Characterization of the structures of poly(urea–urethane) microcapsules

A series of poly(urea–urethane) microcapsules containing phthalate derivatives as a core material were prepared by an interfacial polymerization process in order to investigate the structural formation mechanism. Scanning electron microscopy (SEM) analysis for the cross sections of microcapsules rev...

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Bibliographic Details
Published in:International journal of pharmaceutics 2002-08, Vol.242 (1), p.147-153
Main Authors: Matsunami, Yuki, Ichikawa, Kimio
Format: Article
Language:English
Subjects:
Algorithms
Biological and medical sciences
Capsules
Core/shell structure
Differential Thermal Analysis
Drug Compounding
General pharmacology
Glass transition temperature
Mass Spectrometry
Medical sciences
Membranes, Artificial
Microscopy, Electron, Scanning
Oils
Pharmaceutical technology. Pharmaceutical industry
Pharmacology. Drug treatments
Phthalic Acids - chemistry
Poly(urea–urethane)
Polyurethanes - chemistry
Solubility parameter
Swelling
Temperature
Thermodynamics
ToF-SIMS
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Summary:A series of poly(urea–urethane) microcapsules containing phthalate derivatives as a core material were prepared by an interfacial polymerization process in order to investigate the structural formation mechanism. Scanning electron microscopy (SEM) analysis for the cross sections of microcapsules revealed the systematic formations of porous structures followed by the formation of core/shell structures. Critical values of the core oil content for the formation of porous and core/shell structures were obtained from SEM results and the critical values were found to be proportional to the solubility parameters of core materials. Dynamic mechanical measurements indicated an amorphous structure of wall membrane and the glass transition temperature was found to decrease with increasing the core oil content suggesting a plasticizing effect. The surface amount of the core oils absorbed in the wall membrane was estimated using time of flight secondary ion spectroscopy analysis and found to increase with increasing the oil content before reaching constant. This tendency was interpreted in terms of the structural formation of the microcapsules. The results obtained in the present investigation were reasonably understood on the basis of swelling theory of wall membrane and the Flory–Huggins interaction parameters of the systems were discussed.
ISSN:0378-5173
1873-3476
DOI:10.1016/S0378-5173(02)00138-2