Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Polymer-colloid-solvent mixtures phase separations

Stability in mixtures of colloidal particles and polymer molecules, dispersed in a solvent, has been the subject of experimental and theoretical investigations for a long time and it has applications in diverse fields such as paint technology, wastewater treatment, emulsion polymerization, biology etc. It has now been well recognized that polymer molecules can be used to induce either stabilization or flocculation (phase separation) in colloidal dispersions. It is important to distinguish between polymers which are adsorbed on the particle surface and those that are free in solution because the two situations usually lead to qualitatively different effects. Stability imparted by adsorbed polymers is known as steric stabilization and the flocculation or phase separation caused by the free polymer is due... [Pg.213]

Similar materials could be obtained by an emulsification method [253]. Nematic liquid crystal is emulsified into an aqueous dispersion of a water-insoluble polymer colloid (i.e., latex paint). An emulsion is formed which contains a droplet with a diameter of a few microns. This paint emulsion is then coated onto a conductive substrate and allowed to dry. The polymer film forms around the nematic droplets. To prepare an electrooptical cell a second electrode is laminated to the PDLC film [253]. In the phase separation and solvent-casting methods the chloroform solutions of liquid crystal and polymer are also used [254, 255]. The solution is mixed with the glass spheres of the required diameter to maintain the desired gap thickness and pipetted onto a hot (140 °C) ITO-coated glass substrate [255]. After the chloroform has completely evaporated another ITO-coated glass cover is pressed onto the mixture and then it is cooled down. Structural characteristics of the PDLC films are controlled by the type of liquid crystal and polymer used, the concentration of solution, the casting solvent, the rate of solvent evaporation, perparation temperature, etc. [254]. [Pg.215]

The possibility of entropy-driven phase separation in purely hard-core fluids has been of considerable recent interest experimentally, theoretically, and via computer simulations. Systems studied include binary mixtures of spheres (or colloids) of different diameters, mixtures of large colloidal spheres and flexible polymers, mixtures of colloidal spheres and rods," and a polymer/small molecule solvent mixture under infinite dilution conditions (here an athermal conformational coil-to-globule transition can occur)." For the latter three problems, PRISM theory could be applied, but to the best of our knowledge has not. The first problem is an old one solved analytically using PY integral equation theory by Lebowitz and Rowlinson." No liquid-liquid phase separation... [Pg.49]

A second method to manipulate the percolation of the CNTs in the polymer is controlled phase separation of the latex particles and CNTs. This was induced by slowly removing the continuous phase from the initial colloidal mixture. The combination of a soft latex and slow solvent removal led to the lowest percolation threshold [largest reduction]. Only negligible differences were observed for different solvent removal procedures for hard latexes. Of course, it should always be remembered that a direct comparison of two matrix materials with different structures is not completely accurate, as the interactions between the CNTs and the matrix could play a large role in determining the final percolation network. [Pg.134]


See other pages where Polymer-colloid-solvent mixtures phase separations is mentioned: [Pg.7]    [Pg.144]    [Pg.728]    [Pg.360]    [Pg.270]    [Pg.271]    [Pg.157]    [Pg.559]    [Pg.20]    [Pg.6]    [Pg.82]    [Pg.364]    [Pg.82]    [Pg.233]   
See also in sourсe #XX -- [ Pg.211 , Pg.212 , Pg.213 ]




SEARCH



Colloid/polymer mixtures

Colloidal mixtures

Colloidal phase

Colloidal phase separation

Colloidal polymers

Colloidal separation

Colloids phase separation

Colloids, separation

Mixture colloidal mixtures

Mixture separating mixtures

Mixtures colloids

Mixtures separating

Mixtures, separation

Phase separation polymer-solvent

Phase separation, polymers

Polymer colloids

Polymer mixtures, phase separation

Polymer separations

Polymer separators

Polymer-solvent mixture

Solvent separate

Solvents mixtures

Solvents solvent mixtures

© 2024 chempedia.info