Consumer Acceptable Surface Modification and Hard Surface

CleanersHydrophilic or Hydrophobic ?

David R. Scheuing

Mona M. Knock

Colloid and Interface Science Group

Clorox Technical Center

NEW HORIZONS 2008

Consumers Want Cleaning Products that - Are efficacious

Are convenient to use, saving time and effort – Wipes

Are pleasant to use – Orange

Preserve or enhance household surfaces, garments

Fall within definite price ranges

Therefore

Innovative Surfactants, Polymers, Additives and Formulations Will Continue to Appear !

981 US patents issued in “Home Cleaning” in 2003

(All US universities =3181, IBM=3457)

Hard Surface Cleaning with RTU Products =

Complex Kinetics

Spraying/wiping occurs within seconds – No washing bath

Applicator chemistry – Polymer and surfactant loss onto paper towels, etc.

Wiping is high shear environment (>1000 s-1)

Soils are spatially heterogeneous

High energy surfaces = glass, porcelain,tiles,aluminum

Lower energy = appliance/plumbing coatings,PVC flooring,poly(styrene) and related ABS plastics

Evaporation of cleaner = evolution of a wide range of surfactant/oil/water phases

Surface Modification Technology Can Deliver

New Consumer Benefits

“Stays Cleaner, Longer” = delay formation of soap scum, hard water spots on sink, shower.

“Easier Next Time Cleaning” = faster, less effort

Delivery from a familiar cleaner format

Trigger sprayer, toilet cleaner liquid, disposable Wipe

Or a novel format –

Disposable head/nonwoven with a tool

Reasonable pricing

Hydrophilic Surface Modification = Approach #1 To Deliver New Benefits

Adsorb very thin (<100 nm) layers of hydrophilic polymers during cleaning process

Polymers that incorporate significant amounts of water molecules in equilibrium with ambient air -

Yield a disordered surface that is Gel-like

Hydrophilic Layers Can Deliver Both –

Soil resistance = poor wetting of household surfaces by greases = lower adhesion energy

Soil release = easier cleaning

Hydrophilic Layers Can Deliver Both –

Soil resistance = poor wetting of household surfaces by greases = lower adhesion energy

Soil release = easier cleaning

Deliver Soil Resistance with Hydrophilic Polymers

LA cos = ( SA – SL) Young – Dupre’

cos = ( SA – SL) / LA cos = 0 (at

=90º) LA = liquid oil/air tension (can measure !) SA = solid/air tension SL = solid/liquid tension

LA of oil is fixed ! To prevent good wetting of the surface with oil, need to decrease the difference term

“Polar” polymers raise SL- surface “resists” non-polar oil !

“Polar” polymer increases , decreasing adhesion

Solid

Liquid Oil

Air

Solid

Air Liquid Oil

Improve Soil Release with Polymer/Water Layers

Reduce Work of Adhesion Under water – Wa = SO – OW – SW

SO = solid/oil OW=oil/water SW=solid/water tensions

OW is fixed and large (40 mN/m)

If SW small or vanishes, the energy change is driven by how large SO gets !

Oil release spontaneous at Wa = 0 !

Adsorbed polymer layers swollen with liquid water (“gels”) affect both “controlled” tensions. Water only “displacement” of oil possible.

Delivery of Polymers from Cleaners – Challenges

Bulk sacrificial films not of interest – poor aesthetics

Polymer must compete with surfactants for surface sites

Polymer must not interfere with detergency

Ideal polymer or mix of polymers will modify glass and plastic surfaces

Polymer adsorption onto emulsified oils, particulate soils, or applicator is a waste

Price/performance always an issue

Fourier Transform Infrared Spectroscopy Can Guide Polymer Selection and Formulation

Attenuated Total Reflectance (ATR) optical rig

Characterize monolayers, sub-monolayers of surfactants, polymers – adsorbed directly on internal reflection element (IRE)

In thin film case (<200 nm) Absorbance ~ layer thickness

Substrate for adsorption = Ge surface (model polar surface) = the IRE ! (500 mm2)

Adsorption time controlled, 5 min typical

Remove solution, rinse with water

(2.5 ml/rinse)

IRE (Ge)Air

Sampling depth, dp= 736 nm at 1650 cm-1

dp = /2 (sin2 n21 2 )1/2

Refractive index = n2 = 1.5

Refractive index = n1= 4.0

n21=n2/n1

Internal Reflection Optics Key To Analysis of Surfaces – Including the IRE Surface Itself !

