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

摘要

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 -CH2-CH(CH2Ri)-O- of finely tuned polarity such as epichlorohydrin (PEC, R-i=Cl), glycidol (PGOH, R-i=OH), glycidyl acetate (PGAC, R-i=O-CO-CH3) or glycidyl p-nitrobenzoate (PGNB, R-i=O-CO-C6H4-NO2) and highly dipolar and constant B units -CH2-CH[-CH2-O-(CH2)(2)-N+(C2H5)(2)-(CH2)(2)-O-CO-C-(CN)(2)]-O- of the ammonioethoxydicyanoethenolate type (mu = 25.9 D, molar fraction F-B ( 0.3). The bulk structure of the various zwitterionomers was analyzed by differential scanning calorimetry (glass transitions) and solid state NMR (H-1 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 polymeric matrices (A(i))(n). a) PGOH zwitterionomers are monophasic (one T-g between 3 and 31 degreesC) as a result of specific A-B hydrogen bonding, b) PGNB zwitterionomers are likely monophasic tone T-g around 58 degreesC) 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 thigh T-g approximate to 22 degreesC) and a segregation rate of PEC units in the "soft" phase (low T-g approximate to -18 degreesC) of about 84%. d) PGAC zwitterionomers are monophasic (one T-g between -12 and 15 degreesC), despite fairly close and weak Van der Waals A-B interactions and fairly similar matrix mobility when compared to the previous PEC case. Thus, microphase separation in model A(i)B random zwitterionomers appears very sensitive towards small variations of the matrix polarity and of the A-B interactions. [References: 27]