Figure 2: Hydrophobic phase separation drives sharp pH response of UPS copolymers.
From: Molecular basis of cooperativity in pH-triggered supramolecular self-assembly
(a) Structures of small molecular base dipropylaminoethanol (DPA), polymeric bases of PEI, PEO-b-PDMA and PEO-b-PDPA. (b) pH titration curves of DPA, PEI, PEO-b-PDMA and PEO-b-PDPA. (c) Plot of pH transition sharpness (ΔpH10–90%) as a function of octanol–water partition coefficient (LogP) of small molecular bases (NH4Cl, Chloroquine and DPA) or repeating unit (neutral monomer) of commonly used polybases (poly(ethyleneimine), polylysine, chitosan, polyhistidine) and PEO-b-PR block copolymers. (d) Change of hydrodynamic diameter of UPS nanoprobe PEO-b-PDPA along pH titration coordinate. Significant increase of size indicated the formation of micelles. (e) TEM images of PEO-b-PDPA before (protonation degree at 95%) and after (protonation degree at 85%) critical micelle protonation degree (CMPD=90%). Micelle formation (yellow arrows) was observed when protonation degree was below CMPD. Scale bars, 100 nm.
