Details of the phase sepn. of the poly(N-vinylcaprolactam) (PVCL) homopolymers and block copolymers of PVCL and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) were studied in aq. buffer solns. Phase sepn. occurred at either one or two temps. depending on pH. The lower crit. soln. temp. of PVCL can be fine-tuned by varying the mol. wt. of the block, whereas the phase sepn. temp. of the PDMAEMA block is strongly dependent on pH. The enthalpies of the collapse of the PVCL homopolymer and PVCL-b-PDMAEMA block copolymers were measured and show that the blocks phase sep. independently upon heating. PVCL is known to bind amphiphilic cations, and correspondingly, according to light scattering, the block copolymers dissolve as single mols. but also form aggregates at room temp. At temps. above the cloud points of both blocks, only homogeneous large aggregates were obsd. Zeta potential measurements confirmed that, upon heating, PDMAEMA blocks turn out from the collapsed PVCL globule toward the aq. phase.
- Critical solution temperature (lower
- phase sepn. of aq. poly(2-dimethylaminoethyl methacrylate-block-N-vinylcaprolactams))
- Cloud point
- Hydrodynamic radius
- Phase separation
- Zeta potential (phase sepn. of aq. poly(2-dimethylaminoethyl methacrylate-block-N-vinylcaprolactams))