New Generation of Functional Cellulose Fibre Based Packaging Materials for Sustainability

FP7 - People - 2011

ITN Marie Curie Initial Training Network (ITN) Project Number 290098

Using nanoscale computational

models to probe the barrier

properties of dry, clay-based

coatings

ESR2 - Nikita Siminel

Materials and Engineering Research Institute

Sheffield Hallam University

Prof Chris Breen

Prof Doug Cleaver

Dr Francis Clegg

Sustainable coatings under scrutiny

Water Vapour Transmission Rates (WVTR), g/m2.day 100 µm

Double coating layer

100 µm

Board substrate

"bad" clay

"good" clay

Within the SUSTAINPACK and FLEXPAKRENEW

projects, a particular combination of bio-polymer

(starch), clay and plasticiser which transforms

paper into an effective barrier material has been

identified. This concept is being further developed

under the CaiLar® name within the spin-out

company BarrCoat AB (www.barrcoat.AB).

Lars Järnström Caisa Andersson

Sustainable coatings under scrutiny

Water Vapour Transmission Rates (WVTR), g/m2.day 100 µm

Double coating layer

100 µm

Board substrate

"bad" clay

"good" clay

How can modelling

improve our

understanding of

barrier properties of

sustainable

packaging?

Sustainable coatings under scrutiny

100 µm

Double coating layer

100 µm

Board substrate

× Use of small, nanoscale computational models to predict macroscale parameters of clay-

composites

× Swelling behaviour of clays in water

+ Simulation data shows excellent match to experimental findings

× Swelling behaviour of clays in plasticiser

+ Simulation mimics experimental data in a finest way

+ And gives level of information inaccessible through use of experimental techniques

× Direct link between clay layer charge, clay charge location and plasticiser’s

conformations in the composite

+ Simulation tells us how do conformations of plasticiser depend on structure and type of used

clay

Key Outcomes

Computational models - Clay

Clay (Na+ – Montmorillonite) Na+

Al3+

Si4+

Mg2+

O2-

H+ * Cygan et al., J. Phys. Chem. B (2004), 108(4): 1255-1266

Full-atom description

CLAYFF* force field

Charge location is distributed

between tetrahedral (Th) and

octahedral (Oh) sheets

85.0 meq 104.4 meq 113.1 meq

[ 001

]

[010]

Tetrahedral

Octahedral

Tetrahedral

41 Å

Small, but still

capable

H – (O-CH2-CH2)4 – OH

Mw = 194.23 g∙mol-1

PEG200

Starch (amylose) bio-polymer

Poly(ethylene glycol) plasticiser

14.3

Å

Mw = 830.42 g∙mol-1

AML

Full-atom description

Modified PCFF* force field

Widely applicable for organic molecules

* Maple et al., J. Comput. Chem. (1994) 15: 162

Computational models

20.8

Å

10.5 Å

Reasons for

Computational Physics

Current experimental

analysis cannot tell us how

mobile species (starch,

plasticiser) are distributed

between the gallery and the

matrix

Mobile species

in the gallery

Computer simulation will

help to establish how starch

and plasticiser interact and

combine together with water

and clay on a molecular

level and at what ratio are

they present in the gallery

Clay sheet e.g. Na-Montmorillonite

Na0.3(Al1.7Mg0.3)Si4O10(OH)2

Influence of the:

exchange cation

layer charge density

layer charge location

Water

Gallery cation

Bio-polymer Starch

Clay sheet

Plasticiser Polyethylene glycol

H-(O-CH2-CH2)n-OH

Al

Si

C

O

H

Na

Molecular systems under scrutiny

* Experimental data from Fu et al., Clays Clay Miner (1990) 38: 485

d00

1-sp

acin

g (

Å)

(bas

al s

pac

ing

)

122 H2O (35 pph) molecules in the clay

gallery at standard Temperature and Pressure

Swelling behaviour of clay–water system

single-layer hydrate

bi-layer hydrate

* Experimental data from Fu et al., Clays Clay Miner (1990) 38: 485

Swelling behaviour of clay–water system

d00

1-sp

acin

g (

Å)

122 H2O (35 pph) molecules in the clay

gallery at standard Temperature and Pressure

Swelling behaviour of anhydrous clay–PEG200 composite

Increase of basal spacing

XRD spectra of Na+-cloisite®

with different loads of PEG200

Basal spacing of PEG200-clay composite

experiment

27 pph

18 pph

12 pph

9 pph

3 pph

Swelling behaviour of anhydrous clay–PEG200 composite

Increase of basal spacing

XRD spectra of Na+-cloisite®

with different loads of PEG200

Basal spacing of PEG200-clay composite

experimental vs simulation study

27 pph

18 pph

12 pph

9 pph

3 pph

Effect of layer charge on PEG200 conformation

Increase of layer charge Low charge clay High charge clay

85.0 meq

“Saturn ring”

104.4 & 113.1 meq

“Bridging” two cations

Effect of charge location on PEG200 conformation C

harg

e lo

catio

n

Oh

Th

Increase of layer charge Low charge clay High charge clay

non-planar

Bridging two cations

planar

Bridging two cations

“Crown”

“Saturn ring”

Influence of starch on clay–PEG200 composite

21

Systems with any amylose content in

the gallery shows distinct shoulder at

21-22 Å which is correlating with

experimental data

Influence of starch on clay–PEG200 composite

21

Systems with any amylose content in

the gallery shows distinct shoulder at

21-22 Å which is correlating with

experimental data

× The simulated clay hydration behaviour is in excellent agreement with

experimental findings behaviour

× The simulated plasticiser swelling behaviour of Na-montmorillonite is in

excellent compliance with experiment

+ Even in water

× Magnitude and clay layer charge location dictates plasticiser’s

conformation in the interlayer and resultant d-spacing

× Simulation of clay–PEG200–starch composites predict realistic basal

spacing of ~ 21 Å

Conclusions

Thank you for your attention!!!