Facile Synthesis of Zwitterionic Diblock Copolymers without Protecting Group Chemistry

Abstract

A versatile new route to zwitterionic diblock copolymers that avoids protecting group chemistry is reported. Various tertiary amine methacrylates are block copolymerized with 2-hydroxyethyl methacrylate to produce hydroxy-functional diblock precursors via sequential monomer addition. These low-polydispersity precursors are then treated with succinic anhydride under mild conditions to produce a range of new near-monodisperse zwitterionic diblock copolymers in which both blocks are weak polyelectrolytes. Thus, the final copolymers exhibit complex aqueous solution behavior (isoelectric points, schizophrenic micellization behavior, etc.) depending on the solution pH.

Assembly of polyelectrolyte-containing block copolymers in aqueous media

“…Other systems are more responsive; PEA-PMAA (I-A) micelles dissociate completely upon increasing the degree of ionization [13]. Bories-Azeau et al [15] synthesised zwitterionic diblock copolymers (C-A), whose self-assembly depends on pH and which form micelles with either a cationic or an anionic corona block. Another pH-responsive DBCP (of S-C type) forms only one type of aggregates.…”

Synthesis of pH-responsive tertiary amine methacrylate polymer brushes and their response to acidic vapour

“…23 They propose that this 5 effect becomes more pronounced with increasing grafting density. Indeed, the most densely grafted brush in their study is still deswollen at pH 4 (pK a of the free polymer = 7.3 19 ). To verify this pK a shift for PDEA brushes, and to attempt to reproduce the effect in PDPA, brush-coated wafers (dry 10 thicknesses = 51 nm for PDEA and 48 nm for PDPA) were exposed to buffer solutions of incrementally reduced pH and the ellipsometric parameters were recorded using in situ ellipsometry.…”

“…Whereas PDMA and PDEA have similar pK a values (7.0 and 7.3 respectively, as measured for untethered homopolymers in dilute solution), PDPA has a significantly lower pK a (6.3). 19 In addition, while PDMA is water-soluble in both its protonated and unprotonated state, the more hydrophobic PDEA and PDPA 75 chains show pH-dependent solubility, being solvated only when protonated (i.e. below their pK a values).…”

Stimuli responsive amphiphilic block copolymers for aqueous media synthesised via reversible addition fragmentation chain transfer polymerisation (RAFT)

“…By virtue of the higher chemical tolerance of free radical polymerisation compared to other polymerisation methods, these methods offer a more convenient, and a much more versatile access to block copolymers bearing polar and hydrophilic moieties. The increased variability of monomer units for block copolymer synthesis has stimulated the efforts to convert macro-surfactants from static structures to dynamic ones, in which the amphiphilicity responds to environmental changes [1,22,23,[35][36][37][38][39][40][41][42]. For instance incorporating a stimuli-sensitive hydrophilic block, one can switch in water from soluble to insoluble, and thus control the amphiphilic behaviour: if the other block is hydrophobic (Scheme 1(b)), the polymer behaves as surfactant in the ground state, and as oily compound after applying the stimulus.…”