50 mm

Trough on Horizon rig

Classical multiple IRE

Multiple Reflections Aid Sensitivity with Versatile Horizontal IRE

Ge surface can also bear thin film of a

plastic polymer, i.e., polystyrene

Commercial Optics & Chamber Control Atmosphere Over Adsorbed Layers

Dry Nitrogen/Air Input Trough – 2.5 ml capacity

Examples of Copolymers for Hydrophilic Surface Modification

OH

O

Y

O

OO

X

25

Tristyryl phenol ethoxylate ester of methacrylic acid co - acrylic (or

methacrylic) acid

“Bigfoot” types

Dimethylacrylamide co - acrylic acid

DMA – AA

Monitor Amide & Acid Groups in Spectra of Adsorbed Layers Monitor EO & Acid Groups in

Spectra of Adsorbed Layers

And – Intense H-O-H stretching and bending bands in FT-IR spectra = Water Uptake Monitoring

And – Intense H-O-H stretching and bending bands in FT-IR spectra = Water Uptake Monitoring

DMA co AA stds on Ge from MeOH

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 5 10 15

micrograms applied to IRE

Ab

so

rba

nc

e A

Mid

e I

0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

Ab

so

rba

nc

e C

H3

-N

Amide CH3-N Linear (Amide)

ATR spectra resemble

transmission spectra when film thickness << dp.

DMA-AA Copolymer Takes Up Water from Atmosphere At All Layer Thicknesses

0

.02

.04

.06

.08

.1

.12

4000 3500 3000 2500 2000 1500 1000

Wavenumber (cm-1)

DMA co-AA films on Ge IRE - calibration with cast films

13.3 ug - under nitrogen purge

13.3 ug, approx 35 nm thickness - ambient air

0.133 ug stds, approx 0.35 nm thickness, purge and ambient air

H-O-H

Abs

orba

nce

-.1

-.05

0

.05

.1

1700 1600 1500 1400 1300 1200 1100 1000 900

Not to same scale

13 ug - 35 nm "thick" film under nitrogen purge

0.133 ug - 0.35 nm "thin" film under purge

Thick film - ambient air

Thin film ambient air

Amide I and H-O-H deform.

COOH

DMA co-AA films on Ge IRE - calibration with cast films

CH3-N

Shifts in Amide I Consistent with Hydration in Air – Leverage Literature on Proteins for Details

Wavenumber (cm-1)

Abs

orba

nce

Reversible Water Uptake - Blanks vs. minimum DMA

co-AA 0.035 ug/cm2 (0.35 nm thickness)

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

Purgeblank

In air blankimmed

In air blank5 min

#2 Purgeblank

#2 Purgeblank 5 min

0.035

Ab

so

rba

nc

e

Amide +Water H-O-H

DMA co-AA 3.57 ug/cm2 on Ge (35.7 nm thickness) - Reversible Water Uptake

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Purge1

In airimmed

In air 5min

Purge2

#2 Inair

immed

#2 Inair 5min

Purge3

#3 Inair

immed

#3 Inair 5min

Ab

so

rba

nc

e

Amide + Water H-O-H

DMA co-AA on Ge - Water Uptake at 5 min in Air -

Effect of Polymer weight - ug/cm2

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0, blank 0.035 3.57 14.24 49.06

Ab

so

rba

nc

e

H-O-H

Water uptake increases with amount of polymer present. None of these layers are visible to the

eye !

Performance of Hydrophilic Polymer Layers – FT-IR Also Useful

Example – Bathroom Cleaning Formulations

Resistance to build-up of soap scum desired

Track soap scum formation via several FT-IR protocols

• Multiple Exposure

• Kinetic Exposure

Interactions of Hydrophilic Polymer Layers with Soaps

Sodium laurate = model soap

Phase behavior known – “soluble” at ambient temperature

• CMC = 20mM, pH > 8.5, T>23 C

• Forms crystal structures, adsorbed layers, etc. similar to longer chain analogs

C14,C16,C18 saturated acids

• Similar phase behavior, solubility, but at higher temperatures = less convenient

Oleate (cis 9,11 octadecenoate) soluble at ambient T

Use 1mM NaLaurate exposure to distinguish performance of different polymers

Multiple Exposure Protocol – Deliver an adsorbed polymer layer or product.

