2012-02-08

Nanomaterials used in packaging

applications

Y. Wyser, Nestlé Research Center,

Lausanne, Switzerland

Definition

p. 2 Yves Wyser, Nestlé Research Center, Lausanne, Switzerland 2012-02-08

• ‘Nanomaterial’ means a natural, incidental or

manufactured material containing particles, in an

unbound state or as an aggregate or as an

agglomerate and where, for 50 % or more of the

particles in the number size distribution, one or more

external dimensions is in the size range 1 nm-100 nm.

• (a) ‘particle’ means a minute piece of matter with defined physical boundaries;

• (b) ‘agglomerate’ means a collection of weakly bound particles or aggregates where

the resulting external surface area is similar to the sum of the surface areas of the

individual components;

• (c) ‘aggregate’ means a particle comprising of strongly bound or fused particles.

COMMISSION RECOMMENDATION of 18 October 2011 on the definition of nanomaterial (2011/696/EU)

Exceptions

• In specific cases and where warranted by concerns for the

environment, health, safety or competitiveness the number size

distribution threshold of 50 % may be replaced by a threshold

between 1 and 50 %.

• By derogation from point 2, fullerenes, graphene flakes and single

wall carbon nanotubes with one or more external dimensions below

1 nm should be considered as nanomaterials.

p. 3 Yves Wyser, Nestlé Research Center, Lausanne, Switzerland 2012-02-08

Particles in an unbound state

• Definition from French legislation draft: Décret relatif à la

déclaration annuelle des substances à l’état nanoparticulaire:

– Susceptible to be extracted or released under normal or reasonably

foreseeable conditions of use

• I.e. packaging materials are in most cases not to be considered as

nanomaterials

– Quid about active packaging releasing nanomaterials?

• Some packaging materials are however produced using

nanomaterial.

p. 4 Yves Wyser, Nestlé Research Center, Lausanne, Switzerland 2012-02-08

Packaging nano-based materials classification

• Packaging materials

produced using nano-objects:

– Nanocomposites

• Packaging materials

produced by creating

nanostructures in-situ:

– Nanostructured materials

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Packaging materials produced using nano-objects:

Nanocomposites

• Particles

– 3 dimensions in the

nanometre range

– Processing aids,

active packaging

• Fibres

– 2 dimensions in the

nanometre range

– Mechanical

properties

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• Platelets

– 1 dimension in the

nanometer range

– Mechanical and barrier

properties, active

ingredient carriers

• General process

– Surface treatment of the nano-objects

– Surface grafting for compatibilization or separation

– Mixing with polymer (in melt, in solution) or with monomers followed

by in-situ polymerization

– Classical polymer processing techniques, inducing orientation when

needed.

Barrier improvement:

nano-platelets polymer composite

• Principle: the tortuous path

• Typical filler: Montmorilonite clay

– Ion exchange on the surface of the clay with medium length organic

molecules to separate layer improving intercalation / exfoliation

– Compounding with polymers or monomers: twin screw extruder,

reactive extrusion.

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Specific case: layer-by layer assembly of coatings

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20 nm

• High volume fraction

• Near to perfect alignment

Reproduced with authorization of J. C. Grunlan form M. A. Priolo, D. Gamboa, K. M. Holder, J. C. Grunlan

Nano Lett. 2010, 10, 4970–4974,

In-situ Nanostructured materials

• Materials having an internal or external structure in the nanometer

range created by the process without the addition of nano-objects

– Nanostructured surfaces

– Nano-blends

– Nano-coatings

– …

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Nanostructured surfaces

• The surface of packaging is the part that will interact most with

either the consumer or the product. In this sense, modifying its

properties can add new functionalities to packaging materials.

• Many applications in this domain apply the biomimetic approach,

i.e. the reproduction of features found in nature that have

functionalities of interest

– The lotus effect

– The Gecko effect

– Pigment less colouration

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Nanoblends

• Blends consist of a mixture of various polymers to improve some

properties of or add functionality to common polymers.

• Processing allows to control the blend morphology which influences

the efficiency.

• Having the blended polymer domains in the nanorange further

improves effectiveness and allows to retain transparency.

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Perm

eabili

ty

Volume percent

0100

A

B

C

Blend permeability

A Laminar structure

B Lamellar blend

C Particulate system

Nanoblends

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• PET / MXD 6 blends to improve barrier properties of bottles

• Passive barrier or scavenging barriers

Injected Preform Stretched bottle

Nanocoatings

• Nanocoatings have been available for

decades, and some are extensively

used

– thickness in the nanometer range and

comparatively infinite size in the other

dimensions

– e.g. metallisation, SiOx, AlOx.

• Act as a barrier to permeation and

migration, as chemical protection for the

substrate, or as surface property

modifiers.

• Physical Vapour Deposition (PVD) or

Chemical Vapour Deposition (CVD).

– Process under vacuum

– Plasma often used to enhance the

process

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Summary

p. 14 Yves Wyser, Nestlé Research Center, Lausanne, Switzerland 2012-02-08

Nanocomposite Nanocoatings Nanoblends Nanostructured

surfaces

Applications

•Barrier

•Active packaging

•Mechanical

•Barrier

•Surface properties

•Barrier (incl. scavenging )

•Active packaging (e.g. controlled release)

•Mechanical

•Visual effects

•Surface property

modifications

Process

Compounding of

nano-objects with

polymer matrices

Vacuum deposition of

a coating with

thickness in the

nanometer range

Blending of two or

more polymers,

compatibilisation to

obtain nano-sized

domains

“In-situ” manufacturing

of nanostructure.

(structures obtained by

addition/deposition of

particles fall under the

nanocomposite

category)