Synthesis Of Hemicyanine Fluorescent Dyes And Application On Fabrics

Nowadays there are many reports about hemicyanine fluorescent dyes with D-π-A conjugate structure, mainly because they have a good planarity and excellent fluorescent performance. However, it is difficult for a majority of hemicyanine fluorescent dyes meeting the requirements of the textiles’ light fastness in the market. In this article, experiment contents and conclusions are as follows.1) Four hemicyanine fluorescent dyes were synthesized with D-π-A conjugate structure by two steps, they are respectively trans-4-[p-(N,N-Diethyl)- amino-styryl]-N-ethyl pyridinium bromide(DEASPBr)、trans-2-[p-(N,N-Diethyl)-amino- styryl]-N-ethyl quinolinium bromide(DEASQBr) 、 1,3,3-trimethyl-trans-2-[p-(N,N- Diethyl) –amino-styryl]-N-methyl indolinium chlorate(DEASICl) and trans-4-[p-(N,N-Diethyl)–amino-styryl]-N-propylamine pyridinium chlorate(DEASPCl-N).Their structures were confirmed by Fourier infrared spectrum(FTIR) 、 nuclear magnetic resonance(NMR) and thermal analysis(TG).2) Acrylic fabrics were dyed with four hemicyanine fluorescent dyes following dyeing procedure of cationic dyes. Then their dyeing and fluorescence properties on acrylic fabrics were verified. The adsorption of four hemicyanine fluorescent dyes onto acrylic fabric follows a Langmuir mechanism; As electronic absorption performance in nitrogen heterocyclic declines, dyeing rate slows gradually and final dyeing percentage has a downward trend; As electronic absorption performance of nitrogen heterocyclic in the structures improves, maximum reflectance and fluorescence intensity of the acrylic fabrics dyed decline gradually. In four hemicyanine fluorescent dyes, Nitrogen heterocyclic of DEASICl has weaker alkaline, electron cloud density is lower on the nitrogen heterocyclic, light fastness of acrylic fabric dyed by DEASICl is above grade 4;3) Silk and nylon were dyed by hemicyanine fluorescent dyes(DEASPCl-N) following the dyeing procedure of acid dyes. The best procedure of dyeing silk : neutral condition(p H=7),95℃,no neutral electrolyte,1% dye concentration; the best procedure of dyeing nylon: neutral condition, 85℃, no neutral electrolyte, 1% dye concentration.4) By grafting hemicyanine fluorescent dye trans-4-[p-(N, N-Dihydroxyethyl)-amino-styryl]-N-ethyl pyridinium bromide(DEASPBr-C2) to the main chain of the polyurethane, waterborne polyurethane WPU-C2 was synthesized and applied to Acrylic fabrics and cotton.Compared to fluorescent dye DEASPBr-C2 aqueous solution, ultraviolet absorption peek is red-shifted of WPU-C2, the fluorescence emission peek is blue-shifted; As the solvent polarity enhances, ultraviolet absorption peek of WPU-C2 is obviously blue-shifted, the fluorescence emission peek is red-shifted and fluorescence intensity decreases. Acrylic fabrics were dyed by WPU-C2 following conventional procedure of cationic dyes, the K/S value is low because its molecular weight is too large to diffuse into the fabrics interior.WPU-C2 was applied to cotton following padding dyeing procedure, while in the baking process, isocyanate and hydroxyl groups on cotton form covalent bonds which firmly adsorb on the surface of fabric, cotton padding has high reflectivity.