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1、Chapter 7,Chain-Growth Condensation Polymerization,Characteristics of condensation polymerization,Condensation polymerization based on the reactions of functional groups of the monomers Monomers are consumed fast Polymers are formed only in high conversion Uncontrolled molecular weight Uncontrolled
2、molecular weight distribution,A-R-B A-(BA)n-B,Polymerization behavior,Condensation polymerization,Living polymerization,Principles of chain-growth condensation polymerization,The change of the substituent effect induced by bond formation of the monomer drives the reactivity of the polymer end group
3、to become higher than that of the monomer. 2. In condensation polymerization based on a coupling reaction with a transition metal catalyst, the catalyst is intramolecularly transferred to and activates the elongated polymer end group after the coupling reaction of the monomer with the polymer.,Chem.
4、 Rev. 109(11), 5595-5619 (2009).,Character of condensation polymerization,Change of substituent effect,Poly(phenylene sulfide),Poly(phenylene oxide),Polyester,The reaction satisfied the requirements for the chain growth condensation polymerization, but 8 polymerization proceeded with concomitant pre
5、cipitation of polymer,Polyamide,Initiator,Molecular weight and its distribution,Disadvantages: 1. Require unusual base, N-octyl-N-triethylsilylaniline, and CsF and 18-crown-6. 2. Monomer: phenyl ester is not common. 3. Purification: separation of the polymer from byproducts,N-octylaniline and phenol
6、 by HPLC.,Common monomer,Highly pure polyamide with a defined molecular weight and low polydispersity can be obtained after simple treatment ot the reaction mixture with aqueous NaOH solution followed by evaporation. Byproducts: methanol, ammonia, and heximethyldisiloxane,LiHMDS: (CH3)3Si2NLi Commer
7、cially availble base,-Conjugated Polymers: Polymerization by Catalyst transfer,Transfer of catalyst,Mechanism of polymerization,Four important points were clarified:1. The polymer end groups are uniform among molecules; one end group isBr and the other is H; 2. The propagating end group is a polymer-Ni-Br complex; 3. One Ni molecule forms one polymer chain; 4. The chain initiator is a dimer of 40a formed in situ.,dppp,
