A Computational Study of the Polymerization-Induced Phase Separation Phenomenon in Polymer Solutions under a Temperature Gradient

2003 ◽  
Vol 12 (6) ◽  
pp. 413-424 ◽  
Author(s):  
Kam-Wa D. Lee ◽  
Philip K. Chan ◽  
Xianshe Feng
Keyword(s):  
Phase Separation ◽  
Temperature Gradient ◽  
Polymer Solutions ◽  
Computational Study ◽  
Polymerization Induced Phase Separation

scholarly journals A computational study of surface-directed phase separation in polymer blends under temperature gradient

2021 ◽  
Author(s):  
Mohammad Tabatabaieyazdi
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Temperature Gradient ◽  
Long Range ◽  
Spinodal Decomposition ◽  
Surface Potential ◽  
Short Range ◽  
Computational Study ◽  
Polymeric Materials ◽  
Partial Wetting

To apprehend the real industrial behavior of polymeric materials phase separation phenomenon, the nonlinear Cahn-Hilliard theory incorporating the Flory-Huggins-de Gennes free energy theory was used to study the non-uniform thermal-induced phase separation phenomenon in a symmetric binary polymer blend in which surface(s) with short- and long-range attraction to one polymer component compete with temperature gradient effects. The numerical results indicate that an increase of diffusion coefficient value will increase the rate of phase separation in the bulk but will decrease the growth rate of the wetting layer on the surface regardless of the surface potential strength. Also, the morphology transition from complete to partial wetting of the surface with short range surface attraction is successfully demonstrated. However, no partial wetting is observed for the surface with long-range potential. For shallow quenches, first, a growth rate of t 0.5 is observed in the early stage of spinodal decomposition phase separation at the surface and then a decline in the growth rate to t 0.13 in the intermediate stage occurred. For short- and long-range surface potential, the growth rate value of t 0.33 obtained in the bulk. The morphology results of temperature gradient effect on surface directed spinodal decomposition in short-range, long- range and multiple-surface attraction cases have been presented for the first time. It is realized that regardless of surface potential magnitude, surface enrichment is increased by higher temperature gradient (deep quenches on the side with no surface attraction). The studied models would provide more in depth understanding of polymer blendiprocesses.

scholarly journals Long-Range Surface-Directed Polymerization-Induced Phase Separation: A Computational Study

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 256
Author(s):  
Shima Ghaffari ◽  
Philip K. Chan ◽  
Mehrab Mehrvar
Keyword(s):  
Phase Separation ◽  
Long Range ◽  
Spinodal Decomposition ◽  
Surface Potential ◽  
Computational Study ◽  
Polymer Mixture ◽  
Condensation Polymerization ◽  
Wetting Layer ◽  
Polymerization Induced Phase Separation ◽  
Directed Polymerization

The presence of a surface preferably attracting one component of a polymer mixture by the long-range van der Waals surface potential while the mixture undergoes phase separation by spinodal decomposition is called long-range surface-directed spinodal decomposition (SDSD). The morphology achieved under SDSD is an enrichment layer(s) close to the wall surface and a droplet-type structure in the bulk. In the current study of the long-range surface-directed polymerization-induced phase separation, the surface-directed spinodal decomposition of a monomer–solvent mixture undergoing self-condensation polymerization was theoretically simulated. The nonlinear Cahn–Hilliard and Flory–Huggins free energy theories were applied to investigate the phase separation phenomenon. The long-range surface potential led to the formation of a wetting layer on the surface. The thickness of the wetting layer was found proportional to time t*1/5 and surface potential parameter h11/5. A larger diffusion coefficient led to the formation of smaller droplets in the bulk and a thinner depletion layer, while it did not affect the thickness of the enrichment layer close to the wall. A temperature gradient imposed in the same direction of long-range surface potential led to the formation of a stripe morphology near the wall, while imposing it in the opposite direction of surface potential led to the formation of large particles at the high-temperature side, the opposite side of the interacting wall.

scholarly journals A computational study of surface-directed phase separation in polymer blends under temperature gradient

2021 ◽  
Author(s):  
Mohammad Tabatabaieyazdi
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Temperature Gradient ◽  
Long Range ◽  
Spinodal Decomposition ◽  
Surface Potential ◽  
Short Range ◽  
Computational Study ◽  
Polymeric Materials ◽  
Partial Wetting

To apprehend the real industrial behavior of polymeric materials phase separation phenomenon, the nonlinear Cahn-Hilliard theory incorporating the Flory-Huggins-de Gennes free energy theory was used to study the non-uniform thermal-induced phase separation phenomenon in a symmetric binary polymer blend in which surface(s) with short- and long-range attraction to one polymer component compete with temperature gradient effects. The numerical results indicate that an increase of diffusion coefficient value will increase the rate of phase separation in the bulk but will decrease the growth rate of the wetting layer on the surface regardless of the surface potential strength. Also, the morphology transition from complete to partial wetting of the surface with short range surface attraction is successfully demonstrated. However, no partial wetting is observed for the surface with long-range potential. For shallow quenches, first, a growth rate of t 0.5 is observed in the early stage of spinodal decomposition phase separation at the surface and then a decline in the growth rate to t 0.13 in the intermediate stage occurred. For short- and long-range surface potential, the growth rate value of t 0.33 obtained in the bulk. The morphology results of temperature gradient effect on surface directed spinodal decomposition in short-range, long- range and multiple-surface attraction cases have been presented for the first time. It is realized that regardless of surface potential magnitude, surface enrichment is increased by higher temperature gradient (deep quenches on the side with no surface attraction). The studied models would provide more in depth understanding of polymer blendiprocesses.

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