Silicone Nanocoatings electrical properties, anti- adhesion and fire

resistance Pr. Philippe DUBOIS

Center of Innovation and Research in Materials and Polymers

MATERIA NOVA Research Center & UNIVERSITY of MONS

Place du Parc 20, 7000 Mons Belgium

Philippe.Dubois@umons.ac.be

http://morris.umons.ac.be/CIRMAP

NANORA seminar 'Using nanotechnologies to optimise your coatings, SIRRIS, Seraing, January 15th, 2015

Nanocomposites : Definition and Generalities

Nanocomposite : heterophasic system where the dispersed phase

(of a different nature than the continuous phase)

has at least one of its dimensions in the order of a few nanometers

3 nanodimensions : nanosized "isotropic" particles - metallic : Ag, ZnO, metal oxides, - inorganic : POSS, CdS, SiO2, Ca/Mg(OH)2, ferrites, - organic : carbon black, 2 nanodimensions : nanotubes, nanofibers and nanowhiskers - inorganic : sepiolite, halloysites - organic : carbon nanotubes/nanofibers, cellulose nanowhiskers and microfibers, 1 nanodimension : nanolayers - organic : exfoliated graphite, cristalline starch nanoplatelets, - inorganic : layered double hydroxides, layered silicates/clays,

Continuous phase : metal, ceramic, polymer,

Dispersed phase : nanofiller(s)

~ 1-2 nm

Few microns

Single-wall nanotubes

~ 2 - 50 nm

TEM images of various MWNTs

Multi-wall nanotubes

Carbon Nanotubes

Polymer Nanocomposites : Definition

Heterophasic polymer-based materials

where the dispersed phase, i.e. nanofiller(s), has

at least one of its three dimensions

in the order of a few nanometers

However,

-ALL nanofillers do form aggregates and even larger (m-size) agglomerates

- At best, in polymer matrices, nanofiller dispersion/individualization can be reached at filler content of max. 10 wt% (depending on filler geometry and shape factor)

from m-size to >>> thousands aggregates individual nanoparticles

Nanocomposites : the Processing Challenge

Polymer

Huge polymer-nanofiller interface

Synthetic MWNTs as produced via CCVD

NC 7000 (CNTs) from Nanocyl 0.1 10 m

10 nm

Characterization

Property Unit Value Method of Measurement

Average diameter

Average Length

Carbon Purity

Metal Oxide (impurity)

Amorphous Carbon &

Carbon Shells (impurity)

Surface area

nanometers

microns

% %

%

m2/g

9.5

1.5

90

10

Not detectable

250-300

TEM

TEM

TGA

TGA

HRTEM

BET

Studied silicone : hydrosilylation curing Sylgard 184 PDMS*

Si O Si O SiH

p

Si O m

Si O Si O Sip

SiO

m +

Optimized reaction conditions (time, T(C), molar ratio, catalyst, etc.) :

highly cross-linked & stable

PDMS networks 100-500m thick PDMS coatings

PART A

PART B

Pt catalyst

* From Dow Corning

Comp. 1 (Nature-%)

Comp. 2 (Nature -%)

Comp. 3 (Nature-%)

Other components

Dynamic viscosity

Part A (10 parts)

Vinyl-ended PDMS : SFD 117

67%

VQM 1 (2% vinyl)

31%

Pt Catalyst

0.14%

Volatile cyclics and

low MW silicone (1.5%)

and xylne (0.7%)

4817 cP

Part B

(1 part)

Si-H containing

PDMS (0.76% H) :

MDD(H) 60%

SFD 117

39%

Inhibitor

1% -

89.1 cP

Sylgard 184 resin : hydrosilylation curing resin

CH2 CH ( CH2)n ( Si O ) 434Si ( CH2)2n CH CH2

SFD 117 :

Si O Si O

Me Me

Me H

( ) ( )MDD(H) : SiSi O

Si O Si O Si

Me

O

O

SiO

Si

O

: VQM 1

Si

SiO

Si

O SiO

O

Inhibitor :

Production of nanofiller-modified silicone systems

mixing for 2h (by mechanical stirring at

1200 rpm, r.t.) of part A + nanofillers Addition of part B, mixing, casting and

then curing for min. 6h.

