Corona swelling

Historically, surface treatments to improve adhesion of coatings to plastics consisted of mechanical abrasion, solvent wiping, solvent swell that was followed by acid or caustic etching, flame treatment, or corona surface treatment. Each of these treatments has limitations, thus providing a strong driving force for the development of alternative surface preparation methods. Many of the common methods mentioned are accompanied by safety and environmental risks, increased risk of part damage, and expensive pollution and disposal problems. 

The box-like cell model of a PE star can be considered as a generalization of a classical mean-field Flory approach, which was first suggested to describe the swelling of a polymer chain in a good solvent [90], The Flory approach estimates the equilibrium dimensions of a macromolecule, as a function of its parameters, by balancing the free energy of intramolecular (repulsive) interactions with the conformational entropy loss of a swollen chain. Within the box-like approximation, the star is characterized by the radius of its corona, R (end-to-end distanee of the arms), or by the average intramolecular concentration of its monomers ... 

It can be shown that the addition of trace amounts of Z-ions to the solution leads to a rapid substitution of monovalent counterion in the star corona by Z-ions. This is due to their stronger attraction to the oppositely charged PE star polymer. Since a smaller number of Z-ions is needed to ensure the electroneutrality of the star interior, an increase in (i.e., in relative amount of Z-ions in the bulk of the solution) leads to a rapid decrease in the osmotic pressure inside the corona and, consequently, to a de-swelling of the PE star. This effect, of replacing monovalent counterions by multivalent ones is most pronounced at low salt concentrations (in the osmotic regime), where ... 

Fritz et presented a rheological study of SPEB that was extended to much higher volume fractions. These workers synthesized the SPEB by grafting chains of poly(methacrylic acid) to polymeric core particles. Depending on the pH of the solution, a marked swelling of the corona was found, as... 

Hydrogenation of a triple bond of dehydrolinalool was carried out at ambient pressure in a glass batch isothermal reactor installed in a shaker and connected to a gasometric burette. In the case of micellar catalysts based on amphiphilic block copolymers, different solvents providing the better swelling of micelle corona and access of the substrates to catalytic sites were used. For PS-b-P4VP based catalyst, toluene was used, while for PEO-b-P2VP based catalyst, a mixture of 30 vol. % water and 70 vol. % of isopropyl alcohol (/-PiOH) was emploied. 

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