Surface morphology molecular imprinted polymers based on polyimide

Abstract

In the study polymers with molecular imprints of sodium benzoate on the surface of the electrodes of pie-zoelectric sensors were obtained. The widespread use of preservatives in the food industry contributes to the devel-opment of express methods for their analysis with modified piezoelectric sensors. The purpose of the study was the analysis of the surface morphology of polymers with molecular imprints obtained based on polyimide by scanning force microscopy.
Polymers with molecular imprints were obtained based on copolymer of dianhydride 1,2,4,5-benzenetetracarboxylic acid with 4,4'-diaminodiphenyl oxide, produced by JSC MIPP NPO "Plastic", Moscow. Sodium benzoate was used as a template. The prepolymerisation mixture was applied on the surface of the elec-trodes of the piezoelectric sensors with a spatula or by stamping. Thermal imidisation was carried out in an oven in two stages: the first stage was performed at 80oC, the second at 120oC. After film polymerisation, the sensors were cooled to room temperature, then placed in distilled water for 24 hours for the removal of the template.
The study of the surface morphology of the obtained polymer films was carried out using a scanning force microscope (SSM) "Solver P47 PRO" manufactured by JSC "NT-MDT" in the semi-contact mode using NSG03 probe with a stiffness of 1.74 N/m. The images were processed using the FemtoScan-001 software.
Analysis of the surface morphology of the films showed that the application of the prepolymerisation mixture with a stamp led to the formation of a more uniform surface with a height difference from 1.4 to 2.6 nm. The use of a spatula led to the formation of a rougher surface with heights in the range of 0.9-3.4 nm. Thus, the proposed method of the application of the mixture is promising since it allows obtaining surfaces with more reproducible thickness and roughness, which will improve the accuracy of the analysis of substances by piezoelectric sensors modified by these polymers.
It should considered that during the formation of a polymer film, template molecules are partially or com-pletely emerged in the polymer matrix, and they are also located on its surface, forming globular structures. Extrac-tion of the template from the polymer surface led to the appearance of cavities complementary to sodium benzoate molecules.