Photomodification of polymer surface by utilizing photoinitiated amino‐groups formation–effects of comonomers on the dyeing of irradiated polymer surface

Photomodifications of polymer surface are investigated from the viewpoint of dyeing of the irradiated polymer surface. For this purpose, several kinds of acryloyl acetophenone oxime (AAPO) copolymers are prepared. As the other monomer components, methyl methacrylate (MMA), styrene (St), 2,3-epoxypropyl methacrylate (EPMA), 2-hydroxyethyl methacrylate (HEMA), N-vinyl pyrroridone (NVP), and n-butyl methacrylate (BMA) are used. In the photolysis of acyloxyimino (AOI) groups in AAPO copolymers, alkylimino groups can be introduced very effectively, which can be easily transformed to ammonium groups by hydrolysis in an aqueous solution of HCI. The surface of AAPO copolymers becomes dyeable with an acid dye (Congo Red) by the irradiation followed by HCI treatment and the degree of dyeing of the surface depends on not only the contents of ammonium groups but also the physical properties of the other monomer components. Although the hydrophilic or polar monomer such as NVP, HEMA, and MMA are cooperative for dyeing, the hydrophobic monomer such as St decreases the function of ammonium groups for dyeing. Although the undecomposed AAPO components in AAPO–MMA do not affect the degree of dyeing up to 24.5 mol % of AAPO contents in AAPO–MMA copolymers, they show the inhibition effect for dyeing of AAPO(38.8)–MMA at an earlier stage in irradiation. Aromatic moieties in AAPO are thought to inhibit the dyeing.