Antibacterial Nonwovens using

Nanophase Mn Oxide-Violet

Colored (NMO-V) or Nanophase

Mn Oxide Coated Fabrics-Violet

Colored (NMOC-V).

Rajan K. Vempati ChK Group, Inc., Plano, TX

Gajanan BhatThe University of Tennessee, Knoxville, TN

Richard WagnerPhycoBiologics, Inc.,Bloomington, IN

Nanophase Mn Oxides

(NMO)

Chemistry

Mn OxidesManganese oxide is any of a variety of manganese oxides hydroxides and oxyhydroxides These include:

• Manganese(II) oxide, MnO

• Manganese(II,III) oxide, Mn3O4

• Manganese(III) oxide, Mn2O3

• Manganese (IV) oxide, MnO2

• Manganese(VII) oxide - potassium permanganate

• Mn(IV) and Mn(II) oxides are the most common forms in nature

• Mn(IV) oxide – most stable form of Mn oxides

• Natural Mn oxides mostly crystalline structure

Mn Oxides Colors

Manganese oxide have distinctive colors:

• Manganese(II) oxide, MnO (pink colored)

• Manganese(II,III) oxide, Mn3O4

• Manganese(III) oxide, Mn2O3 (green colored)

• Manganese (IV) oxide, MnO2 (brown-black colored)

• Manganese(VII) oxide - potassium permanganate (violet)

Nanophase Mn Oxides

• ChK Group first to report stabilization of various Mnoxidation in solid (mineral) forms using phenylenediamines (PDA) isomers – based on color and UV-visible spectroscopy

• Formed stable nanoparticles – (Nano Mn Oxides – NMO)

- NMO-II

– NMO-III

– NMO- VII

Vempati and Son, 2006; U.S. Patent No. 6,953,763

Nanophase Mn Oxides

• Color distinct and stable

– NMO-Pink (Mn(II) Oxide – P)

– NMO-Green (Mn(III) Oxide – G)

– NMO-Violet (Mn(VII) Oxide – V)

• Stable color indicates stable oxidation state

• Normally would be reduced to black-brown color in aerobic environment

- NMO-Brown or Black (Mn(IV) Oxide – B)

Various NMOs Stabilized by Different

Phenylenediamine (PDA) IsomersNH2

NH2

NH2

NH2

NH2

NH2

o-PDA m-PDA p-PDA

NMO-P (Pink; II) Stabilized with o-PDA

– Neutral pH 7

NMO-G (Green; III) Stabilized with p-PDA dihydrochloride

– Acidic pH 2-3

NMO-V (Violet; VII) Stabilized with p-PDA

– Neutral to basic pH 7-8

Nanophase Material

Nanophase Versus Crystalline Phases

• Particle Size <100nm

•Higher surface area

•Highly reactive

NMO-V SEM Image

Nanoparticles < 100 nm

Scale Bar: 200 nm

NMO-V Stable Charges Enable

Stable CoatingCoated Clay Particle

NMO-V Particles Clay Particle NMO-V Coated Clay

NMO-V

a Strong Lewis Acid (Super acid)

Lewis Acids: Accept lone pairs of electrons

e.g., N, S, O and P

Lewis Bases: Donate lone pairs of electrons

Basis of NMO-V unique properties (?)

Destroys chemicals

• 2-chloroethyl ethyl sulfide, EES,(Mustard Gas Analog)

• dimethyl methylphosphonate, DMMP, (Sarin Gas Analog)

• sulfides, mecaptans and amides

Novel NMO-V Properties

Disrupts cells (oxidizes membranes?)

Novel NMO-V Properties

NM7OApplication: Bacteriacide

.

Bacterial Survival Rate

• Control contained 1 x 108 cells.

• If all cells survived - 1 x 106 cells to grow

on the plate (100 ml sample).

• Only 4 cells (colonies) grew

– the survival rate was 4/1 x 106 or 0.0004%.

Chemistry of Color Change

Mn(VII) Oxide (Violet Color)

Mn(IV) Oxide (Brown/Black Color)

Smart Sensors

Nanotechnology in Textiles

Overall Objectives

• Incorporate Nanophase Mn Oxides (NMO-V) in fibers/fabrics, especially nonwovens

• Study the effect of these additives on processing

• Study the effect of these nano additives on structure, properties and performance of the fabrics

• Evaluate selected applications

Nonwovens Coated with NMO-V

Three Different Nonwovens coated with NMO-V:

A 80gsm needle-punched cotton nonwoven.

