junping Zhang, Aiqin Wang
Organic
allochroic materials have wide potential applications in various fields
but have so far been limited because of their low stability and low
and slow switching reversibility. Because of the extraordinarily high
durability of Maya Blue and the superhydrophobic lotus leaves, the
new solvatochromic and self-cleaning coatings with intense blue color
are fabricated by the combination of polysiloxane-modified palygorskite
(PAL@POS) and crystal violet lactone (CVL) via solid-state grinding.
The coatings are characterized using scanning electron microscopy,
diffusive reflection UV–vis spectra, and other analytical techniques.
The hydrogen bonding of the hydroxyl groups of PAL@POS with the carboxylate
groups of CVL+ is the origin of the intense blue color.
The interruption of the hydrogen bonding by the vapor of solvents
results in rapid discoloration of the coating. On the other hand,
the evaporation of the solvents from the coating results in complete
recovery of the original color by restoring the hydrogen bonding between
PAL@POS and CVL+. The polarity, hydrogen bonding ability,
and volatility of the solvents determine the solvatochromic properties
of the coating. The PAL@POS/CVL coatings feature high reversibility
and rapid switching between the colored and colorless states induced
by the vapor of various solvents. Also, the coatings are superhydrophobic
with fine self-cleaning properties and high durability in different
environments. Moreover, the CVL content in the coating is controllable
and can be as high as 4.8 wt %.