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MP-SPR: A new optical technique for characterization of cellulose structure and kinetic interactions.
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MP-SPR: A new optical technique for characterization of cellulose structure and kinetic interactions • Nanocellulose can be used in different applications only by carefully selecting a favourable characteristics of the material. The nanomaterial properties are driven by its micro- and nanoscopic features, such as structure, shape, strength, ability to self-assemble,.. and surface properties as they drive the interface characteristics and by that the nature of the interactions. • Hence, with the shift from bulk cellulose to more sophisticated applications and products, it is necessary also to introduce new methods for characterization. • Multi-Parametric Surface Plasmon Resonance (SPR) enables characterization of dynamic changes in model cellulose thin films and gels in real-time. Refractive index, Thickness, Extinction coefficient, Density, Surface coverage, Swelling, Optical dispersion Kinetics, Affinity, Concentration, Adsorption/Absorption, Desorption, Adhesion Gold, very thin polymer layers Cellulose, PS, PET, PMMA, SiO2, TiO2, Al2O3, ITO, graphene, CNT, Pt, Pd, ...Thickness up to microns
MP-SPR: A new optical technique for characterization of cellulose structure and kinetic interactions Typical experiment set-up: Background measurement of an SPR sensor (typically SiO2 or Au) A model cellulose formed on the sensor (typically spin-coating or LB) The sensor is measured in air at two wavelengths (=> thickness and refractive index of the cellulose layer) Additional protective/functional coating can be added in-situ (electrodeposition, LbL) or ex-situ (ALD, CVD,..) Coated sensor is measured in air (=> thickness and refractive index of the coating) Gas or vapour or liquid can be introduced (=> dynamic swelling) Injections of interacting samples can be introduced (=> kinetics of binding, surface coverage, dry mass) Prism Optical interface Glass substrate Adhesion layer Plasmonic layer SENSOR Other material Functionalization Flow-cell Orelma et al, Biomacromolecules (2011) 10 Malmström et.al., Macromolecules (2013)
MP-SPR: A new optical technique for characterization of cellulose structure and kinetic interactions Barrier coating properties Surface coverage Interaction kinetics On cellulose model surfaces Orelma et al, Biomacromolecules (2011) Thickness optimization Self-assembly Dynamic structural changes Polymer at pH 9 Polymer at pH 4 Referenc at pH 9 Reference at pH 4 Malmström et.al., Macromolecules (2013)) Future steps include testing of other functional characteristics also on cellulose model surfaces.