Switch Effect, Water‐Like State, and New Interaction Mechanism of an H‐Bonded Polycation–Polyacrylamide System to Realize Instant Decolorization of Dyeing Wastewater

Abstract A switch for controlling hydrogen bonds is incorporated into a polymer‐based system of polyamine polycation and polyacrylamide, with an ultrahigh molecular weight of 18 million; a surprising process results whereby the apparent viscosity of the whole system suddenly plunges from 321 cps to below 6.5 cps, forming a new water‐like phase state (WLPS) of an H‐bonded polymer‐based system. When WLPS products are used as decolorant materials to purify dyeing wastewater, they can flow similar to water during mass transfer and be quickly dissolved, immediately interacting with the anionic dyes in water. This observation is the first of a sudden change in apparent viscosity and the formation of a water‐like state in a polymer‐based system. Moreover, due to the switch effect to control hydrogen bonds, WLPS decolorants can change from water‐like states to strong hydrogen bonding states after interacting with anionic dyes, thus increasing the attractive forces of formed flocs to realize the instantaneous and highly adaptable decolorization of dyeing wastewater. It only took 10 s for the WLPS decolorants to remove more than 95% of various dyes in dyeing wastewater. Subsequently, a series of new cohesive floc structure–forms are first discovered by a computer imaging optical microscope.