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Relaxation dynamics of blends of PVDF and zwitterionic copolymer by dielectric relaxation spectroscopy
Author(s) -
Clark Andrew G.,
Salcedo Montero Miriam,
Govinelaka D.,
Lounder Samuel J.,
Asatekin Ayse,
Cebe Peggy
Publication year - 2020
Publication title -
journal of polymer science
Language(s) - English
Resource type - Journals
eISSN - 2642-4169
pISSN - 2642-4150
DOI - 10.1002/pol.20200032
Subject(s) - copolymer , dielectric , materials science , relaxation (psychology) , dissipation factor , conductivity , dielectric spectroscopy , arrhenius equation , polymer chemistry , phase (matter) , methacrylate , analytical chemistry (journal) , dielectric loss , chemistry , polymer , composite material , organic chemistry , activation energy , electrochemistry , optoelectronics , psychology , social psychology , electrode
Relaxation dynamics of PVDF blended with a random zwitterionic copolymer ( r ‐ZCP) of methyl methacrylate and zwitterionic sulfobetaine‐2‐vinylpyridine (PMMA‐ r ‐SB2VP) were investigated using dielectric relaxation spectroscopy. FTIR spectroscopy was used to determine the PVDF crystal phase of compression molded blends. Adding 25 wt% of r ‐ZCP promoted the formation of the polar β and γ crystals over the nonpolar α phase. A structural model is proposed where the r ‐ZCP biases the PVDF to form polar crystal phases. Boyd's model was used to calculate the room temperature dielectric constants and led to good agreement with our measurements. Dielectric spectra of neat r ‐ZCP showed two relaxation peaks attributed to PMMA units, with no additional relaxations present from the zwitterions. Blends of PVDF with r ‐ZCP were dominated by the α c relaxation associated with the crystalline phase of PVDF, which showed an Arrhenius temperature dependence. Analysis of the conductivity spectra shows a larger DC conductivity in the blends than in either r ‐ZCP or homopolymer PVDF. Blends show an additional peak in the loss tangent, absent in the copolymer or PVDF attributed to space‐charge polarization. Higher DC conductivity and space‐charge polarization indicate that the combination of zwitterions and unique microstructure affects charge transport properties.