Glasnik hemičara,tehnologa i ekologa Republike Srpske, 4(2010) 13-14

13

MORPHOLOGY OF ELECTROCONDUCTIVE COMPOSITE SYSTEMS

V. BUKOŠEK1, G.K. ELYASHEVICH2 1University of Ljubljana, Faculty for Natural Sciences and Engineering, Ljubljana, Slovenia,

2Institute of Macromolecular Compounds, Russian Academy of Sciences, Saint-Petersburg, Russia

ISSN 1840-054X UDC 661.78:541.49

Plenarno predavanje

Conducting polymers attract considerable attention because of their unique electrical, optical and electrooptical properties and numerous potential applications for: batteries, electrochromic displays, ion-exchange materials, membranes, sensors, corrosion protection, antistatic materials, etc. The conducting materials with various configurations may be prepared by a modification of desired supports. Polypyrrole (PPy) and polyaniline (PANI) are promising polymers for the preparation of electroconducting materials due to their high specific conductivity, good chemical stability and compatibility with polymer supports. However, potential applications of these polymers are restricted by poor mechanical properties – low strength and high brittleness. The most efficient solution for this problem is composite systems where a polymer support provides good mechanical properties, and a conducting polymer acts as an active component. Microporous polyethylene (PE) films were used as elastic supports, and PPy and PANI as electroconducting components.

Microporous polyethylene films were prepared from HDPE (Mw = 140 000) in the process, based on the melt extrusion technique with subsequent annealing, uniaxial extension and thermofixation.[1] These PE films contain a large number of pores (0.05-0.45 mm in size). The composite systems were prepared by the formation of PPy and PANI layers onto microporous PE films [2,3] by oxidative polymerization of pyrrole in water-methanol solutions, and from aqueous aniline hydrochloride solutions. For unveiling morphologycal structures the JEOL JSM 6060LV scanning electron microscope (SEM) was used.

λ=12.7 λ=24 λ=24+2

Figure 1 –SEM photographs of porous PE at different draw ratio λ, magnification 20 000X.

The porous PE films, Figure 1, have a strongly developed lamellar and fibrous structure, with clearly visible lamellae and microfibrils. Morphology of PE porous supports demonstrate that the increase of draw ratio leads to the formation of the more orientated structure and number of deep pores with tie “nanofibrils”, a dimension of about 100 nm, connecting the lamellae. The surface relief of the films includes the extended structure details which have an oriented character. This structure of the surface is similar to the inner lamellar structure of the porous films which has a lower scale of structure details.[4]

The morphology of conducting layers of PPy on the porous PE film surface, Figure 2, becomes more dense and homogeneous when the orientation degree of PE porous support increases.

The same valid for conducting layers of PANI on the porous PE film surface, Figure 3, which becomes more dense and homogeneous with the orientation of PE porous support. Better orientation means better conductivity.

V.Bukošek, Morphology of electroconductive composite systems

14

λ=12.7 λ=24 λ=24+2

Figure 2 –SEM photographs of conducting layers of PPy at different draw ratio , magnification 20 000X.

λ=12.7 λ=24 λ=24+2

Figure 3 –SEM photographs of conducting layers of PANI at different draw ratio λ, magnification 20 000X.

The morphologycal structures of PE samples demonstrate that the increase of draw ratio, leads to the formation of more orientated and microporous structure with number of “nanofibrils” (100 nm).

Polypyrrole, PPy, and polyaniline, PANI, conducting layers on the microporous polyethylene, PE, film surface becomes more dense and homogeneous when with draw ratio the oriention degree of microporous polyethylene support increases.

The electroconducting component is deposited not only on the film surface but also on the walls of pores, which leads to the formation of continuous phase of conducting polymer and better volume conductivity [5, 6, 7]. Conducting composite materials, PE/PPy, PE/PANI, are characterized by a high adhesion and continuous phase of conducting polymer on porous support.

References 1. G.K. Elyashevich, et al. Sizes of through-channels in microporous polyethylene films. Polym. Sci. (Transl. of

Vysokomol. Soedin.), 1998, 40A, 567.

2. G.K. Elyashevich, et al., Composite membranes with conducting polymer microtubules as new electroactive and transport systems. Polym. Adv. Technol. 2002, 13, 725. DOI:10.1002/pat.251.

3. G.K. Elyashevich, et al., Properties of multi-layer composite membranes on the base of polyethylene porous films. Desalination, 2002, 144, 21

4. G.K. Elyashevich, M.A. Smirnov, I.S. Kuryndin, V. Bukošek. Electroactive composite systems containing high conductuve polymer layers on polyethylene porous films. Polymers for Advanced Technologies, 2006, v.17, p. 700-704.

5. М.А. Смирнов, И.С. Курындин, Л.Н. Никитин, А.В. Сидорович, Ю.Н.Сазанов, О.В.Кудашева, В. Букошек, А.Р. Хохлов, Г.К. Ельяшевич. Свойства электропроводящих композиционных систем, содержащих слои полипиррола на пористых пленках полиэтилена. Журн. прикл. химии, 2005. т.78. вып.12. c. 2023-2032.

6. М.А.Смирнов, В.Букошек, Л.Н.Никитин, А.Р.Хохлов, Г.К.Ельяшевич. Структура и электропроводность полипиррола в композиционных системах на основе пористых пленок полиэтилена. Четвертая всероссийская каргинская конференция «Наука о полимерах 21-му веку» (Москва, 29 янв.-2 февр. 2007), т. 2 с. 259.

7. V. Bukosek, G.K.Elyashevich. Conductive composite systems on the basis of PE/PPY and PE/PANI. European Polymer Congress- 2007, Portoroz, Slovenia, July 1-7, 2007, p. 255.