Smart Molecularly Imprinted Polymer Based on Liquid Crystals for Herbicide Recognition

Abstract

This study focuses on the development and characterization of molecularly imprinted thin films in the absence and presence of a liquid crystal monomer, as well as the evaluation of these materials for recognition of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Molecular imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were prepared by using two functional monomers, n-butylmethacrylate (BMA) and liquid crystalline (LC) 6-(4-cyanophenyl-4′phenoxy) hexyl acrylate (A6OCB). The resulting (MIPs) and (NIPs) materials were characterized by infrared spectroscopy (FTIR), Raman spectroscopy, polarized optical microscopy (POM), and atomic force microscopy (AFM). The entire monomer consumption, as well as the successful loading and extraction of the 2,4-D molecules, were validated by FTIR and Raman analyses. POM and AFM characterization revealed that the percentage of liquid crystal influenced the distribution of the liquid crystal domains and that the MIP films exhibited remarkable porosity. The experimental results revealed that the MIP films had a substantially higher adsorption capacity toward 2,4-D than the NIP materials and that increasing the liquid crystal content increased the adsorption capacity of both the MIP and NIP films. The selectivity tests in the presence of phenoxyacetic acid (POAc) showed that the MIP films exhibited higher affinity for 2,4-D than for the POAc.

Keywords:

• 2,4-D extraction
• imprinted polymer
• liquid crystal
• recognition capacity
• selectivity factor

Acknowledgments

The authors gratefully acknowledge the support of the Algerian Ministry of Higher Education and Scientific Research (MESRS), the General Directorate of Scientific Research and Technological Development (DGRSDT) of Algeria, the CRAPC Center, the University of Tlemcen in Algeria, the CNRS and IS2M institute.

Disclosure statement

No potential conflict of interest was reported by the author(s).