Expose to NaLaurate 5 min, then vacuum off solution

Dry under purge 1 min. Record spectrum

Do four successive exposures.

Then start rinse study. One “rinse” = fill trough with water, then vacuum off.

Kinetic Exposure Protocol Deliver adsorbed polymer layer

Fill trough with 1mM NaLaurate. Record spectrum every 2 minutes for 12 minutes

Vacuum off NaL, record spectrum

Fill trough with water. Record spectrum every 2 minutes during “desorption”

0

.2

.4

.6

.8

4000 3500 3000 2500 2000 1500 1000

Solid Na Laurate reference - 20 ul of 100mM solution dried on Ge IRE

CH2 str. asymm, symm

COO - asymm

Wavenumber (cm-1)

Abs

orba

nce

.1

.2

.3

.4

.5

.6

.7

1600 1500 1400 1300 1200 1100 1000

Solid Na Laurate reference - 20 ul of 100mM solution dried on Ge IRECOO - asymmetric str

CH2 defCH2-C=O

COO- symm str

CH2 wagging

Wavenumber (cm-1)

Abs

orba

nce

Net Scum Adsorption Depends on Exposure/Rinse Protocol

0

.05

.1

.15

4000 3500 3000 2500 2000 1500 1000

Ge IRE Exposed to 1 mM NaLaurate - "Soap Scum" Buildup Test

Run 1 no rinse

Run 1 12x water rinse

Run 1 24x water rinse

Run 2 no rinse

Run 2 12x water rinse

Run 2 24x water rinse

Wavenumber (cm-1)

Abs

orba

nce

0

.02

.04

.06

.08

.1

1800 1700 1600 1500 1400 1300 1200 1100 1000 900

Ge IRE Exposed to 1 mM NaLaurate - "Soap Scum" Buildup Test

Na Laurate dried reference from 100 mM solution "bulk film"

Lauric acid adsorbed from 1 mM NaLaurate solution pH 8.5

COO- asymm

COOH

CH2 def

C-OH acid

no rinse

12x rinse

24x rinse

Crystalline Lauric Acid Adsorbs from Dilute Solutions

Wavenumber (cm-1)

Abs

orba

nce

.02

.04

.06

.08

3000 2950 2900 2850

1mM NaLaurate pH 7.8 Adsorbing on Ge

12 min

Final - dry

10 min

8 min

All to same scaleLiquid Water subtracted (0-12 min)

6 min

4 min

2 min

0 min

Lauric Acid Adsorbs, Then Crystallizes on Surface – Kinetic Run Spectra, Under Water

Wavenumber (cm-1)

Abs

orba

nce

-.02

0

.02

.04

1700 1600 1500 1400 1300 1200 1100

1mM NaLaurate pH 7.8 Adsorbing on Ge

12 min

Final - dry

10 min

8 min

All to same scaleLiquid Water subtracted (0-12 min)

6 min

4 min

2 min

0 min

Wavenumber (cm-1)

Abs

orba

nce

0

.02

.04

.06

.08

.1

2980 2960 2940 2920 2900 2880 2860 2840 2820

Ge Exposed to 1mM NaLaurate Effect of pH

pH 7.8

pH 6.5

pH 8.8

pH 9.8

Not to same scaleDried Layers in Air

Adsorbed Species Depends on pH

Wavenumber (cm-1)

Abs

orba

nce

Laurate Adsorbs Only from high pH Monomeric Solutions

-.02

0

.02

.04

.06

1700 1600 1500 1400 1300 1200 1100 1000 900

Ge Exposed to 1mM NaLaurate Effect of pH

pH 7.8

pH 6.5

pH 8.8

pH 9.8

Not to same scale

Dried Layers in Air

Wavenumber (cm-1)

Abs

orba

nce

Exposure to 1 mM NaLaurate indicates -

Lauric acid is adsorbed, not soap, at bulk conc. < cmc and “low” pH

Consistent with early FT-IR studies of sodium laurate on Ge *

Net amount of acid adsorbed depends on number of rinses between exposures

Real world soiling of surfaces with fatty acids and soaps begins at very low concentrations during rinsing of basins, showers, and wiping of countertops.