Viscosity evolution of CNTs-filled PDMS (part A) with shear rate

- Huge increase of the viscosity at lower shear rate - Rheothinning effect !!

Moreira L. et al., Macromolecules, 43, 1467(2010)

Viscosity evolution of CNTs-filled PDMS with shear rate

In other words : high interests of MWCNTs for coating application Easiness of the application process Possibility to brush-paint the PDMS formulation (before cross-linking reaction) in every position (e.g. floor, walls, ceiling)

Remarkable affinity between MWNTs and PDMS

OSi

OSi

OSi

OSi

O

Me MeMe MeMe Me MeMe

Si Si Si Si OH OH O O

Silica

PDMS

fully confirmed by theoretical modeling

Crosslinked PDMS + 0.5

wt% MWNTs

CNT-filled Silicone : ELECTRICAL CONDUCTIVITY

-14

-12

-10

-8

-6

-4

-2

00 0,5 1 1,5 2 2,5 3

Filler content (wt%)

LOG

Con

duct

ivity

(S.c

m-1

)

PDMS + PMWNTs 7000 (from NANOCYL)

2-point method

GOOD CONDUCTIVITY AT LOW FILLER CONTENT

NANOCYL (Belgium) : Commercial STATICYL Grade

Tests of different methods to apply the (nano)coating

By brush By injection

By spray on different supports, incl. foams

The core of the material (e.g. foam) is

not modified

NANOCYL (Belgium) : Commercial Grade NC7500 Courtesy from Nanocyl

CNT-filled Silicone : FIRE RESISTANCE BEHAVIOR

Flame-resistance testing

Aluminum 4 mm

Recorded temperature

vs. time

Alkoxysilane primer

(CNTs-filled) silicone

~2-4 mm

~ 1100C

>60 kW/m2

Adaptation of ISO 2685 test

Flame-resistance testing : coating thickness ~2 mm (readily applied by brush painting)

Exceptional resistance to fire !

0

50

100

150

200

250

300

350

0 10 20 30 40 50 60 70 80 90

Time (min)

Tem

pera

ture

(C

)

0,1% CN7500 (1100C)

0,25 % CN7500 (1100C)

Non coated Aluminum

Unfilled Silicone

Why such a flame barrier behavior ?

Fine CNTs dispersion and interconnectivity within cross-linked silicone

- Better dissipation of heat flow all over the coated surface - Higher char cohesion and

mechanical performances

NANOCYL (Belgium) : THERMOCYL Grade

Protection of PU foams :

Without THERMOCYL :

Burns quickly with dripping

With THERMOCYL :

No burning (even after few minutes)

Courtesy from Nanocyl

Biofouling of a ship hull by barnacles (photo courtesy International Paint Ltd)

Silicone Carbon Nanotube Nanocomposites :

anti-biofouling properties ?

Biofouling : economic and environmental costs

Just for shipping : Biofouling causes increase in frictional drag on ships >>>>> Antifouling estimated annual

savings of 20 billion! (~ 120 million tons fuel/year) >>>>> Antifouling estimated annual CO2

reduction : 384 million tons CO2

Biofouling is the accumulation of unwanted microorganisms, plants and animals on man-made surfaces-

such as those exposed to the marine environment - Fouling has been controlled traditionally by antifouling paints that contain biocides (i.e. compounds that are toxic to the organisms; tin or copper-based biocides). - But, regulations now require that antifouling paints must not cause adverse effects in the environment and the search is on for more environmentally friendly ways of deterring marine life from hitching a ride on the hull of a vessel

As checked at two levels : - Lab scale : on Alga Ulva spores, barnacles (cyprids) - field tests : immersion in sea water (on the raft)

* Coll. with University of Birminghan, University of Newcastle and TNO

(AMBIO Project; 6th FP of EU)

