Study of polymerization dynamics in micropores of Metal-Organic framework

Compared with bulk conducting polymers (CPs), conducting polymer nanostructures possess high electrical conductivity, large surface area, and superior electrochemical activity which make them suitable for several applications like energy storage devices, electrochemical sensors, drug delivery etc. Nanocomposites of CPs with other host molecules give them more valuable properties by making them multifunctional. Metal-organic frameworks (MOFs) porous crystalline materials have been increasingly investigated as templates for precise control of polymerization. Polymerizations within confined nanochannels of porous MOFs have shown unique confinement effect on polymer chain structures and polymer dynamics. Our present work investigates the alteration of properties upon nanoconfinement of CP PEDOT polymerized oxidatively in the micropores of MOF UiO-66. X-ray diffraction measurements confirmed inclusion of PEDOT in the MOF. Small shift of peak positions and decrease in intensities of the crystalline peaks with incorporation of PEDOT is observed. Fourier Transform IR (FTIR) spectroscopy showed different vibrational, (stretching, bending) modes of thiophene ring and ethylenedioxy groups present in PEDOT along with the modes of MOF. Confinement effect on crystallization of CP is observed by Differential Scanning Calorimetry (DSC). BET surface area measurements showed the change in surface area of PEDOT/MOF nanocomposite. Presence of PEDOT is also confirmed by Raman spectroscopy and inelastic neutron scattering is carried out to investigate the change in vibrational density of states after polymerization within the micropores.