Soap scum starts with a hydrophobic layer that is too thin to see. A mono-layer is all you need to change the nature of the surface.

Soap scum starts with a hydrophobic layer that is too thin to see. A mono-layer is all you need to change the nature of the surface.

* Takenaka,T. Higashiyama,T. J.Phys.Chem. 1974,78,9

Ge Surface with Polymers Exposed to 1 mM NaLaurate Rinsing of Lauric Acid as Evaluated by CH2 Band

0

0.05

0.1

0.15

0.2

0.25

0.3

Run1

Run2

Run3

Run4

12xrinse

24x 36x 48x 60x 72x 84x 96x

Ab

so

rba

nc

e, C

H2

La

uri

c A

cid

Control Control 2 DMA:AA Amphoteric Copolymer

Significant Differences Between Anionic and Amphoteric Polymers in Scum Prevention

Polymers on Ge (0.5%, 5 min ads time) Exposed to 1mM NaLaurate

0

0.02

0.04

0.06

0.08

0.1

0.12

0 2 4 6 8 10 12

time, mins

Ab

so

rba

nc

e, C

H2

la

uri

c a

cid

No polymer Polymer Mix A DMA-AA Polymer B Polymer C

Kinetic Protocol Probes Resistance of DMA -AA and Others to Lauric Acid Adsorption

No Polymer

DMA-AA

Polystyrene Surfaces Rendered Hydrophilic via Adsorbed Layers of “Bigfoot” co – AA Polymers

0

.001

.002

.003

.004

.005

.006

.007

1800 1700 1600 1500 1400 1300 1200 1100 1000

all to same scale

C=O, ester,acid

Under purge, Cycles 1,2,3

Under Water, Cycles 1,2,3ps

ps

ps

C-O-C, EO groups

Copolymer layer is unchanged after 40x rinses/3 water immersions. Band shifts show EO chains are not crystalline and readily hydrate !

Wavenumber (cm-1)

Abs

orba

nce

Polymers on Polystyrene Exposed to 1mM NaLaurate

0

0.02

0.04

0.06

0.08

0.1

0.12

0 2 4 6 8 10 12

Time (min)

Ab

sorb

ance

, CH

2 L

auri

c ac

id

Bigfoot copolymer run1 Bigfoot run2 Polymer B No polymer

Scum Resistance of Polymers on Polystyrene/Ge Screened Via FT-IR

Macroscopic Perfomance – Black Acrylic Exposed to Bar Soap & Hard Water – 5 Cycles

Original Product Contact Time = 90 seconds, Then First Soap Exposure

Untreated Treated

Macroscopic Perfomance – Black Acrylic Exposed to Bar Soap & Hard Water – 10 Cycles

Untreated Treated

Untreated Treated

Macroscopic Perfomance – Black Acrylic Exposed to Bar Soap & Hard Water – 15 Cycles

Summary – Hydrophilic Approach

Adsorbed monolayers of hydrophilic polymers can modify surfaces to deliver consumer benefits - “Easier Cleaning” and “Stays Cleaner, Longer”

Uptake of atmospheric water into adsorbed layers is reversible and essential to performance

Control of the interactions of soluble soaps with surfaces needed in bathroom applications

Soap – surface interactions can be engineered with appropriate polymers

FT-IR is routinely used in evaluation of –

Amounts of polymer adsorbed and water uptake

Interaction of the polymer with oils, soaps, etc.

Approach #2 – Hydrophobic/Oleophobic Modification

Oleophobic = Deliver Adsorbed Layers of Anionic Fluorosurfactant/Cationic Polymer Complexes

Most useful = Reduced adhesion of oily soils

Hydrophobic = Ordinary Anionic Surfactant/Cationic Polymer Complexes

Formulate in a RTU cleaner format

Surfactant system = Mixed Nonionic/Anionic micelles

Cationic polymer – Example DADMAC

Stepping Back a Moment - -

Does everyone agree on what hydrophobic means ??

Surface Modification for Soil-Repellancy: Defining Success

High Contact Angle: Oil, Water

Slide-off (roll-off, low hysteresis): Oil, Water

Young’s equation: S = SL + L cos

S

L

SL

solid

air

Contact Angles and Sliding Droplets – Common Truisms

Not always true!

