Heterogenized Imidazolium-Based Ionic Liquids in Pebax®Rnew. Thermal, Gas Transport and Antimicrobial Properties

Abstract

Imidazolium-based ionic liquids (ILs) have interesting antimicrobial activity and their inclusion in a flexible film is ideal to take advantage of their properties in practical applications. Poly(ether-block-amide) (Pebax®Rnew) films were prepared by solution casting, loading two synthetized ILs (1-hexadecyl-3-methylimidazolium dimethyl-5-sulfoisophthalate [Hdmim][DMSIP], IL1 and 1-octyloximethyl-3-methylimidazolium hexafluorophosphate [OOMmim][PF6], IL2) up to 5 wt.%. The ILs were characterized by 1H NMR and MALDI-TOF spectroscopy. The films were investigated for miscibility, morphology, wettability, spectral properties and gas transport. The films display a good thermal stability (>200 °C). Differential scanning calorimetry (DSC) proves phase separation in the blends, that is consistent with FTIR analysis and with the island-like surface morphology observed in the micrographs. Gas permeability tests revealed that the IL-loaded films are dense and poreless, keeping the selectivity of the polymer matrix with a somewhat lessened permeability owing to the impermeable ILs crystals. The film antimicrobial activity, evaluated against Gram-negative and Gram-positive bacterial strains, was correlated to the structure of the incorporated ILs. The smaller IL2 salt did not modify the hydrophobic nature of the neat polymer and was readily released from the films. Instead, IL1, having a longer alkyl chain in the cation, provided a promising antimicrobial activity with a good combination of hydrophilicity, permeability and thermal stability.

Polymer Blends Based on 1-Hexadecyl-3-methyl Imidazolium 1,3-Dimethyl 5-Sulfoisophthalate Ionic Liquid: Thermo-Mechanical, Surface Morphology and Antibacterial Properties

“…The synthesis description of the ionic liquid 1-hexadecyl-3-methylimidazolium 1,3-dimethyl 5-sulfoisophthalate (HdmimDMSIP) was previously reported [ 11 , 12 ]. Scheme 2 displays the two steps of the synthesis.…”

“…The World Health Organization of the United Nations (WHO-UN) has reported an increase in bacterial resistance in SSTIs, highlighting that the phenomenon regards Gram-negative pathogens such as E. coli [ 4 ]. In order to avoid the excessive use of antibiotics, research on alternative biocides, both natural [ 5 , 6 , 7 ] and synthetic with original structures [ 8 , 9 , 10 , 11 , 12 , 13 , 14 ], has recently been increasing.…”

“…[ 20 ]. They have been added into PMMA, PVC, PBT, PVA, PC, PET, and Pebax ® Rnew matrices as plasticizer [ 21 , 22 , 23 ], dispersant [ 24 ], and/or antimicrobial agents [ 11 , 12 , 25 , 26 , 27 , 28 ]. Nevertheless, to the author’s knowledge, the studies on antimicrobial SEBS blends do not include the loading of ILs into SEBS matrices as antimicrobial agents.…”

Ionic Liquids—A Review of Their Toxicity to Living Organisms

“…The role of ILs as antimicrobial agents in polymeric films for medical applications was studied recently [ 56 ]. This work evaluated the antimicrobial activity of 1-hexadecyl-3-methylimidazolium dimethyl-5-sulfoisophthalate ([C 16 mim][DMSIP]) and 1-octyloximethyl-3-methylimidazolium hexafluorophosphate ([C 8 OC 1 mim][PF 6 ]) in a commercial polymer Pebax ® Rnew, against five bacteria ( E. coli , Pseudomonas fluorescens (P. fluorescens) , Salmonella enterica (S. enterica) , L. monocytogenes and B. subtilis ).…”

Polyether Block Amide as Host Matrix for Nanocomposite Membranes Applied to Different Sensitive Fields

“…Pebax ® Rnew was successfully combined with Imidazolium-based ILs producing flexible films with antibacterial behaviour by solution casting [59]. Pebax ® Rnew is a plasticizer-free TPE copolymer that comprises polyamide 11 domains obtained from castor oil.…”