CNT-filled silicone coatings : Anti-biofouling behavior

Carbon nanotube-filled PDMS coatings

After 4 months of field trials

Barnacle evaluation: 24h settlement assays with Barnacle Cyprids. Effect of MWNTs relative content

0

20

40

60

80

100

120

140

160

Glass UnfilledPDMS

0.05 wt %,MWCNTs

0.3 wt %,MWCNTs

0.5 wt %,MWCNTs

1 wt %,MWCNTs

2.5 wt %,MWCNTs m

ean

perc

en

tag

e s

ett

lem

en

t co

mp

are

d t

o t

he g

lass

st

an

dard

(%

)

Srie1

Equivocal pass line Outright pass line

Important effect of CNTs on the settlement behavior, even well under the already performant

(unfilled) silicone

Removal* of AlgaUlva spores from MWCNTs-based coatings (*by exposure to a 52 Pa wall shear stress in a water-channel apparatus)

A. Beigbeder et al., J. Nanosci. Nanotechnol., 10, 2972(2010)

Surface characterisation of CNTs- filled PDMS Atomic Force Microscopy

AFM images of (A) unfilled PDMS and (B) coatings filled with 0.1 wt% CNTs after one day immersion in water.

Upon MWNTs addition and after immersion in water, the flat surface is transformed into a nanostructured surface and consequently accounts

for the recorded enhancement in terms of fouling release properties.

B Z = 20 nm Z = 30 nm Z = 30 nm

(A) unfilled PDMS (B) PDMS filled with 0.1 wt% CNTs

3D AFM topographic profiles of MWCNT-filled silicone coatings - after 1 and 6 days of immersion (a &,b) as observed in air, - and after 6 days of immersion (c) as observed directly in water

Nanostructuration of the coatings upon immersion in water.

0.1 wt% MWCNTS

1 day 6 days 6 days

Observations in air Obs. in water

A. Beigbeder et al., J. Nanostruct. Polym. Nanocomp. 5/2, 37 (2009)

Carbon nanotube-filled PDMS coatings

Carbon nanotube-filled PDMS coatings Biocyl/Liocyl TopCoat on Nadine super-tanker :

Carbon nanotube-reinforced PDMS Conclusions : Possibility to strongly improve rheological and processing/applicability properties

high interfacial affinity >>> fine MWNTs dispersion >>>> - low percolation threshold (~ < 0.2wt%) Fine tuning of both electrical and thermal properties without any change of the bulk properties.

Remarkable flame resistance behavior

Improve of the foul release properties against alga foulers and macrofoulers via a lotus-like effect (nanorugosity) ?

BIOCYL

Acknowledgements

AMBIO partners Pr. Callows group, University of Birminghan (biological evaluations)

Pr. Clares group, University of Newcasttle (biological evaluations)

TNO (biological evaluations)

BASF (AFM in sea water and dynamic contact angles)

Nanocyl (MWCNTs supplier) : F. LUIZI, M. CLAES, D. BONDUEL

UMONS-CIRMAP Alexandre BEIGBEDER

Philippe DEGEE

Rosica MINCHEVA

Myriam DEVALKENAERE

Joao BOMFIM

UMONS-CIRMAP (dynamic molecular simulation) Mathieu LINARES

David BELJONNE

Roberto LAZZARONI

European Framework Program

Thank you for your attention !

Slide Number 1Slide Number 2Slide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Production of nanofiller-modified silicone systemsSlide Number 10Slide Number 11Slide Number 12Remarkable affinity between MWNTs and PDMSSlide Number 14Slide Number 15Slide Number 16CNT-filled Silicone : FIRE RESISTANCE BEHAVIORFlame-resistance testingFlame-resistance testing : coating thickness ~2 mm (readily applied by brush painting)Why such a flame barrier behavior ?Slide Number 21Slide Number 22Biofouling : economic and environmental costsSlide Number 24CNT-filled silicone coatings : Anti-biofouling behaviorSlide Number 26Slide Number 27Slide Number 28Slide Number 29Slide Number 30Slide Number 31Slide Number 32Slide Number 33Slide Number 34Slide Number 35