Synthesis and characterisation of sterically stabilised polypyrrole particles using a chemically reactive poly(vinyl amine)-based stabiliser
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Poly(vinyl amine) (PVAm) was derivatised using 2-thiophenecarboxaldehyde via Michael addition to prepare a statistical copolymer stabiliser for the synthesis of primary amine-functionalised polypyrrole (PPy) particles. A minimum stabiliser concentration of around 20 % (w/v) relative to pyrrole was required for well-defined PPy particles of approximately 100–200 nm, as judged by transmission electron microscopy (TEM) and dynamic light scattering (DLS). FTIR spectroscopy confirmed that stabiliser grafting had occurred, while x-ray photoelectron spectroscopy (XPS) studies indicated a stabiliser surface coverage on the PPy particles of around 53 %. PPy particles prepared at stabiliser concentrations below 20 % (w/v) were not colloidally stable above pH 6. However, higher stabiliser concentrations (e.g., 50 % (w/v) based on pyrrole) led to a significant improvement, with colloidal stability being retained above pH 7. Long-term colloidal stability studies of PPy particles stored at pH 7.5 confirmed that the amine-based stabiliser produced more stable aqueous dispersions than the imine-based stabiliser, since the latter bond is hydrolytically unstable.
KeywordsPolypyrrole Primary amine Aqueous dispersion polymerisation Immunodiagnostics Chemical grafting Steric stabilisation Conducting polymer
METRC is thanked for funding this study via a proof-of-concept grant. Vivacta Ltd. (Sittingbourne, UK) is also thanked for partial support of this work. BASF (Ludwigshafen, Germany) is acknowledged for the kind gift of the poly(vinyl amine) precursor. Amy Walsh is thanked for sharing her acid titration data for poly(vinyl amine).
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