Polymer Synthesis CHEM Polycarbonates

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Polymer Synthesis CHEM Polycarbonates Powered By Docstoc
					    Polycarbonates:                   Polymer Synthesis
  Interfacial Polymerizations             CHEM 421




• Commercially Important
Brunelle, D. J. Am. Chem. Soc., 1990, pg. 2399.
Brunelle, D., Macromolecules, 1991, pg. 3035.
Step Growth Polymerization of                                                         Polymer Synthesis
 Poly(bisphenol A carbonate)                                                              CHEM 421



       n   HO                         OH                    Polycarbonate
                                                 o
                                                             Oligomers
                                           181-300 C
                                                                 +
                         +

                     O                      LiOH
       n           O C O
                                                       (2n-1)               OH



                             Polycarbonate Oligomers

             O                                O
           O C O                            O C O                                OH
                                                       m



                                    O
      HO                          O C O                                     OH
                                            m


                     O                                    O
                   O C       O                          O C O
                                                                       m
      Traditional Routes                                                                  Polymer Synthesis
                                                                                              CHEM 421

         Interfacial                                                    Advantages
         Route                                                          •High Molecular Weight
                                                                        •Excellent Optical Clarity
                                                    Phase
             
                                            O-
                 O                               + Transfer + H2O
                                                   Catalyst              and color
                                                                        Disadvantages
                          O                                             •Phosgene based
                                   +        CH2Cl2
                     Cl   C   Cl                                        •Uses H2O and CH2Cl2
                                                           O

                                                 ( O       C        O                )n



     Melt Condensation
                                                                        Advantages
HO                                     OH
                                                                        •Solvent Free
                     +
                                                                        •Potentially Phosgene Free
                                                                        Disadvantages
                     O

         O           C    O
                                                                        •Colored Product
                                                                        •Intermediate Molecular Weight
CO2 & Polymer Processing                     Polymer Synthesis
                                                 CHEM 421




  Swelling and Plasticization of a Polymer Melt


                                               Impact:
                                              Lower T
                                             processing
           Melt Phase Condensation
                                                               Polymer Synthesis
                Polymerization                                     CHEM 421



• 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
  CO2 inlet
                                                                 melt
    Swelling Measurements                      Polymer Synthesis
                                                   CHEM 421




 0 psi     2000 psi   3000 psi   4000 psi 5000 psi
• 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
                                                 Polymer Synthesis
                                                     CHEM 421


                       o r aM g l p
                       l bt = / ) o
                        y oe 5 m s
                        c    00  Ed
                       Pan(n, 0 oxe
                           cc
                          e i  a 0
                         Srt C 3
                        op i l O 5
                                t
                        t u ra 2 2 C

                   0
                   6



                   0
                   5
t-V 0)/V 0]x10%
                   0
                   4



                   0
                   3



                   0
                   2
PercntSweling[(V


                   0
                   1



                   0
                   0    0
                        0
                        10   0
                             0
                             20   3
                                  0
                                  00   0
                                       0
                                       40   0
                                            0
                                            50

                             ru i
                             e e )
                              s (
                              s p
                             P rs
     Solvent-Induced (CO2)
                                 Polymer Synthesis
 Crystallization of Polycarbonate    CHEM 421




Polycarbonate
    Pellets
                               Amorphous
 Crystallized
                              Polycarbonate
     with
                                  Pellets
 Supercritical
     CO2
 Solid State Polymerization                         Polymer Synthesis
                                                        CHEM 421


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
 Solid State Polymerization: Solvent Synthesis
                                   Polymer
                                       CHEM 421
       Induced Crystallization

Solvent induced crystallization presents a unique opportunity to study solid
state polymerization

                        PET                                       PC
 -Thermally crystallizes                   -Does not readily thermally
crystallize
 -Fixed level of crystallinity            -Can control crystallinity
 -Uniform crystallinity                   -Can control morphology




                                        Solvent front
            Mw versus Time as a Function of Temperature:
               SSP of Polycarbonate Beads (3.6 mm)                    Polymer Synthesis
                                                                          CHEM 421
                     with N2 as the Sweep Fluid
                                     Variable Temperature Profile:
            5
            2
            00
             0                           Hours 0-2: 180 °C         Hours 4-6: 230 °C
                                         Hours 2-4: 205 °C         Hours 6-12: 240 °C

            0
            2
            00
             0                        Vl Ter
                                       ri
                                       a e pu
                                          b m ,
                                        a er ea
                                              t
                                      ny0 o
                                       i l ,0 l
                                       ta 0/ m
                                      I i l5 g



            5
            0
            10
             0                         Vl Ter
                                        a e pu
                                        ri
                                         a er e
                                           b m :
                                               t
                                               a
                                       ny0 o
                                        i l ,0 l
                                        ta 5/ m
                                       I i l2 g
Mw(g/mol)


                                                      8
                                                      0
                                                      1C
            0
            0
            10
             0


                                                      6
                                                      0
                                                      1C
            0
            0
            50




              0
                0      2     4        6         8       0
                                                        1      2
                                                               1
                                 ie r
                                 m s
                                  Ho
                                 T( u)

