Gel-forming macromers including at least four polymeric blocks, at least two of which are hydrophobic and at least one of which is hydrophilic, and including a crosslinkable group are provided. A composition of matter for chemically modifying a nonwoven textile article to achieve pilling resistance, soil release, strength, and abrasion resistance is also provided. Since the benzoxazole derivative represented by the general formula has an electron-injecting property, the benzoxazole derivative can be suitably used for light-emitting elements, light-emitting devices, and electronic devices. The clamps can be retained in their fully opened position without manual assistance.