(336d) Prausnitizian Phase Equilibria in Soft-Contact-Lens Copolymer Hydrogels | AIChE

(336d) Prausnitizian Phase Equilibria in Soft-Contact-Lens Copolymer Hydrogels

Authors 

Radke, C. - Presenter, University of California-Berkeley
Prausnitz, J., University of California at Berkeley


Prausnitizian Phase Equilibria in Soft-Contact-Lens Copolymer Hydrogels

C.J. Radke1,2 and J.M. Prausnitz1

1 Chemical and Biomolecular Engineering Department, University of California, Berkeley, CA,    
   94720-1462

2 Vision Science Group, University of California, Berkeley, CA, 94720-2002

85th Birthday Celebration of J. M. Prausnitz

Thermodynamics and Transport Properties

AIChE  San Francisco, 2013

            Nearly 50 % of first-time SCL wearers drop out because of discomfort. Wear comfort increases with increasing lens water content making water saturation a critical variable. John pioneered the language to tackle such problems and continues to apply them toward solution of practical problems. We report studies with undergraduate students on the swelling of 2-hydroxyethyl methacrylate (HEMA)/methacrylic acid (MAA) hydrogels over the complete range of MAA content. Gel water content strongly increases near the pK of MAA. At low pH, water content is insensitive to the MAA/HEMA ratio, whereas at high pH, small amounts of MAA increase water saturation dramatically, but less so as MAA copolymer fraction increases. Application of multipolymer Flory-Huggins-Rehner theory proves inadequate as do Donnan electrostatics. We propose specific complexation of water with charged acid groups of MAA along with charge-dependent ion-binding of salt counterions. John’s appetitive for mentoring students through insightful research remains alive and well at Berkeley.