Common advancing / receding

contact angle measurement

θθ

smallersurface free energylarger

worseadhesivenessbetter

worsewettabilitybetter

largercontact anglesmaller

Drop Shape Analysis

Equilibrium sessile drop contact angles obtained with Krüss DSA-10L with tilting table feature

Test fluids•Ultrapure H2O•Anhydrous C16

For non-pinned drops:•Sliding angle, α•θA and θR

air

A

L advancing (A)

L receding (R)

Rsolid

α

Hysteresis – the basics

Liquid-solid adhesive bond created during spreading

Homogeneous smooth surface may exhibit less hysteresis

Recession of contact line can break adhesive bond.

R > 0: liquid debonds from solid; adhesive failure.

R 0: liquid – solid adhesion > cohesive strength of liquid; drop ruptures and leaves a trail = sheeting

Hysteresis: = A – R for liquid on surface

θa

θrmg sin α

mg cos α

mgα

More on Hysteresis

Hysteresis is particularly detrimental to hydrophobic surfaces.

For minimum surface tilt of , a droplet of surface tension LV with mass, m, and width, w, will spontaneously move:

m g (sin ) / w = LV (cos R – cos A)

Difference between A & R (hysteresis) is more important

to hydrophobicity than the absolute values of the contact angles!

DROPTOPVIEW

Only water molecules on 3-phase contact line must move for drop to move.

Only water molecules on 3-phase contact line must move for drop to move.

Hydrophobicity and Hysteresis

Pinned drops with any not very useful !

Sliding drops are ideal to deliver real consumer benefits !

Control of the composition and uniformity of the adsorbed layers is critical !

Both Fluorosurfactants Soluble @ 1% in Water – AT-1002 Has Fewer, More Hydrophobic Tines than PF 156

Polyfox PF-156A from Omnova

Polyfox AT-1002 (experimental)

C-F stretching yields intense IR

absorbance

Thomas, R.R., et. al, Langmuir, 2002, 18, 5933-5938

Cationic Polymer = pDADMAC

pDADMAC Binding To Micelles Depends on Micelle Charge and Electrolyte Mixed Nonionic/Ionic micelles interacting with a

Polyelectrolyte (opposite charge)

Micelle Charge Defined by “Y”

Y = [Ionic]

[Ionic] + [Nonionic]

Anionic Fluorinated

Oxetane

NH4+Nonionic

Mixed Anionic Fluoro /

Surfonic micelle

+

+

+

+

+++

+

+

+++

+

+

+

++ +

+

+

+

+

++

+

+ ++

+

+ +

+

+

+

+

Cl-

A “critical charge” (crit) required for polymer-micelle binding !!

crit ~ b / q= Debye-Huckel parameter, (nm-1)

q = polymer charge spacing

b varies with micelle shape, polymer type

Binding of micelles required to form coacervate and precipitate

Precipitate = polymer/surfactant phase, solid, no water

Coacervate = polymer/surfactant – rich phase, with water

Critical MW/size & near neutral overall charge

Intrapolymer complexes yield interpolymer complexes

Complexes reject some water, settle (“bottom” phase)

Coacervation depends on

Micelle Charge (“Y”)

Polymer MW

Screening” of charges by electrolyte (Debye length)

Critical [Polymer] Needed To Form Large Complexes for Coacervation

System = p(DADMAC) / Triton X-100 / SDS

Coacervate Formed at > 0.01% DADMAC, Aggregates

> 45 nm radius

Complexes But No Coacervates – Aggregates Too Small !

Intrapolymer Complexes Only

Phase Behavior Variables = [DADMAC] & Ratio of Anionic/Cationic groups = R

Systems Made on 20 ml Scale – Rapid/Easy Mixing

Nonionic = Surfonic L12-8, Constant @ 2 wt% (39 mM)

Poly(DADMAC) Level Varied -

@ Low = 0.3 mM (50 ppm)

@ High = 3.0 mM (500 ppm)

Anionic Fluoro-oxetane Varied -

Cover R= Anionic/Cationic Equivalents – 0.04 to 8.0

At low [DADMAC] = [Oxetane] = 0.001 to 0.25 %

At high [DADMAC] = [Oxetane] = 0.01 to 2.2%

Surface Compositions Assessed With FT-IR

How Does Modification of Surfaces (within 5 minutes) Depend on Location in Phase Boundary Diagram ?