                            Macromolecules, 1999, 32, 3167.      N2 flow rate 2 mL/min
Role of Phenol Diffusion                       Polymer Synthesis
                                                   CHEM 421


                         Phenol must diffuse from the
                         particle to increase polymer
                         molecular weight.
                         The sample was separated into
         core
                         three regions for analysis...
      intermediate              -molecular weight
                                -percent crystallinity
         shell                  -melting point (Tm)

                         What is the role of….
   Segment Radius
                               -phenol diffusivity
 Core = 0.0 to 0.4 mm
                               -tortuosity
 Inter = 0.4 to 1.4 mm
                               -end group mobility
 Shell = 1.4 to 1.8 mm
MW as a Function of Diameter?                                      Polymer Synthesis
                                                                       CHEM 421



              Ms T a F tn R l o o
              w
                r
               v ui e a n
               e s m    c
                     s ui o a P i
                         of di it
                             a s n
                                                                            1
            2 0
            00
             0                                           [Condensate]      ——
            1 0
            80
             0                                                             Xn2
                                                          HE
                                                          SLL
            60
             0
            1 0

            40
             0
            1 0

            20
             0
            1 0
                                                          NE
                                                          ITR
Mw(g/mol)



            00
             0
            1 0

            0
            80
             0
                                                          O
                                                          CE
                                                           R
            0
            60
             0

            0
            40
             0

            0
            20
             0

             0
              0   2   4        6      8       0
                                              1      2
                                                     1
                          i e u
                          m  Hr
                              s
                          T (o )

                                         = C
                                          1
                                         T8
                                         1 0
             O . t0 m
             R0 .
              E
            C 0o m 4
              R
             E4 .  4
            IT 0 o m
            N . t1 m                     T0
                                          2
                                         = C
                                         2 5
             H 1o m
             E 4 .
              L    8
            S L. t 1 m                   T3
                                         = C
                                          2
                                         3 0
                                         = C
                                          2
                                         T4
                                         4 0
                                                                 PC Beads=3.6 mm
                         Macromolecules, 2000, 33, 40.           N2 Flow=2 mL/min
Mw versus Time for the SSP of PC Powder                                     Polymer Synthesis
  (20 um) Using N2 as the Sweep Fluid                                           CHEM 421



                             40000


                             35000                                           Variable
                             30000
                                                                           Temperature
 M olecular W eight (M w )




                                                                         o
                                                                        1r
                                                                        =
                                                                        1
                                                                        8
                                                                        0
                                                                        Tr
                                                                         C
                                                                         fs
                                                                         oh
                                                                          o
                                                                          u
                                                                          2
                                                                               o
                             25000                                      Tr
                                                                        =
                                                                        2
                                                                        0
                                                                        5
                                                                        2r
                                                                         C
                                                                         fs
                                                                         o
                                                                         2h
                                                                          o
                                                                          u
                                                                               o
                                                                        3r
                                                                        =
                                                                        2
                                                                        3
                                                                        0
                                                                        Tr
                                                                         C
                                                                         fs
                                                                         o
                                                                         2o
                                                                          u
                                                                          h
                             20000                                       o
                                                                        Tu
                                                                        =r
                                                                        2s
                                                                        4
                                                                        0
                                                                        4r
                                                                         C
                                                                         f
                                                                         o8
                                                                          h
                                                                          o
                                                                          1

                             15000


                             10000


                              5000
                                                              180 ºC
                                     0   5    10        15   20

                                             Time (hours)


                                                                       N2 flow rate 2 mL/min
PDI versus Time for the SSP of PC Beads (d =3.6 mm) and
                                                                             Polymer Synthesis
  PC powder (20 um) at a variable temperature program                            CHEM 421




                                   2.6
 Polydispersity Index (M w /M n)




                                                                          PDI of Bead
                                   2.4


                                                                           o
                                                                          1r
                                                                          =
                                                                          1
                                                                          8
                                                                          0
                                                                          Tr
                                                                           C
                                                                           fs
                                                                           oh
                                                                            o
                                                                            u
                                                                            2
                                   2.2                                        o
                                                                          2r
                                                                          =
                                                                          2
                                                                          0
                                                                          5
                                                                          Tr
                                                                           C
                                                                           fs
                                                                           o
                                                                           2o
                                                                            u
                                                                            h
                                                                              o
                                                                          3r
                                                                          =
                                                                          2
                                                                          3
                                                                          0
                                                                          Tr
                                                                           C
                                                                           fs
                                                                           o
                                                                           2o
                                                                            u
                                                                            h
                                                                           o
                                                                          4r
                                                                          =r
                                                                          2s
                                                                          4
                                                                          0
                                                                          Tu
                                                                           C
                                                                           f
                                                                           o8
                                                                            h
                                                                            o
                                                                            1
                                   2.0




                                   1.8
                                                                          PDI of Powder
                                         0   5    10      15    20   25

                                                 Time (hours)

Significant molecular weight distribution broadening observed in larger polymer particles.
Copolymers in Step Growth   Polymer Synthesis
     Polymerizations            CHEM 421

				
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