Matrix polarity effects on microphase separation in zwitterionomers, 2. Structural analysis of the model random zwitterionomers

Matrix polarity effects on the potential microphase separation in zwitterionomers were analyzed on four homologous series of model zwitterionic A i B copolymers. They combine in their chain various A i units -CH 2 -CH(CH 2 R i )-O- of finely tuned polarity such as epichlorohydrin (PEC, R i =Cl), glycidol (PGOH, R=OH), glycidyl acetate (PGAC, R i =O-CO-CH 3 ) or glycidyl p-nitrobenzoate (PONB, R i -O-CO-C 6 H 4 -NO 2 ) and highly dipolar and constant B units -CH 2 -CH[-CH 2 -O-(CH 2 ) 2 -N + (C 2 H 5 ) 2 -(CH 2 ) 2 -O-CO-C - (CN) 2 ]-O- of the ammonioethoxydicyanoethenolate type (μ = 25.9 D, molar transtion F n < 0.3). The bulk structure of the varions zwiterionomers was analyzed by differential scanning calcrimetry (glass transitions) and solid state NMR CH dipolar line shape analysis, chain dynamics) and correlated with the solubility properties of a model zwitterion in a series of solvent models of the various polymetic matrices (A i ) n . a) PGOH zwitterionomers are monophasic (one T g between 3 and 31°C) as a result of specific A-B hydrogen bonding, b) PGNB zwitterionomers are likely monophasic (one T g around 58°C) as a result of strong dipolar and dispersion A-B interactions but this feature cannot be definitely ascertained because of the too close glass transitions of the parent homopolymers c) The PEC zwitterionomer of F B = 0.11 is a biphasic material characterized by a quasi-quantitative segregation of the dipolar units in the hard phase (high T g ≃ 22°C) and a segregation case of PFC units in the soft phase (low T g ≃ -18°C) of about 84%. d) PGAC zwitterionomers are monphasic (one T g between -12 and 15°C), despite larly close and weak Van der Waals A-B interactions and study simular matrix mobility when compared to the previous PEC case. Thus, microphase separation in model A.B random zwitterionomers appears very sensitive towards small variations of the matrix polarity and of the A-B interactions.