Surfactant-free HEMA Crystal Colloidal Paint for Structural Color Contact Lens

隐形眼镜 水凝胶 无表面活性剂

Graphical Abstract

A new type of structural color paint was fabricated by dispersing poly(methyl methacrylate-hydroxyethyl methacrylate (PMH) 聚（甲基丙烯酸甲酯 - 甲基丙烯酸羟乙酯)nanoparticles in 2-hydroxyethyl methacrylate (HEMA) solvent without additional surfactants. The paints then were directly cast to structural color contact lens by UV polymerization in mold.

PMH

(a) The structure of PMH nanoparticles. (b) FESEM image of the 90 nm PMH nanoparticles, the inset is a magnified image. (c) Corresponding size distribution of the nanoparticles with average diameter.

(a) Schematic diagram of the preparation for the paint of HEMA colloidal photonic crystals. (b) Digital photographs of the paints of HEMA colloidal photonic crystals with blue, green and red color and (c) The corresponding films after photo-polymerization. (d) Reflection spectra of the paint of HEMA colloidal photonic crystals and the corresponding films after photo-polymerization.

contact lenses

(a-c) SEM image of cross-sections of blue, green and red contact lenses with 90 nm, 120nm and 150 nm PMH nanoparticles. The internal pictures are the corresponding cross-sections schematic diagrams of color contact lenses. (d) The integral cross-section of the lens.

preparation for structural color contact lenses

(a) Schematic diagram of the preparation for structural color contact lenses. (b-c) Digital photographs of the front and lateral view of the structural color contact lenses. (d) Reflection spectra and (e) transmission spectra of the three color contact lenses.

(a) The cytotoxicity of the color contact lenses: MTT assay of the attachment and proliferation viability. (b) IFM micrographs of 3T3 cells cultured onto TCP and Blue, Green, Red color contact lenses, respectively.

Experimental Section

Synthesis of PMH and PMMA nanoparticles

The PMH colloidal polymer nanoparticles were synthesized by emulsifier-free emulsion polymerization method in a boiling condition. At first, 0.04 g NaCl and 160 mL deionized water were added into a 500 mL three-mouth flask with stirring. After NaCl was completely dissolved, 5 mL MMA as a monomer, 0.4 mL HEMA as a stabilizer and 0.35 mL DVB as cross-linker were added into the solution. After the mixture was heated to 110℃ for 20 min, 5 mL APS solution was injected into the solution. Then the system was reflowed under the boiling state with stirring for 3 h. The PMH particles were washed by repeating centrifugation of 25 min and
sonication of 30 min for three times. At last, the colloidal particles were further cleaned by dialysis against deionized water followed by an ion-exchange resin. The pure PMMA particles were prepared by adding the same reagents with the synthesis of PMH nanoparticle expert for HEMA monomer.

Preparation of PMH-in-HEMA colloidal photonic crystal paint