Barrier properties migration

Excipients can influence delivery from topical and transdermal medications. The propensity of the drug to migrate from the formulation to the application surface is affected by factors such as lipophilicity of the vehicle, drug solubility in the formulation, and effects of additives on the barrier properties of the skin or mucosal surface. 

Physical characteristics of a support, namely porosity and specific surface area, have long been understood to play a key role in stabilizing active components of the catalysts in dispersed state. Explicitly or implicitly, they reflect topological properties of the carbon surface, namely the nature and quantity of (1) traps (potential wells for atoms and metal particles), which behave as sites for nucleation and growth of metal crystallites and (2) hindrances (potential barriers) for migration of these atoms and particles [4,5]. An increase in the specific surface area and the micropore volume results, as a rule, in a decrease in the size of supported metal particles. Formal kinetic equations of sintering of supported catalysts always take into consideration these characteristics of a support [6]. 

Blown film with special barrier properties one layer limits oxygen migration through the film and another provides protection from UV radiation. 

Silver nanoparticles were incorporated into PIA-based films which were obtained by casting from a CF solution. To accelerate the release of silver, composites were prepared by adding pure or surfactant-modified cellulose nanoctystals. The TEM images showed that silver and cellulose particles were distributed homogenously, results which were confirmed by the improvement of barrier properties to o g gen and water. However, the migration from the films and the release of silver increased with the presence of cellulose, especially when cellulose was modified with a surfactant. A potential interaction between the surfactant and PLA that resulted in degradation of the polymeric matrix might be the cause of such an effect. This report did not include the antimicrobial activity analysis of the prepared films. ... 

Fortunati, E., Peltzer, M., Armentano, 1., Torre, L., Jimenez, A., Kenny, J. M. (2012). Effects of modified cellulose nanocrystals on the barrier and migration properties of PLA nano-biocom-posites. (2), 948-956. 

E. Fortunati, M. Peltzer, I. Armentano, A. Jimenez, and J.M. Kenny, Combined effects of cellulose nanocrystals and silver nanoparticles on the barrier and migration properties of PLA nano-biocomposites,/. FoodEng., 118,117-124, 2013. 

Intercalation of thermoplastic starch with clay nanocomposites has been shown to improve modulus strength, thermal resistance, and enhance hardness [98,99], while the migration of additives has been shown to be at the level acceptable for food contact [ 100]. Elasticity of the films was however reduced though barrier properties are reported to be improved, without major change in the crystallinity of the polymers [101]. 

Inorganic—Organic Polymers with Barrier Properties Against Water Vapor, Oxygen and Migrating Monomers... 

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