Poly(DADMAC) Adsorbed on Ge – Adequate Detection Limit < 0.5 mg/m2

Dried, Rinsed

Freely Adsorbed from 3 mM Solution

Dried Reference,

Not to same scale

Detection Limit (CH3-N+) < 0.3 mAU

Intense Bands Available for Detection of Fluorinated Oxetanes in Adsorbed Layers

S-O Asymm. Stretch

SDS, hydrated

S-O Symm. Stretch

Bands due to Coupled C-F, S-O, C-O-C stretching

C2F5 - oxetane

C4F9 - oxetane

PF156 (C2F5 chains) Systems Yield Coacervates but No Precipitates

PF 156/Surfonic Interactions with 3.0 mM DADMAC

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5 6 7 8

R= Anionic/Cationic Equivalents

Na

Cl,

M

clr 2, clr+coacervate

PF 156/Surfonic Interactions with 3.0 mM DADMAC

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.05 0.1 0.15 0.2 0.25 0.3

Y, Mole Fraction Anionic in Micelle

Na

Cl,

M

clr 2, clr+coacervate

Net Cationic Complexes

Net Anionic Complexes

AT 1002 (C4F9) Systems Show Collision of Precipitate and Coacervate Regions. How does R Affect Surface Modification ?

AT 1002/Surfonic Interactions with 3.0 mM

DADMAC

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.1 0.2

Y, Mole Fraction Anionic

NaC

l, M

clr 2, clr+ coacervate

2, clr+ppt 2, coacervate+ppt

AT 1002/Surfonic Interactions with 3.0 mM

DADMAC

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5 6 7 8

R=Anionic/Cationic Equivalents

NaC

l, M

clr 2, clr+ coacervate

2, clr+ppt 2, coacervate+ppt

AT 1002/ 3.0 mM DADMAC – Adsorption Increases Near Coacervate Boundary For Net Cationic Complexes @ R < 1, High [Salt], 2-Phase Systems Reduce Adsorption

0

0.002

0.004

0.006

0.008

0.01

R=0.19

3 0 M

NaCl

R=0.37

6 0 M

NaCl

R=1.99

7 0 M

NaCl

R=4.0

0 M

NaC

l

R=8.0

0 M

NaC

l

R=0.19

5 0.1

M N

aCl

R=0.39

2 0.1

M N

aCl

R=0.58

2 0.1

M N

aCl

R=4.0

0.1

M N

aCl

R=0.09

9 0.5

M N

aCl

R=0.21

7 0.5

M N

aCl

R=0.42

0.5

M N

aCl

R=0.98

9 0.5

M N

aCl

R=7.94

0.5

M N

aCl

Ab

sorb

ance

DADMAC CH3-N C-F @ 1236 C-F @ 1130

Adsorption conditions = 5 minutes’

exposure of Ge IRE, Then Rinsed 50x

with water

No Drying Step !

At Low [DADMAC], Coacervate Region Reduced. How Does Adsorption Change with R?

AT 1002/Surfonic Interactions with 0.3 mM DADMAC

0

0.1

0.2

0.3

0.4

0.5

0.6

0 1 2 3 4 5 6 7 8

Equivalents, Anionic/Cationic

NaC

l, M

clr 2, clr + coacervate 2, clr+ppt

AT 1002/Surfonic Interactions with 0.3 mM DADMAC

0

0.1

0.2

0.3

0.4

0.5

0.6

0 0.01 0.02 0.03

Y, Mole Fraction Anionic

Na

Cl,

M

clr 2, clr + coacervate 2, clr+ppt

AT1002 at Low [DADMAC] = Maximum Adsorption Near Boundaries, But High [Salt], Net Anionic Complexes Inhibit Adsorption

0

0.002

0.004

0.006

0.008

0.01

R=0.40

0 M

NaC

l

R=0.98

, 0 M

NaC

l

R=7.86

0 M

NaC

l

R=0.40

0.1

M N

aCl

R=0.94

, 0.1

M N

aCl

R=1.70

0.1

M N

aCl

R=0.40

0.5

M N

aCl

R=0.98

, 0.5

M N

aCl

R=1.86

0.5

M N

aCl

Ab

sorb

ance

DADMAC CH3-N C-F 1236 C-F 1136Equal Fluorosurfactant

Adsorption at 1/10 the Level - $$

Surfonic L12-8 is Absent From Adsorbed Layers

Reference Spectrum Surfonic L12-8 Dried on

Ge

CH2 Stretching of Methylenes

in Tail

CH2 Stretching of CH2-O

C-O-C Stretching

C-F, S-O Stretching

CH3-N+

Adsorbed Layer, R=0.94

Adsorbed Layer, R=1.70

Adsorbed Layer Spectra – AT 1002/Surfonic @ low DADMAC

Not to same scale

Oil Repellancy with Sliding Drops is Possible via AT-1002 Complexes, but not with Largest Contact Angle !

