Poly(ammonio alkoxydicyanoethenolate)s as new hydrophobic and highly dipolar polyzwitterions: 3. Solubility properties

Towards highly functionalized and semi-rigid polyzwitterions, 1. Poly(dizwitterionic methacrylates): synthesis and specific properties

“…First, the possibility of varying the length of the spacer (p, q) between the methacryloyl and the dizwitterionic moieties is of definite interest since it is likely a major factor of the polymerizability of the monomer and of the tacticity and rigidity of the corresponding polymer. Second, the ammonioethoxydicyanoethenolate moiety is a very stable, highly dipolar 20) (l L 26 D) and hydrophobic zwitterion which imparts to the corresponding monofunctional poly(methacrylate) 21) (reference polyzwitterion P(Z), as given in Scheme 1) a fairly broad solubility range in organic solvents 22) and a strongly decreased hydrophilicity with respect to more classical zwitterionic structures 23) such as ammonio alkylcarboxylates or sulfonates. The following nomenclature is adopted throughout the text: the figure 1 to 4 is related to the monomer type (see Scheme 1) and the following symbols A2, AZ, Z2 are related to the diamino precursor, the monoamino-monozwitterionic and the dizwitterionic derivatives, respectively.…”

“…3. Here again, as for dipolar aprotic solvents, solubility in concentrated aqueous salt solutions and its dependence upon temperature (UCST) and ionic strength are thus parallel for P(4-Z2) and P(Z) 22) : No T c observed up to 180 8C (irreversible discolouration of the solution).…”

“…Solubility is essentially restricted to m-cresol (high polarizability) and it remains very weak (less than 1 g N dL -1 ) in fluorinated alcohols such as trifluoroethanol or hexafluoroisopropyl alcohol. This major difference with P(Z) 22) still remains puzzling. Specific chain solvation through hydrogen bonding between the anionic sites of the dizwitterionic structure and these weakly self-associated alcohols of the highest hydrogen bond-donor strength should also be efficient for P(4-Z2).…”

“…The comprehensive discussion of the polyzwitterion solubility (in terms of dipole moment, polarizability, and basicity of the solvents) and of its dependence upon temperature (LCST) and salt addition previously advanced for P(Z) 22) may be directly transposed to the case of P(4-Z2).…”

“…These properties were essentially analyzed for polymer P(4-Z2) and compared with those of the reference monozwitterionic poly(methacrylate) P(Z) previously studied 22) . P(4-Z2) is essentially soluble at room temperature in three different types of solvents which will be discussed successively: a) Aprotic solvents.…”