Abstract:

Objective Structural colors have received increasing attention in the textile industry. Colloidal microspheres are commonly adopted to prepare structural colors including organic and inorganic microspheres. Compared with inorganic microspheres, organic microspheres have better industrial application prospects. However, the poor thermal stability of organic microspheres restricts the practical application. Therefore, the cross-linked poly(styrene-divinylbenzene-glycidyl methacrylate) (P(St-DVB-GMA)) microspheres were synthesized aiming to improve the thermal stability of structural color fabrics. This study is expected to provide a basis for solving the problem of poor thermal stability of organic microspheres.
Methods The cross-linked P(St-DVB-GMA) microspheres were synthesized by emulsion polymerization using styrene (St), glycidyl methacrylate (GMA) and divinylbenzene (DVB), which were adopted to construct structural color on polyester fabrics using atomization deposition method. The chemical structure of P(St-DVB-GMA) microspheres was characterized, and the influence of different mass ratios of non-ionic/anionic surfactants on particle sizes and structural colors of P(St-DVB-GMA) microspheres was investigated. The thermal stability, washing color fastness and rubbing color fastness of the structural color fabrics were evaluated.
Results P(St-DVB-GMA) microspheres with three different particle diameters of 245, 332, and 398 nm were obtained by adjusting the mass ratio of nonionic surfactant CO897 to sodium dodecyl sulfate (SDS) (ratios of 4.3:1, 4.0:1, and 3.3:1) during the emulsion polymerization. These microspheres were assembled into amorphous photonic crystals with short range order and long range disorder on the polyester fabric surface via atomization deposition to obtain blue, purple, and green structural colors. These structural colors on fabrics did not change with the view angles from 30°to 90°, showing the non-iridescent structural color. The color of P(St-DVB-GMA) structural color fabrics was gradually lightened with the increase of temperature from 60 ℃ to 200 ℃. However, the color did not disappear completely at 200 ℃, and still a more obvious structural color on appeared on the fabric surface. The reflectance peak of P(St-DVB-GMA) structural color fabric did not change, but the reflectivity at peak decreased gradually with the increase of treatment temperature. The peak reflectivity of the structural color fabric treated at 200 ℃ was reduced by about 5%. The results showed that the P(St-DVB-GMA) structural color maintained good stability at 200 ℃. The reason about these may be because of the difference of the glass transition temperatures (T_g) between them. The T_g of P(St-DVB-GMA) significantly increased to 150 ℃ because of introduction of the crosslinking agent DVB. The reflectance curve of the structural color fabric after washing was basically the same as that before washing, but the reflectivity at peak decreased by about 0.27% compared with that before washing. The results showed that the P(St-DVB-GMA) microspheres structural color fabrics had excellent washing colorfastness. The color of the P(St-DVB-GMA) microspheres structural color fabrics did not obvious change after 1, 10, 30, 50 cycles of rubbing compared with that before rubbing, indicating excellent rubbing color fastness of the structural color fabrics.
Conclusion Crosslinked P(St-DVB-GMA) microspheres were prepared by introducing the DVB through the emulsion polymerization. Three types of P(St-DVB-GMA) microspheres with different particle sizes were prepared by changing the mass ratio of surfactant CO897 and SDS during the synthesis process, so as to obtain blue, purple and green structural colors on the polyester fabric. The thermal stability of P(St-DVB-GMA) structural color fabric was obviously improved, attributing to the increase of T_g of P(St-DVB-GMA) microspheres by introducing crosslinking agent DVB. The P(St-DVB-GMA) microspheres structural color fabrics demonstrated excellent washing and rubbing color fastness because of the presence of reactive epoxy group in P(St-DVB-GMA) microspheres. This study provides the research basis for solving the problem of poor thermal stability of organic microspheres structural color, and provides ideas for the preparation of heat-resistant structural color materials.

Key words: structural color, microsphere, thermal stability, polyester fabric