Triclosan antimicrobial polymers

Abstract

Triclosan antimicrobial molecular fluctuating energies of nonbonding electron pairs for the oxygen atom by ether bond rotations are reviewed with conformational computational chemistry analyses. Subsequent understanding of triclosan alternating ether bond rotations is able to help explain several material properties in Polymer Science. Unique bond rotation entanglements between triclosan and the polymer chains increase both the mechanical properties of polymer toughness and strength that are enhanced even better through secondary bonding relationships. Further, polymer blend compatibilization is considered due to similar molecular relationships and polarities. With compatibilization of triclosan in polymers a more uniform stability for nonpolar triclosan in the polymer solid state is retained by the antimicrobial for extremely low release with minimum solubility into aqueous solution. As a result, triclosan is projected for long extended lifetimes as an antimicrobial polymer additive. Further, triclosan rapid alternating ether bond rotations disrupt secondary bonding between chain monomers in the resin state to reduce viscosity and enhance polymer blending. Thus, triclosan is considered for a polymer additive with multiple properties to be an antimicrobial with additional benefits as a nonpolar toughening agent and a hydrophobic wetting agent. The triclosan material relationships with alternating ether bond rotations are described through a complete different form of medium by comparisons with known antimicrobial properties that upset bacterial cell membranes through rapid fluctuating mechanomolecular energies. Also, triclosan bond entanglements with secondary bonding can produce structural defects in weak bacterial lipid membranes requiring pliability that can then interfere with cell division. Regarding applications with polymers, triclosan can be incorporated by mixing into a resin system before cure, melt mixed with thermoplastic polymers that set on cooling into a solid or alternatively applied as a coating through several different methods with dissolving into an organic solvent and dried on by evaporation as a common means.

Keywords: Antimicrobial; bond entanglements; bond rotation; computational chemistry; mechanomolecular; polymer; secondary bonding; strength; toughness; viscosity.

Figure 1

Triclosan molecule depicted as a planar molecule with no ether oxygen bond rotation.

Figure 2

(a) Computational energy profile with rotations of the ether oxygen bonds from 20° through 90° in 5 degree increments to include a 3D model of Triclosan at a 50° bond rotation. (b) 3D model with energy minimum at approximately a 30° bond rotation. (c) 3D model with energy maximum at a 90° bond rotation. Yellow arrows in (b) and (c) depict directions for the dipoles near the ether oxygen atom roughly toward the hydroxyl oxygen atom. 3D models as colors for atoms include: Oxygen-Red; Carbon-Grey; Hydrogen-White; Chlorine-Orange.

Figure 3

Triclosan oxygen ether bond rotations from 2D 0.0° rotation through to 180° in 3D: (a) Common 2D structure 0.0° ether bond rotation. (b) 3D structure 45.0° ether bond rotation. (c) 3D structure 90.0° ether bond rotation. (d) 3D structure 120.0° ether bond rotation. (e) 3D structure 150.0° ether bond rotation. (f) 3D structure 180.0° ether bond rotation with steric interaction between opposing aromatic hydrogen atoms.

Figure 4

Increasing average flexural strength values for triclosan incorporated into a BisGMA/TEGDMA photocure resin at 0 wt%, 5 wt%, 10 wt% and 20 wt%.

Figure 5

Condensing Index demonstrates increasing loss of paste consistency during compressive force gauge measurements at 0.0 wt%, 4.25 wt%, 8.41 wt% and 15.31 wt% triclosan added into the particulate-filled composite.

Figure 6

Bacteria with no nucleus attach chromosomes to the cell membrane that subsequently invaginates inward between the two circular-like chromosomes with a septum during the rapid binary fission process.

Figure 7

Triclosan molecules approach the bacterial membranes through the cell walls. Resultant vibrational molecular alternating bond rotation fluctuations by triclosan disrupt the membranes. Alternatively, triclosan creates structural defects by bond rotation entanglements or through aromatic intercalating ring stacking by secondary bonding into the phospholipid membranes [8].