Rheological properties HMHEC solutions

The rheological properties of all HMHEC polymers are profoundly affected by the hydrophobe molar substitution (MS) and the hydrophobe chain length. For any given hydrophobic moiety, there is a threshold hydrophobe MS below which there are no significant associative interactions. The most common phenomenological evidence for associative behavior is a dramatic increase in the solution viscosity of HMHEC polymers as a function of hydrophobe MS. The solution viscosity of HMHEC polymers continues to increase as a function of hydrophobe MS until the maximum limit of solubility is reached, as which point the HMHEC polymer becomes insoluble in water.33... 

Hydrophobically modified water-soluble polymers (HMWSPs) exhibit enhanced solution viscosity and unique rheological properties. These properties can be explained in terms of intermolecular associations via hydrophobes. This chapter describes the synthesis and solution properties of HMWSPs, Particularly discussed are the solution properties of hydrophobically modified hydroxyethytjcellulose (HMHEC) in aqueous and surfactant systems, HMHECs interact with surfactants and thus modify solution viscosities. The structure and the concentration of the surfactant dictate the solution behavior of HMHEC. The unique solution properties of HMHEC can be exploited to meet industrial demands for specific formulations or applications. 

A few years ago, Landoll (2-4) reported that grafting a small amount of long-chain alkyl hydrophobes onto a nonionic water-soluble polymer leads to associative thickening behavior (i.e., enhanced viscosity, surface activity, and unusual rheological properties). This chapter deals with the general methods of preparation and solution properties of hydrophobically modified nonionic WSPs. Particularly described are the solution properties of hydrophobically modified (hydroxyethyl)cellulose (HMHEC) in aqueous and surfactant systems. 

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