Polymer modified colloidal dispersions |
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| Authors: | P Sakellariou T A Strivens F Petit |
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| Institution: | (1) ICI Paints, Wexham Road, SL2 5DS Slough, UK;(2) Present address: New Technology Group, Courtaulds Coatings Ltd., Stoneygate Lane Felling, NE10 OJY Gateshead Tyne & Wear, UK;(3) Laboratoire Physicochimie Structurale et Macromoleculaire, ESPCI, Paris, France |
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| Abstract: | The effect of added polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) on a dispersion of polystyrene particles stabilised with grafted methoxy PEG chains is discussed. PVA adsorbed more strongly on the particles compared to PVP. Polymer addition led to stable mixtures in the case of PVA compared to depletion phase separation observed in the case of PVP. Rheological measurements showed thickening of the dispersion and absence of any structure in the case of PVA, in contrast to structure formation in the case of PVP due to depletion phase separation. A weak gel state was reached for ca. 7% w/w PVP. The observed behaviour is in accord with the relative propensity of PVA and PVP to interact with the particle surface, the grafted chains and their solubility in water. The solvency of the free polymer chains dominated the overall behaviour while the contribution from the incompatibility between free and grafted chains was conterbalanced by differences in the free polymer adsorption on the particles. |
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| Keywords: | Colloidal dispersion polymer particles interactions phase diagram depletion phase separation rheology structure |
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