1. Polymer Synthesis CHEM 421 Polycarbonates: Interfacial Polymerizations Commercially Important Commercially Important Brunelle, D. J. Am. Chem. Soc., 1990, pg. 2399. Brunelle, D., Macromolecules, 1991, pg. 3035.

2. Polymer Synthesis CHEM 421 Step Growth Polymerization of Poly(bisphenol A carbonate)

3. Polymer Synthesis CHEM 421 Advantages High Molecular Weight Excellent Optical Clarity and color Disadvantages Phosgene based Uses H 2 O and CH 2 Cl 2 Advantages Solvent Free Potentially Phosgene Free Disadvantages Colored Product Intermediate Molecular Weight Interfacial Route Melt Condensation Traditional Routes

4. Polymer Synthesis CHEM 421 Swelling and Plasticization of a Polymer Melt Impact: Lower T processing CO 2 & Polymer Processing

5. Polymer Synthesis CHEM 421 Melt Phase Condensation Polymerization Viscosity (  ) increases with conversion High  hinders mixing and removal of condensate, causing slower reaction rates Addition of supercritical CO 2 as a plasticizing agent decreases , increasing mobility Supercritical CO 2 extracts reaction byproducts, shifts equilibrium, increases DP CO 2 inlet CO 2 + byproduct outlet Swollen polymer melt

6. Polymer Synthesis CHEM 421 In a closed system, the polymer swelling correlates to CO 2 mass uptake by the polymer Swelling measurements allow for the determination of the diffusion coefficient of CO 2 in the polymer Swelling Measurements 0 psi2000 psi3000 psi4000 psi5000 psi

7. Polymer Synthesis CHEM 421

8. Polymer Synthesis CHEM 421 Solvent-Induced (CO 2 ) Crystallization of Polycarbonate Amorphous Polycarbonate Pellets Polycarbonate Pellets Crystallized with Supercritical CO 2

9. Polymer Synthesis CHEM 421 Solid State Polymerization Synthesize amorphous prepolymer Crystallize the prepolymer with supercritical CO 2 to eliminate the need for organic solvents Heat the semicrystalline prepolymer between T g and T m Flow sweep fluid past the surface of the polymer particle to remove condensation byproduct Investigate the use of supercritical CO 2 as a sweep fluid Amorphous region Crystalline region

10. Polymer Synthesis CHEM 421 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 Solid State Polymerization: Solvent Induced Crystallization Solvent front

11. Polymer Synthesis CHEM 421 M w versus Time as a Function of Temperature: SSP of Polycarbonate Beads (3.6 mm) with N 2 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 Macromolecules, 1999, 32, 3167. N 2 flow rate 2 mL/min

12. Polymer Synthesis CHEM 421 Role of Phenol Diffusion Segment Radius Core = 0.0 to 0.4 mm Inter = 0.4 to 1.4 mm Shell = 1.4 to 1.8 mm Phenol must diffuse from the particle to increase polymer molecular weight. core intermediate shell The sample was separated into three regions for analysis... -molecular weight -percent crystallinity -melting point (T m ) What is the role of…. -phenol diffusivity -tortuosity -end group mobility

13. Polymer Synthesis CHEM 421 Macromolecules, 2000, 33, 40. PC Beads=3.6 mm N 2 Flow=2 mL/min MW as a Function of Diameter? 1 Xn2Xn2 [Condensate] ——

14. Polymer Synthesis CHEM 421 M w versus Time for the SSP of PC Powder (20 um) Using N 2 as the Sweep Fluid 180 ºC Variable Temperature N 2 flow rate 2 mL/min

15. Polymer Synthesis CHEM 421 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.

16. Polymer Synthesis CHEM 421 Copolymers in Step Growth Polymerizations