3 mM pDADMAC0.3 mM pDADMAC

0.0 0.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.50

10

20

30

40

50

60

70

C16 Theta 0 M NaCl

C16 Theta 0.1 M NaCl

C16 Theta 0.5 M NaCl

C16 Theta(A) 0 M NaCl

C16 Theta(R) 0 M NaCl

C16 Theta(A) 0.1 M NaCl

C16 Theta(R) 0.1 M NaCl

C16 Theta(A) 0.5 M NaCl

C16 Theta(R) 0.5 M NaCl

Con

tact

Ang

le o

f H

exad

ecan

e in

deg

rees

[PF1002] in mM

Water Repellancy Possible with PF AT-1002 Complexes, But Many Drops are Pinned !

3 mM pDADMAC0.3 mM pDADMAC

0.0 0.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.50

10

20

30

40

50

60

70

80

90

100

W Theta 0 M NaCl W Theta 0.1 M NaCl W Theta 0.5 M NaCl W Theta(A) 0 M NaCl W Theta(R) 0 M NaCl W Theta(A) 0.1 M NaCl W Theta(R) 0.1 M NaCl W Theta(A) 0.5 M NaCl W Theta(R) 0.5 M NaCl

Con

tact

Ang

le o

f W

ater

in d

egre

es

[PF1002] in mM

Proximity to Coacervate Drives Adsorption – Factors

PE with bound micelles yield low charge density, thick layers.

Micelles solubilize PE segments = More loops and tails of PE = More flexible PE chains

Surf. Monomer - micelle exchange remains fast

Oxetane - DADMAC – Surface becomes hydrophobic = Significant tail exposure

Adsorbed Layers of PEs Almost Never at Equilibrium++

++

+

+++

+

+

+++

++

+

++ +

+

+

+

++

+

+

+ ++

+

+ +

+

+

+

+

Mixed anionic /nonionic micelle

Anionic surf

Na+ Cl-

Nonionic

- - - - - -- - - -+ +

+

+

+ ++ +

+ ++ +

++

+++

++

Significant Lateral

Interactions of Surfactants

Conclusions – Hydrophobic Approach

Complete drop slide-off demonstrates water- and/or oil- repellancy

High contact angles (~ 90°) do not necessarily confer repellancy

Higher complex concentrations produce repellancy at short adsorption times (5 minutes)

Salt concentrations > 0.1 M NaCl are detrimental to repellancy

PF AT-1002 complexes at 3 mM pDADMAC and 0 – 0.1 M NaCl are able to achieve both water- and oil- repellancy

Conclusions – Hydrophobic Approach

Control of Complex Size & Composition Critical

Adsorption Kinetics Important (5 minutes or Hours?)

Understanding structures formed important – cost$

Oleophobic Modification Performance Correlates With Fluorosurfactant Adsorption !

AT 1002 (C4F9 groups) Far Superior

Best performers are Compositions Near Coacervate Boundary

FT-IR Useful for Monitoring Composition of Adsorbed Layers

Final Thoughts

Hydrophilic Approach May Be Easier Depends on Anticipated Soil Types – Beware Soaps !

Hydrophobic/Oleophobic Modification Possible ! Understanding of Coacervate Boundaries Helps !

Adjust Compositions to Avoid Pinning Oil & Water Drops

Assess Performance via Drop Hysterisis

“Targeted” Use of Expensive Materials

Consumer-perceivable benefits from invisible (thin) layers ! RTU Cleaning Formulations Possible – One Step

Industrial/Professional Products Possible Labor Reduction in Janitorial Products – but Familiar Formats

Aesthetic Improvements of Surfaces Encountered By Public

Thanks !

Clorox Management

Consumer Specialty Products Association

Mona Knock

You – The Audience & Consumer !!!