Development of an antimicrobial microporous polyurethane membrane

https://doi.org/10.1016/j.memsci.2006.11.054Get rights and content

Abstract

To impart antimicrobial property, a moiety of 2,2,5,5-tetramethyl-imidozalidin-4-one (TMIO) hydantoin was successfully grafted onto microporous polyurethane (PU) membrane surface as an N-halamine precursor through a two-step grafting procedure. A combination of techniques was used to confirm the surface grafting. Thermal and mechanical properties of modified PU membranes were evaluated accordingly. Upon exposure to chlorine bleaching, the hydantoin structures on the grafted PU membranes were transformed into N-halamines. Energy-dispersive X-ray (EDX) microanalysis and iodometric titration were used to analyze the chlorine contents of the PU membranes after chlorination. A total reduction of both Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria) was observed after a 2-h contact period. Water vapor transmission rate (WVTR) remained essentially unchanged after surface modification with TMIO. Consequently, a microporous PU membrane that not only possesses good barrier and hygiene protections, but also maintains sufficient WVTR for comfort was developed.

Introduction

With the growing public health awareness of disease transmissions, cross-infections and malodors caused by microorganisms, use of antimicrobial materials has increased in many application areas, especially as protective clothing for medical and chemical workers, first receivers, sportswear, underwear and other health related products [1], [2], [3], [4], [5], [6], [7], [8]. Depending on the applications, materials can be physically fabricated by making them monolithic to be impermeable to challenging microorganisms, by controlling microporous pore sizes, or applying a layer of coating to restrict or block the penetration of pathogens and viruses [9]. Antimicrobial materials can be chemically engineered by adding functional antimicrobial agents onto the surface or within the matrix to either kill or inhibit the growth of microorganisms. Commonly used antimicrobial agents, such as antibiotics, silver ions, quaternary ammonium, N-halamines, and other biocidal agents, can be applied onto textiles and membrane materials by various chemical and physicochemical finishing techniques to protect the substrates from biological activities [10], [11], [12], [13].

For enhanced performance, an antimicrobial material should not only have good barrier and hygiene properties to protect wearers from pathogens and microbes, but also allow moisture and heat transport to prevent heat stress of the wearer. Microporous polyurethane (PU) membrane has numerous interconnected pores inside the membrane, which gives it desired breathability and some restrictions to particles, including chemical and pathogens, larger than the pore size [9]. In addition, PU membrane is very versatile and can be easily functionalized; therefore, microporous PU membrane was selected as the initial substrate for the study of antimicrobial properties.

The purpose of this research was to design a multifunctional membrane material, which possesses antimicrobial properties and maintains the balance between comfort and protection, i.e. water vapor transport and barrier protection [14]. To achieve the antimicrobial properties, N-halamine moieties were incorporated onto the membrane surfaces.

Section snippets

Materials

Microporous polyurethane (PU) membranes, with different pore sizes up to 8 μm and an average thickness of 50 μm, were obtained from Porvair Com., Norfolk, UK. 2,2,5,5-Tetramethyl-imidozalidin-4-one (TMIO, HaloSource Corporation, Seattle, WA) was used as an N-halamine precursor to modify the PU membrane surfaces. Toluene (Mallinckrodt Baker Inc., Phillipsburg, NJ) was dried over 4 Å molecular sieves (EM Science, Gibbstown, NJ) for 48 h before use. Hexamethylene diisocyanate (HMDI), tin (II)

Spectra analysis

Surface grafting was confirmed by ATR–FTIR (Fig. 1). After the first step reaction as shown in Scheme 1(a), the characteristic peak centered around 2250 cm−1 resulting from the stretching oscillation of the isocyanate (–NCO) group appeared, indicating a successful functionalization of the PU membrane surface with HMDI. After the second step grafting reaction with TMIO, this characteristic isocyanate group disappeared suggesting another reaction occurred on the membrane surface. Few other

Conclusions

To achieve surface antimicrobial property, TMIO was successfully grafted onto microporous polyurethane (PU) membrane surface as an N-halamine precursor. ATR–FTIR, 1H NMR, and XPS characterizations confirmed the surface chemical composition changes due to the surface grafting of TMIO moieties. EDX microanalysis and iodometric titration results showed that upon chlorination, the grafted TMIO hydantoin structures were successfully converted into N-halamines. SEM micrographs indicated that surface

Acknowledgements

This research was supported in part by the Cornell University Human Ecology College Grant and by the National Textile Center (Project C05-CR01). This work made use of the Cornell Center for Materials Research Shared Experimental Facilities, supported through the NSF MRSEC program (DMR-0079992). The LEO 1550 SEM was originally funded by the Keck Foundation, with additional support from the Cornell Nanobiotechnology Center (STC program, NSF award # ECS-9876771). The authors also thank Dr. Gang

References (36)

  • M.A. Montecalvo et al.

    Infection-control measures reduce transmission of vancomycin-resistant enterococci in an endemic setting

    Ann Intern Med

    (1999)
  • G. Sun et al.

    A novel cyclic N-halamine biocidal polymer

    Polym Prep (Am Chem Soc Div Polym Chem)

    (1994)
  • M. Braun et al.

    Antimicrobial polymers containing melamine derivatives. Part I. Preparation and characterization of chloromelamine-based cellulose

    J Polym Sci A: Polym Chem

    (2004)
  • L.R.M. Estevao et al.

    Development of polyurethane antimicrobial composites using waste oil refinery catalyst

    Ind Eng Chem Res

    (2003)
  • S.D. Worley et al.
  • Lee S, Obendorf SK. Barrier effectiveness and thermal comfort of protective clothing materials. J Text Inst (in...
  • D. Briggs et al.

    Practical surface analysis

    (1983)
  • K. Dusek et al.

    Network formation of polyurethanes due to side reactions

    Macromolecules

    (1990)
  • Cited by (110)

    View all citing articles on Scopus
    View full text