Poly-2-cyclopopyl-2-oxazoline as New Thermoresponsive Polymer
-
Bloksma, Meta M.; Weber, Christine; Perevyazko, Igor; Kuse, Anette; Baumgärtel, Anja; Vollrath, Antje; Hoogenboom, Richard; Schubert, Ulrich S.
- Abstract:
- The synthesis and microwave-assisted living
cationic ring-opening polymerization of 2-cyclopropyl-2-oxazoline
is reported revealing the fastest polymerization for an
aliphatic substituted 2-oxazoline to date, which is ascribed to
the electron withdrawing effect of the cyclopropyl group. The
poly(2-cyclopropyl-2-oxazoline) (pCPropOx) represents an
alternative thermo-responsive poly(2-oxazoline) with a reversible
critical temperature close to body temperature. The cloud
point (CP) of the obtained pCPropOx in aqueous solution was evaluated in detail by turbidimetry, dynamic light scattering (DLS)
and viscosity measurements. pCPropOx is amorphous with a significantly higher glass transition temperature (Tg ∼ 80 C)
compared to the amorphous poly(2-n-propyl-2-oxazoline) (pnPropOx) (Tg∼ 40 C), while poly(2-isopropyl-2-oxazoline) piPropOx is
semicrystalline. In addition, a pCPropOx comb polymer was prepared by methacrylic acid end-capping of the living cationic species
followed by RAFT polymerization of the macromonomer. The polymer architecture does not influence the concentration dependence of
the CP, however, both the CP and Tg of the comb polymer are lower due to the increased number of hydrophobic end groups.
- Year:
- 2011
- Type of Publication:
- Article
- Journal:
- Macromolecules
- Volume:
- 44
- Pages:
- 4057 - 4064