Electrostatic and Steric Stabilization of Colloidal Dispersions

Author(s):  
Tharwat Tadros
2003 ◽  
Vol 17 (15) ◽  
pp. 2791-2820 ◽  
Author(s):  
Jiunn-Ren Roan

The Edwards model for polymers with excluded-volume interaction has been used to study steric stabilization of colloidal dispersions since Dolan and Edwards' work in 1975. Following the standard picture of steric stabilization since 1950s, Dolan and Edwards solved the model by treating the surfaces of colloidal particles as plane surfaces. Consequently, their result was also consistent with the standard picture: Reduction of conformational entropy of the adsorbed homopolymers results in a purely repulsive force that stabilizes the colloidal dispersion. Recently the Edwards model was solved without treating the spherical particle surfaces as plane surfaces. It was found that, contrary to the standard picture, the conformational entropy indeed increases and the force between particles may be either purely attractive or attractive at large particle-particle separation, repulsive at intermediate separation, and again attractive at small separation. Thus, the standard picture of steric stabilization was challenged. This review summarizes this recent progress in the theory of steric stabilization of colloidal dispersions. Reconciliation between the standard picture and the recent result, and possible directions for further research are also discussed.


2003 ◽  
Vol 104 (1-3) ◽  
pp. 1-24 ◽  
Author(s):  
D. Exerowa ◽  
N.V. Churaev ◽  
T. Kolarov ◽  
N.E. Esipova ◽  
N. Panchev ◽  
...  

2018 ◽  
Vol 24 (21) ◽  
pp. 2362-2374 ◽  
Author(s):  
Hyerim Yang ◽  
Hyeongmin Kim ◽  
Sumin Jung ◽  
Hyeyeon Seo ◽  
Shofa Khoirun Nida ◽  
...  

Background: Nanocrystallization technologies have been widely studied in recent years, as the formulation of drug nanocrystals solves problems of poor drug solubility and bioavailability. However, drug nanocrystals in the size range of 1–1000 nm usually need to be accompanied by stabilizers, such as polymers or surfactants, to enhance their stability. Despite their simplicity, improved dissolution rate, and enhanced bioavailability, the limited stability of nanocrystal formulations has prevented further development. Objective: The most effective way to handle this instability is to use stabilizers. This paper reviews various factors to consider for the production of stable drug nanocrystals and provides suggestions to overcome the problems associated with instability, such as aggregation and Ostwald ripening. Through various examples of stabilizers acting via electrostatic and steric stabilization, this review highlights the scope of enhancing the stability of drug nanocrystals. Conclusion: Studies on stabilizers used in the production of drug nanocrystals are ongoing; various factors, such as the effect of zeta potential on the stability of drug nanosuspensions, have already been revealed. However, it is necessary to determine the most appropriate stabilizer experimentally based on the various mechanisms and factors have been reviewed since the possible interactions between each drug and stabilizer are diverse.


AIChE Journal ◽  
2013 ◽  
Vol 59 (12) ◽  
pp. 4567-4581 ◽  
Author(s):  
Miroslav Soos ◽  
Daniele L. Marchisio ◽  
Jan Sefcik

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