Direct dyes as molecular sensors to characterize cellulose substrates

Six dyes were selected based on their molecular structure to test their suitability as sensors to characterize the fine structure of cellulose substrates. Cotton, mercerized cotton and microcrystalline cellulose were chosen to represent a variety of pore structures typically encountered in practical applications. Internally available surface areas were calculated. It is postulated that roughly 25% of the Connolly surface areas (CSA) of the sensors Direct Blue 1, Direct Blue 14, Direct Blue 53, Direct Red 28, and Direct Red 2 and 30% of the CSA of Direct Yellow 4 are representative of the space required for the sensor to dock onto cellulose surfaces. Molecular weight of the dye probes does not serve as a good indicator of sensor size. Molecular structure is a critical factor to take into account when selecting a probe.