GELS AND BRANCHED POLYMERS

Gels are network polymers swollen either in a solvent or in a randomly branched polymer. We have recently developed scaling theories for the modulus and equilibrium swelling of gels for three cases: polyelectrolyte gels, uncharged gels, and uncharged gels near their gel point.

Current work includes extending these models to polyampholyte gels. Polyampholytes are charged polymers with both (+) and (-) charges, and they are thus good models for protein gels such as gelatin.

PUBLICATIONS

  1. M. Rubinstein, R.H. Colby and J.R. Gillmor "Dynamic Scaling for Polymer Gelation" in Space-Time Reorganization in Macromolecular Fluids (F. Tanaka, T. Ohta and M. Doi, eds.) Springer Verlag, Berlin (1989); p. 66.
     
  2. L. Leibler, M. Rubinstein and R.H. Colby "Dynamics of Reversible Networks", Macromolecules, 24, 4701 (1991).
     
  3. S.K. Patel, S. Malone, C. Cohen, J.R. Gillmor and R.H. Colby "Elastic Modulus and Equilibrium Swelling of Poly(dimethyl siloxane) Networks", Macromolecules, 25, 5241 (1992).
     
  4. R.H.Colby, M. Rubinstein, J.R. Gillmor and T.H. Mourey "Scaling Properties of Branched Polyesters 2. Static Scaling above the Gel Point", Macromolecules, 25, 7180 (1992).
     
  5. T.A. Witten, M. Rubinstein and R.H. Colby "Reinforcement of Rubber by Fractal Aggregates", J. Phys. II France, 3, 367 (1993).
     
  6. R.H. Colby, J.R. Gillmor and M. Rubinstein "Dynamics of Near-Critical Polymer Gels", Phys. Rev. E, 48, 3712 (1993).
     
  7. M. Rubinstein and R.H. Colby "Elastic Modulus and Equilibrium Swelling of Near Critical Gels", Macromolecules, 27, 3184 (1994).
     
  8. S.P. Obukhov, M. Rubinstein and R.H. Colby "Network Modulus and Superelasticity", Macromolecules, 27, 3191 (1994).
     
  9. C.P. Lusignan, T.H. Mourey, J.C. Wilson and R.H. Colby "Viscoelasticity of Randomly Branched Polymers in the Critical Percolation Class", Phys. Rev. E, 52, 6271 (1995).
     
  10. M. Rubinstein, R.H. Colby, A.V. Dobrynin and J.F. Joanny "Elastic Modulus and Equilibrium Swelling of Polyelectrolyte Gels", Macromolecules, 29, 398 (1996).
      
  11. R.H. Colby "Modulus and Swelling of Polymer Gels," in Proceedings of the XIIth International Congress on Rheology (A. Ait-Kadi, J.M. Dealy, D.F. James and M.C. Williams, editors) Canadian Rheology Group (Quebec City, 1996), p. 255.
     
  12. C.P. Lusignan and R.H. Colby "Influence of the Chain Length between Branch Points on Gelation," in Proceedings of the XIIth International Congress on Rheology (A. Ait-Kadi, J.M. Dealy, D.F. James and M.C. Williams, editors) Canadian Rheology Group (Quebec City, 1996), p. 256.
     
  13. C.P. Lusignan, T.H. Mourey, J.C. Wilson and R.H. Colby, "Viscoelasticity of Randomly Branched Polymers in the Vulcanization Class", Phys. Rev. E., 60, 5657 (1999).
      
  14. J.R. Gillmor, R.W. Connelly, R.H. Colby and J.S. Tan, "Effect of Sodium Polystyrene Sulfonate on Thermoreversible Gelation of Gelatin", J. Polym. Sci. Pt. B: Polym. Phys,37, 2287 (1999).
     
  15. J. Janzen and R. H. Colby, "Diagnosing Long Chain Branching in Polyethylenes", J. Mol. Struct., 485, 569 (1999).
     
  16. R.H. Colby, C.P. Lusignan and J. Janzen, "Rheology of Randomly Branched Polymers", ANTEC 2000, 1, 1106 (2000).
     
  17. Y. Zhang, S. Ge, M. H. Rafailovich, J. C. Sokolov and R. H. Colby, "Surface Characterization of Cross-linked Elastomers by Shear Modulation Force Spectroscopy" Polymer 44, 3327 (2003).


  18. Rheology with Electrospun Fiber Formation of Linear and Branched Polyesters" Macromolecules 37, 1760 (2004).


  19. R. Bandyopadhyay, D. Liang, R. H. Colby, J. L. Harden and R. L. Leheny, "Enhanced Elasticity and Soft Glassy Rheology of a Smectic in a Random Porous Environment" Phys. Rev. Lett. 94, 107801 (2005).
     
  20. R. Patil, R.H. Colby, D.J. Read, G. Chen, Z. Guan, "Rheology of polyethylenes with novel branching topology synthesized by a chain-walking catalyst" Macromolecules
    21. 38, 10571 (2005)