Compression-Responsive Photonic Crystals Based on Fluorine-Containing Polymers

Abstract

Fluoropolymers represent a unique class of functional polymers due to their various interesting and important properties such as thermal stability, resistance toward chemicals, repellent behaviors, and their low refractive indices in comparison to other polymeric materials. Based on the latter optical property, fluoropolymers are particularly of interest for the preparation of photonic crystals for optical sensing application. Within the present study, photonic crystals were prepared based on core-interlayer-shell particles focusing on fluoropolymers. For particle assembly, the melt-shear organization technique was applied. The high order and refractive index contrast of the individual components of the colloidal crystal structure lead to remarkable reflection colors according to Bragg’s law of diffraction. Due to the special architecture of the particles, consisting of a soft core, a comparably hard interlayer, and again a soft shell, the resulting opal films were capable of changing their shape and domain sizes upon applied pressure, which was accompanied with a (reversible) change of the observed reflection colors as well. By the incorporation of adjustable amounts of UV cross-linking agents into the opal film and subsequent treatment with different UV irradiation times, stable and pressure-sensitive opal films were obtained. It is shown that the present strategy led to (i) pressure-sensitive opal films featuring reversibly switchable reflection colors and (ii) that opal films can be prepared, for which the written pattern—resulting from the compressed particles—could be fixed upon subsequent irradiation with UV light. The herein described novel fluoropolymer-containing photonic crystals, with their pressure-tunable reflection color, are promising candidates in the field of sensing devices and as potential candidates for anti-counterfeiting materials.

Cross-Linking Strategies for Fluorine-Containing Polymer Coatings for Durable Resistant Water- and Oil-Repellency

“…Molecular weight was measured by size exclusion chromatography (SEC) with PS standards and the corresponding molar mass distribution showed a molar mass of 50.7 kg/mol (M n ) with a polydispersity index, Đ, of 1.13 (see Figure S2 ). The thermal properties of P(FA- co -StMA) have been investigated by DSC and revealed a glass transition temperature at −34.9 °C corresponding to P(FA) as well as a melting peak at 38.1 °C caused by P(StMA) (see Figure S3 ) ( T g P(FA): −36.7 °C [ 28 ], T m P(StMA): 37.8 °C [ 32 , 59 ]).…”

“…Polymers with perfluorinated groups feature surface characteristics that are quite different from those of non-fluorinated materials. In addition to excellent chemical and thermal stability [ 27 ], they also show a low refractive index [ 28 ], non-adhesive properties [ 29 ], and a rather low surface energy [ 30 ]. In general, fluorine-containing polymers were designed for use in space missions precisely as a result of their exceptional properties, but they were able to revolutionize the market for functional textiles at an early stage.…”

Progress in Stability Adjustment of Photonic Crystal Coatings on Fabrics or Fiber: A Review

“…Introducing colloidal particles or polymers with a low T g can improve the flexibility of PC coatings, 96 for example, using ''soft sphere'' 97 colloidal particles to produce structuring chromogenic fabric. A ''soft sphere'' is a sphere whose T g is lower than the usual temperature of PCs.…”

Mechanochromism of Structural‐Colored Materials

“…Among these adjustable parameters, mechanochromism was mainly achieved by changing the interplanar spacing ( d ), which can be easily altered via the tuning the intersphere spacing, [ 10,39,42 ] as well as the deformation of elastic nanospheres. [ 48–51 ]…”