Polymer Chemistry: synthesis Flashcards
What are the two ways in which polymers can be synthesised?
- Step growth polymerisation
- Chain growth polymerisation
Examples of step growth
- polyaddition
- polycondensation
In which sort of polymerisation is an initiator required to start a reaction?
Chain growth
- step growth doesn’t need an initiator but often is catalysed
What are the three distinct stages in chain growth polymerisation?
Initiation
Propagation
Termination
What is step growth polymerisation?
successive reactions between mutually reactive functional groups
- single or double monomer approach
What is chain growth polymerisation?
mechanisms in which the polymer chain grows only by reaction between a monomer and a reactive end group at the growing end chain
3 key chain growth polymerisation mechanisms
- free radical
- anionic polymerisation
- ring opening polymerisation (ROP)
What are the two type of common monomers for chain growth polymerisation?
- vinyl monomers
- cyclic monomers
Vinyl Monomers
radical polymerisation and sometimes ionic polymerisation
Cyclic monomers
usually ionic polymerisation (driven by ring strain)
What does heterolytic scission result in?
formation of ions
What does homolytic scission result in?
formation of radicals
What are common methods of radical formation?
- homolysis of weak sigma bonds
- single electron transfer (reduction)
How can radicals be formed from other radicals?
- substitution (chain transfer)
- addition (initiation/ propagation)
- elimination
How can homolysis be achieved?
compounds containing weak peroxide (-O-O-) or azo (-N=N-) linkages
