“Schizophrenic” Micellization of Poly(Acrylic Acid)-B-Poly(2-Dimethylamino)Ethyl Methacrylate and Responsive Behavior of the Micelles

Aggregation Behavior of Asymmetric Diblock Polyampholyte in Aqueous Solution over a Wide Range of pH and Ionic Strength

“…Those authors proposed the existence of additional non-electrostatic interactions between the copolymers as a possible reason for this behavior, in order to compensate for the existing electrostatic repulsion between the remaining charged groups. Zhang et al, [12] Mao et al, [23] and Gohy et al [13] reported the presence of micelles with different sizes at low and high pH values for PDMAEMA-b-PAA, PDMAEMAb-PMAA, and PDEAEMA-b-PMAA asymmetrical copolymers in solution. According to those authors, at low pH, the acid units of the copolymer are neutral and somewhat hydrophobic while the PDMAEMA chains are protonated and positively charged.…”

“…Conversely, the more compact PDMAEMA cores were hardly affected by the addition of NaCl, and just slight changes in size were observed. [12,23] It is well known that carboxylic acid groups are able to form dimers by hydrogen bonding in aqueous solutions at low pH. [50,51] Besides that, non-ionized acrylic acid moieties can also form hydrogen bonds with protonated amine groups.…”

“…Other studies [11,12,23,24] have also reported on the solution behavior of annealed diblock polyampholytes as a function of copolymer composition, pH, temperature, and ionic strength. However, most of these publications focused on the polyampholyte behavior at extreme pH ranges, that is, at low and high pH, where one of the blocks of the polyampholyte is no longer charged and the occurrence of electrostatic complexation would not be expected.…”

Synthesis and pH-Responsive “Schizophrenic” Aggregation of a Linear-Dendron-Like Polyampholyte Based on Oppositely Charged Polypeptides

“…Much effort has been made to regulate the morphologies of “schizophrenic” aggregates. By introducing both thermo- and pH-sensitive segments into the same molecule, spherical micelles, vesicles and even short rod-like micelles have been obtained via cooperatively adjusting the temperature and the pH value of the aqueous solutions. − Here, we report the “schizophrenic” self-assemble behaviors of the polypeptide based nonlinear polyampholyte, for which the aggregates with various morphologies can be easily obtained by only regulating the pH values of the solutions. During the “schizophrenic” micellization process, the pH-responsive hydrophilic–hydrophobic transition of various polypeptide segments and the electrostatic interactions between the charged units are the driving force for forming and changing the structure of aggregates, whereas the steric effect derived from nonlinear molecular topology as well as rod–coil conformational transition of polypeptide segments have evident influences on the aggregate morphology.…”

Aqueous one-pot synthesis of well-defined zwitterionic diblock copolymers by RAFT polymerization: an efficient and environmentally-friendly route to a useful dispersant for aqueous pigments

“…In principle, controlled radical polymerization techniques such as ATRP, 24,25 nitroxide-mediated polymerization (NMP) 26,27 and reversible addition-fragmentation chain transfer (RAFT) polymerization 28,29 should enable the direct synthesis of zwitterionic diblock copolymers without requiring any protecting group chemistry. An early example of such an approach was reported by Gabaston et al, 30 who utilized NMP to prepare block copolymers of poly(sodium 4-styrenesulfonate) and poly(4-(dimethylamino)methylstyrene) in a 3 : 1 ethylene glycol-water mixture at 120°C.…”