Use of poly(ethylene terephthalate) track membranes as template matrices for the preparation of polymeric nanomaterials based on polypyrrole and poly(N-methylpyrrole)

Abstract

Ion-track nanotechnologies for the formation of micro-and nanostructures from various materials, in particular, metals and alloys as nanowires and microtubes, with the use of polymer track membranes as template matrices have received increasing attention in the last few years [1,2]. Track membranes have also been used as templates for the synthesis of nanopolymeric materials, which, in particular, possess membrane properties [3,4]. However, research in this area of iontrack technology is in its infancy and many kinetic and structural features of the formation of polymeric microand nanostructures on polymer templates, as well as the physicochemical and other properties of micro-and nanopolymers synthesized, are still poorly known. Therefore, systematic studies aimed at determining the general features of the polymerization of structurally different monomers on polymer templates, as well as studies on the structure and properties of micro-and nanopolymeric materials thus prepared, are of undoubted scientific and practical interest for the development of this area of ion-track nanotechnology.In this paper, we report preliminary results concerning the polymerization of monomers, such as pyrrole and N -methylpyrrole, on poly(ethylene terephthalate) (PET) membranes with micron-sized pores (1.2-5 µ m). The structure and properties of nanopolymeric membranes synthesized from these monomers were also studied. Note that conducting nanopolymeric materials can be prepared from polypyrrole and its derivatives.These materials can find various applications in technology and medicine, for example, as biosensors [5][6][7]. EXPERIMENTALTrack membranes based on PET films of 10-12 µ m in thickness with various initial parameters (pore diameter d , pore length l , and porosity δ ) (Table 1) were taken as templates. The PET track membranes were obtained in the Flerov Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research (Dubna). The polymer films were irradiated with accelerated multicharged ions of xenon with an energy of 1 MeV/nucleon on a U-400 cyclotron (fluence of 2 × 10 8 cm -2 ); next, the films were irradiated with UV light at λ ≥ 300 nm in air for 60 min at room temperature. Thereafter, the films were subjected to alkali etching in 3 M NaOH at 338 K for 30 min [8,9].Abstract -The oxidative polymerization of pyrrole and N -methylpyrrole with the use of template synthesis on poly(ethylene terephthalate) (PET) track membranes was studied. By scanning electron microscopy (SEM), it was found that a polymer film was formed on the surface of membranes and on the walls of membrane pores. The rates of polymerization on the surface of membranes and pore walls, as well as the yield and structure of the polymer film, depend on the membrane parameters (pore length and diameter and membrane porosity), the chemical structure of the monomer, the diffusion of polymerized solutions through template pores, and the temperature.

Structure of Conducting Polymer Films Prepared on the Surface and in the Pores of Poly(ethylene terephthalate) Track Membranes by Template Synthesis

“…In polymerization in a cell, a monomer solution is placed on the one side of a template membrane and a solution of an oxidizing agent is placed on the other side [11]. Therefore, in the general case, it is believed that polymer films on the opposite sides of a template will be different in thickness.…”

“…The PET track membranes were prepared and the polymers were synthesized on these membranes in accordance with the procedure described previously [11].…”

“…The water permeability of membranes was determined to evaluate granular PPy in the pores of polished modified membranes. For this purpose, a polymerization cell was used (the cell was schematically shown elsewhere [11]). The left chamber of the cell was connected by flexible tubing to a vessel with twice-distilled water, and the right chamber was connected to a receiver coupled to a water-jet pump, which generated a vacuum.…”

“…where S polymerization = 2 S is the total surface area accessible to polymerization, m 2 (the equation was derived in [11]); S is the surface area of the track membrane, m 2 ; ρ PPy is the density of PPy (1350 kg/m 3 [12]). …”

“…Previously [11], we considered in detail the following parameters of the oxidative polymerization of PPy and poly( N -methylpyrrole) on PET track membranes: the rates of polymerization on the surface of membranes and on pore walls and the yield and structure of the film polymer. We found that these parameters depend on the characteristics of parent membranes (pore diameter and length and membrane porosity), the chemical structure of the monomer, the diffusion of polymerized solutions through template pores, and the temperature.…”