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高分子化學 Polymer Chemistry

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高分子化學 Polymer Chemistry Powered By Docstoc
					                   Top 10 List
         Polymer products change our life
                   significantly
1.    Ties (Synthetic rubber)
2.    Non-sticky pan (Teflon)
3.    Polyethylene
4.    Stocking (Nylon)
5.    Polystyrene
6.    PVF
7.    PMMA
8.    Silicone
9.    Rayon
10.   Piping (PVC)

We will review this list in the end of this course
Synthesis
  Classification of Polymerization
• Carothers method / Reaction stoichiometric classification
   – Condensation vs addition polymerization
   – Determined by loss of weight (or not) on polymerization
   – Condensation:
      • mass of final polymer < mass of monomers
      • Small molecules lost (eg H2O or HCl) during polymerization
   – Addition:
      • Mass unchanged
      • Typically have higher MW and narrower MW distributions
   – This method is not sufficient.
   – Examples:
 Type of Condensation Reactions
• Elimination of H2O
  – Di-carboxylic acid + di-hydroxyl
  – Di-amino + Di-carboxylic acid
  – Di-functional monomer
• Transestification –carboxylic acid ester +
  alcohol
• Cyclization-type such as polyimide
See page 30 – Allcock book
High-performance polymers prepared by
           polycondensation
• Polycarbonate
• Polyethersulphone
• Polyetheretherketone
• Poly(p-phenylene terephthalamide)
• Polyimide
Main applications, Tg and modulus
          Examples – condensation
                            )
•    Polyester
•    Polycarbonate
•    Polyethersulphone
•    Polyetheretherketone
•    Poly(p-phenylene terephthalamide)
•    Polyamide
•    Polyimide
•    Polyanhydrides
•    Polybenzimidazoles
•    PPQ polyquinoxalines
    Homework: Main applications, Tg and modulus, issues
                   PET
• Transestification rxn – low solubility and
  high Tm of terephthalic (sublimes at 573K)
Polyamide (nylon)
               Polyaddition
• Polyurethanes (RA2 + RB2)
  – Diisocyanates with diols
• Polyureas (RA2 + RB2)
  – Diisocyanates with diamine
Classification of Polymerization
 Classification of Polymerization
• Mechanistic classification:
     – Step-growth (step reaction) vs Chain-growth (chain-reaction)

Step Polymerization                                Chain Polymerization
Any two molecular species can react                Growth occurs only by addition of monomer to
                                                   active chain end.

Monomer disappears early                           Monomer is present throughout, but its
                                                   concentration decreases.

Polymer MW rises throughout.                       Polymer begins to form immediately.

Growth of chains is usually slow (minutes to       Chain growth is rapid (second to microseconds).
days).
Long reaction times increase MW, but yield of      MW and yield depend on mechanism details.
polymer hardly changes.


All molecular species are present throughout.      Only monomer and polymer are present during
                                                   reaction.

Usually (but not always) polymer repeat unit has   Usually (but not always) polymer repeat unit has
fewer atoms than had the monomer.                  the same atoms as had the monomer

				
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posted:5/12/2014
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