INTERFACIAL PHENOMENA

Presentasi berjudul: "INTERFACIAL PHENOMENA"— Transcript presentasi:

1 INTERFACIAL PHENOMENA
Kuncoro Foe

2 REFERENCES Martin, Physical Pharmacy
Remington’s Pharmaceutical Science Sprowl, Prescription Pharmacy Husa’s Dispensing of Medication Burlage, Physical Pharmacy

3 Interface The boundary between two or more phases (liquid-gas, liquid-liquid, liquid-solid, solid-gas, solid-solid) Liquid interfaces (liquid-gas, liquid-liquid, liquid-solid) Solid interfaces (solid-gas, solid-liquid) Interfacial tension () : dyne/cm (cgs)

4 Surface The boundary between other phases with gas phase
Surface: gas-solid or gas-liquid interface Every surface is interface Phases: solid, liquid, gas Solid-solid is less important in pharmaceutical science Surface tension () : dyne/cm (cgs)

5 Utilization in Pharmacy (1)
Drug adsorption in dosage form Incompatibilities (undesirable) Deodorant (desirable) Mechanism of therapeutic efficacy Antidotum Drug penetration through biological membrane, eg. anthelmintics

6 Utilization in Pharmacy (2)
Formulation: stability and effectiveness Liquid dosage form Homogeneous system (solution) Heterogeneous system (emulsion, suspension) Interfacial phenomena should be considered, since drug absorption until the site of action

7 Liquid Interfaces (1) A liquid drop suspended in air tends to form a spherical shape, since (a) cohesive force  adhesive force, (b) to attain the smallest surface area

8 Liquid Interfaces (2) Surface tension (s.t.): gaya pada permukaan untuk mempertahankan bentuknya Interfacial tension (i.t.): gaya per satuan panjang pada interface antara 2 fase zat cair yang saling tidak campur i.t. = 0, completely miscible liquid (no interfacial tension, no boundaries)

9 Liquid Interfaces (3) = tegangan permukaan
f b = bobot maksimum supaya film tidak pecah (force to break the film) 2 L = the length of the movable bar in contact with the film

10 Surface & Interfacial Tension
Surface Free Energy Surface & Interfacial Tension Pada umumnya untuk cairan, apabila suhu meningkat maka tension menurun karena energi kinetik molekul meningkat

11 Measurement Methods Du Nouy ring method/tensiometer
Capillary rise method Drop weight Bubble pressure Sessile drop Wilhelmy plate

12 Spreading Coefficient (1)
Koefisien penyebaran spreading liquid dan sublayer liquid, tergantung pada: Gaya kohesi Gaya adhesi Apabila minyak diteteskan di atas cairan: Sebagian minyak tetap dalam bentuk globul Sebagian minyak menyebar membentuk ‘film’ pada permukaannya

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15 Spreading Coefficent (2)
Contoh soal:  heksana = 18 dyne/cm,  air = 72,8 dyne/cm, LS = 50,8 dyne/cm Apa yang terjadi apabila heksana diteteskan pada air? Apa yang terjadi apabila air diteteskan pada heksana?

16 Thank You 16