• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.815-820
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• 2009

Binary nanoemulsions which are defined as the, oil-droplet suspensions in binary solution ($H_2O$/LiBr), are developed to enhance the heat and mass transfer performance of absorption refrigeration systems. In this study, a novel two-step method is proposed to prepare the stable oil-in-binary solution (O/S) emulsion. Polymer is used as a steric stabilizer to stabilize the oil-droplets in a strong electrolyte ($H_2O$/LiBr). It is found that the thermal conductivity of the binary nanoemulsion is inversely proportional to the emulsion size while the concentrations of oil and $H_2O$/LiBr are less dominant for the thermal conductivity of binary nanoemulsions.

• Polymer(Korea)
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• v.25 no.4
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• pp.460-467
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• 2001

Inverse suspension polymerization of acrylamide (AM) in cyclohexane was carried out to study the effects of concentrations of sorbitan ester (Span) stabilizers and 2,2'-azobis (2-methyl propionamidine) dihydrochloride (AIBA) initiator, amount of monomer, shaking speed, and polymerization temperature on the particle size of the resulting poly (acrylamide) (PAM) beads and their molecular weights. It was found that the particle diameter. in general, decreased with increasing concentration of stabilizer, shaking speed, and water content in the aqueous phase, and with decreasing concentration of initiator and polymerization temperature. The average molecular weight of the resulting PAM beads was also found to increase with increasing concentrations of monomer and stabilizer, and also with decreasing concentration of initiator, polymerization temperature, and water content in the aqueous phase. In this study, PAM beads ranging 2 ~ 50 ${\mu}$m in diameter, with 8000000 ~ 12000000 in the weight average molecular weight were successfully prepared in almost 100% conversion.

• Polymer(Korea)
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• v.29 no.5
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• pp.440-444
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• 2005

An increase in the surface area of drugs by reducing particle sizes from microns to nanometers has been known as an efficient method to improve the bioavailability of water-insoluble drugs. To prevent drug nanoparticles from aggregation during the processes of drug formulation, a limited number of pharmaceutical inactive ingredients such as hydroxypropyl cellulose has been employed as stabilizers or dispersants. In this study, copolymers of hydrophilic and hydrophobic amino acids were synthesized by the ring opening polymerization of their N-carboxyanhydride monomers and evaluated as novel candidates to stabilize the nanoparticles of a water insoluble drug, naproxen. Naproxen nanoparticles stabilized by synthesized amino acid copolymers were successfully prepared in the size of $200\~500nm$ in 60 min by a wet comminution process. Particle size analysis showed that the effective stabilization performance of copolymers required the hydrophobic moiety content to be higher than $10 mol\%$. However, the molecular weight and morphology of copolymers was not the critical parameters in determining the particle size reduction. Their particle size was found to be stable up to 14 days without significant aggregation.