Zero-Order Controlled Release Kinetics

Kyle Douglas, James Farber, Steven Flynn, Janie Gu, Vivian Qin, Jenny Shih, Jake Silberg, Anita Wamakima

Through Polymer Matrices

Dr. David Cincotta, Jeremy Tang

Controlled Release

• Normally 1st or 2nd order

• 0th order rare but essential

• Goal: Use semipermeable membrane to keep rate of release constant

Background

• Began in late 1940’s & 1950’s• Applications:

–Agriculture–Zoology–Cosmetics–Medicine–Environment

Background

Uncontrolled ReleaseEffective LevelToxic LevelControlled Release

Time

Con

cent

ratio

n of

Sub

stan

ce

Membrane: Polymers

• Series of repeating monomers• Diverse properties:

– Intermolecular forces– Molecular shape– Crystallinity

• Use different properties to control releasehttp://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/polymers.htm

Solubility Parameters

• Predict solubility of different substances

• Hansen solubility parameter• Equation: Ra

2 = 4(δ D1 - δ D2) 2 + (δ P1 - δ P2) 2 + (δ H1 - δ H2) 2

Hypothesis

• Principle of “like likes like”• Closer solubility parameters faster

diffusion rate

Polymers Tested

• Polyethylene (C2H4)• Ethylene-Vinyl Acetate

(EVA) Copolymer– Vinyl Acetate

(CH3COOCH=CH2)•10%•12%

– Rest is ethylene (C2H4)

Substances Released

2-Pentanol Ethyl Acetate HexaneMolecular Formula

C5H12O C4H8O2 C6H14

Mass (g/mol) 88.148 88.105 86.18 Properties • Most polar

• BP: 119oC• Somewhat

polar• BP: 77oC

• Least polar• BP: 69oC

Apparatus

Schematic of the Apparatus

Data

0 50 100 150 200 250 30039.00

40.00

41.00

42.00

43.00

44.00

45.00

46.00

f(x) = − 0.0131996869084025 x + 45.4659702562982R² = 0.997931754651983

Release of Hexane through EVA 10% Film

Time (min)

Mas

s (g)

Rates of Evaporation

HexaneEthyl Acetate

2-Pentanol

0.0E+00

2.0E-03

4.0E-03

6.0E-03

8.0E-03

1.0E-02

1.2E-02

1.4E-02

PE

EVA 10%

EVA 12%

Substance

Rat

e (g

/s•m

2)

Poly

mer

Mem

bran

e

Conclusion

• Zero-order release was achieved using the mechanism

• Solubility parameters did not account for numerous other factors

Future Studies

• Mixtures of molecules (i.e. perfume)• Other properties of polymers

– Size– Explore solubility parameters in-depth

• Non-volatile substances – different apparatus

Acknowledgements

• Dr. David Cincotta, mentor• Jeremy Tang, assistant• Sig Sigamani of Celanese Corporation

and Stephen Takacs, providing polymers

• Dr. David Miyamoto, director• NJGSS and sponsors, opportunity