10. Branched and crosslinked polymers Flashcards
What are dendritic polymers?
Dendritic polymers are highly branched polymers with controllable structures, which possess a large population of terminal functional groups, low solution or melt viscosity, and good solubility. Their size, degree of branching and functionality can be adjusted and controlled through the synthetic procedures.
What is a supramolecule assembly?
A supramolecular assembly or “supermolecule” is a well defined complex of molecules held together by noncovalent bonds.
What is the difference between convergent and divergent construction of dendrimers?
In divergent construction the dendrimer is assembled from the core and out, in convergent small pieces are assembled first and then gathered around a focal point.
What is the difference between hyperbranched polymers and dendritic polymers?
Hyperbranched polymers have a more random structure than dendritic.
Why do polysiloxanes have a low Tg?
Due to higher flexibility in the backbone because of larger bond angles and bond lenghts.
What is the main structural difference between Novolacs and Resoles?
Novolacs do not contain hydroxymethyl groups.
What is an alkyd?
A polyester modified with oils (fatty acids)
What is a dendromer?
One branch of a dendrimer.
Through which synthetic approach would you expect most defects in the dendrimer structure?
(divergent, convergent or one pot)
Divergent
Which preparation process requires the most material for preparation of a third generation dendrimer?
(divergent, convergent or one pot)
Convergent
Which class of dendrimers are most difficult to prepare with a functional surface? (PAMAM, Frechet or Bis-MAP)
Frechet, because it is convergent which means the funtional groups would have to be well protected through every generation step.
What is the majority of the thermoset systems based on?
Formaldehyde resins
Phenol, urea, melamine
What are polyarylates?
Polyesters from phenolic monomers
