| Summary: | 碩士 === 國立中央大學 === 化學工程研究所 === 83 === The investigation attempted to use PS (polystyrene) and S-H
(copolymer of styrene and 2-hydroxyethyl metha crylate )
as modified agent for ethylcellulose-walled microcapsules,
and the model core is theophylline. Ethylcellulose (EC)
composite microcapsules were prepared by non-solvent addition
phase sepa- ration method. The influences of the release
rate with diff- erent composition of PS/ EC or S-H/EC composite
microcapsules were discussed. From the cloud point experiment，
the surfaces of microcapsules were affected by the
characterization and coacer- vation time of co-wall materials.
For the PS/EC system , the re- lease rate of the drug from
microcapsules decreased with in- creasing addition or
molecular weight of PS. Besides for the S-H/EC syrtem, the
released rate of the drug from microcapsules decreased with
increasing HEMA concentration, because the hydro- xy groups of
HEMA increased the molecular intereaction of S-H copolymer-EC.
In addition, dissolation results showed that the release rate
of microcapsules could be prolonged by the addition of small
amount of PS and S-H co-wall materials(1/39). It was found that
the time of 50% drug released, T50 could increase to 1.6 times
and 3.4 times . Especially, in the lower molecular wei- ght of
PS and the higher HEMA concentration of S-H copylymer.
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