In situ photon transmission technique for monitoring formation of hydrogels in real-time at various water contents

Abstract

Abstract In situ photon transmission technique was used to monitor the free radical crosslinking copolymerization (FCC) of acrylamide (AAm) and N , N ′-methylenebis (acrylamide) (Bis) in real-time. Gelation experiments were performed in various water contents at various wavelengths. It was observed that transmitted photon intensity, I tr , decreased dramatically at a certain gelation time, which is attributed to the increase in scattered light intensity, I sc , during FCC. Increase in I sc was modeled using Rayleigh's equation where gelation time was found to be proportional to the volume of the microgels. The change in I sc is found to be inversely proportional to the thirth power of the wavelength, λ , for high water content samples at early times. However, low water content samples produce smaller and constant power of λ during FCC at all times. The sizes of microgel particles and phase-separated domains were estimated.