A through air bonded cotton/polylactic acid (PLA).

Meltblown polyurethane

Aqueous dispersion of NMO-V on clay particles

Chemicals Coating ProcessDip, Squeeze, and Cure

Delivery Roller

Feed Roller

Trough

Pressure Rollers

Oven

Air Out

Air in

Trough contains NMO-V dispersion in water

Sample

Feed Coated Washed

Basis wt.

gsm

Basis wt.

gsm

Basis wt.

gsm

Cotton needle

punched- 1

dip

79.9 85.25 80.29

6.7% 0.5%

Cotton/PLA

1 dip

80.72 131.3 81.7

62.7% 1.2%

Cotton/PLA

2 dip

80.72 172.7 89.35

113.9% 10.7%

Coating of Nonwovens with NMO-V

Cotton/PLA Before and After NMO-V

Coating (SEM)

Melt Blowing studies

Melt Blowing Studies

• Start with NMO-V master batch (20%) in polypropylene– Dilute to final concentration with:

• MB grade polypropylene (PP)

• Polylactic acid

Melt Blown Samples

• PP Control

• 2% NMO-V in PP

• 5% NMO-V in PP

• 2% NMO-V in PLA/PP

Melt Blown Samples

Melt Blown Samples

Addition of NMO-V does not affect fiber diameter

Melt Blown Fabrics

• Fabrics with fine fibers can be produced

• Properties comparable to that of control

• NMO- V can be incorporated with a variety fabrics and fibers

• Molded into composite structures

– ex: face mask, respirator, body suits, personal protective equipment

• US Patent 8 163 036, Issued April, 2012

Another Approach: Ultrasonic Spray Coating

• Sono-Tek WideTrack System

– Key Abilities and Features

• Atomization of nanofiller solutions allows for precise control of coating at the specified flow rate.

• Spray Width: 2 -24 in.

•Non-clogging ultrasonic nozzle

• Limited overspray and bounce back

Processes

1.Ultra-sonic nozzle to atomize liquid

2.Liquid delivery system

3.Low velocity air system to create a

uniform and repeatable spray

pattern

Sono-Tek WideTrack Ultra-sonic spray system

coupled with Mathis/Coater/Padder/Oven.

Illustration of nozzle and jet block emphasizing

positioning of air jets to control spray width.

Application of Fabrics Treated with NMO-V

NMO-V Coated Non-Woven Fabric being Used to

Polish aTarnished Silver Bowl

NM7O Coated Non-Woven Fabric

Silver Bowl After Treatment with NMO-

V Coated Non-Woven Fabrics

Antimicrobial Proterties

• Algae

– Chlamydomonas reinhardtii

• Bacteria

– Escherichia coli

Algae Study

• Fabrics (cotton, cotton /pla, meltblown; NMO-V treated and control) cut into approximately 0.025 sq. in.

• Inoculated with 200µl of (3 x 10E6 cells/ml) of a three day culture of Chlamydomonas reinhardtii(green algae).

• Samples were incubated in separate sealed petri dishes at 20-25ºC for 24 hrs.

• Individual samples placed into 125ml Erlenmeyer flask containing 50 mls of TAP media, and shaken for three days in full light and at 20-25ºC at 130 rpm.

NMO-V Fabrics Treated with Algae

Bacteria Study

• Cotton fabrics (NMO-V treated and control) cut into approximately 1 cm2 and inoculated with 4000 – 250 cells of overnight culture of E. coli.

• The samples were kept in separate sealed petri dishes stored at 37ºC for 24 hrs.

• Individual samples were placed into tubes with 2 ml water, vortexed and plated on LB agar

– No colonies with 1000 or less cells

– < 2% survival with 2000 cells

– Many colonies with 4000 cells

– Controls all had many colonies

Continuing Antibacterial Studies

• Standardize evaluation procedure

– modified AOAC 2008-05

• Compare to fabrics treated with silver nanoparticles

• Evaluate different bacterial species

– Pseudomonas diminuta

– Staphylococcus aureus

– Bacillus anthracis

Applications of NMO-V Treated Fabrics

• Chem-Biological Safety Suits

• Garments for Military Personnel Actively Engaged in Warfare

• Tarps, Ropes, Tents (marine environments)

• Air filters

• Water Filtration Unit (Cartridges and Membranes)

• Water Treatment

• Hospital bedding

• Sanitary wipes (biological and chemical)

• Wound dressing

• Biofilms (paints)

• Smart sensor (color change)