new horizons conference consumer specialty products association 2008 - scheuing
DESCRIPTION
Invited talk presented at the 2008 New Horizons Conference of the Consumer Specialty Products Association. Addresses aspects of the modification of household surfaces - chemical type, performance, and characterization.TRANSCRIPT
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 !!!