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Polycarbonates: Interfacial Polymerizations

Polycarbonates: Interfacial Polymerizations. Commercially Important Brunelle, D. J. Am. Chem. Soc., 1990, pg. 2399. Brunelle, D., Macromolecules , 1991, pg. 3035. Step Growth Polymerization of Poly(bisphenol A carbonate). Traditional Routes. Interfacial Route. Advantages

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Polycarbonates: Interfacial Polymerizations

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  1. Polycarbonates:Interfacial Polymerizations • Commercially Important • Brunelle, D. J. Am. Chem. Soc., 1990, pg. 2399. • Brunelle, D., Macromolecules, 1991, pg. 3035.

  2. Step Growth Polymerization of Poly(bisphenol A carbonate)

  3. Traditional Routes Interfacial Route • Advantages • High Molecular Weight • Excellent Optical Clarity • and color • Disadvantages • Phosgene based • Uses H2O and CH2Cl2 Melt Condensation • Advantages • Solvent Free • Potentially Phosgene Free • Disadvantages • Colored Product • Intermediate Molecular Weight

  4. CO2 & Polymer Processing Swelling and Plasticization of a Polymer Melt Impact: Lower T processing

  5. Melt Phase Condensation Polymerization • Viscosity () increases with conversion • High  hinders mixing and removal of condensate, • causing slower reaction rates • Addition of supercritical CO2 as a plasticizing agent • decreases , increasing mobility • Supercritical CO2 extracts reaction byproducts, shifts • equilibrium, increases DP CO2 + byproduct outlet Swollen polymer melt CO2 inlet

  6. 0 psi 2000 psi 3000 psi 4000 psi 5000 psi Swelling Measurements • In a closed system, the polymer swelling correlates to CO2 mass uptake by the polymer • Swelling measurements allow for the determination of the diffusion coefficient of CO2 in the polymer

  7. Solvent-Induced (CO2) Crystallization of Polycarbonate Polycarbonate Pellets Crystallized with Supercritical CO2 Amorphous Polycarbonate Pellets

  8. Solid State Polymerization Synthesize amorphous prepolymer Crystallize the prepolymer with supercritical CO2 to eliminate the need for organic solvents Heat the semicrystalline prepolymer between Tg and Tm Flow sweep fluid past the surface of the polymer particle to remove condensation byproduct Investigate the use of supercritical CO2 as a sweep fluid Amorphous region Crystalline region

  9. Solid State Polymerization: Solvent Induced Crystallization Solvent induced crystallization presents a unique opportunity to study solid state polymerization PETPC -Thermally crystallizes -Does not readily thermally crystallize -Fixed level of crystallinity -Can control crystallinity -Uniform crystallinity -Can control morphology Solvent front

  10. Mw versus Time as a Function of Temperature: SSP of Polycarbonate Beads (3.6 mm) with N2 as the Sweep Fluid Variable Temperature Profile: Hours 0-2: 180 °C Hours 4-6: 230 °C Hours 2-4: 205 °C Hours 6-12: 240 °C N2 flow rate 2 mL/min Macromolecules,1999, 32, 3167.

  11. Role of Phenol Diffusion core intermediate shell Phenol must diffuse from the particle to increase polymer molecular weight. The sample was separated into three regions for analysis... -molecular weight -percent crystallinity -melting point (Tm) What is the role of…. -phenol diffusivity -tortuosity -end group mobility Segment Radius Core = 0.0 to 0.4 mm Inter = 0.4 to 1.4 mm Shell = 1.4 to 1.8 mm

  12. 1 [Condensate] —— Xn2 MW as a Function of Diameter? PC Beads=3.6 mm N2 Flow=2 mL/min Macromolecules,2000, 33, 40.

  13. Variable Temperature 180 ºC N2 flow rate 2 mL/min Mw versus Time for the SSP of PC Powder(20 um)Using N2 as the Sweep Fluid

  14. PDI versus Time for the SSP of PC Beads (d =3.6 mm) and PC powder (20 um) at a variable temperature program PDI of Bead PDI of Powder Significant molecular weight distribution broadening observed in larger polymer particles.

  15. Copolymers in Step Growth Polymerizations

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