Shake gels

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  • It is soluble in water and other polar solvents. Being a branched polymer, it is extensively used as a binder in many pharmaceutical, adhesive industries.
  • Shake gels

    1. 1. CH5011-COLLOIDS AND SURFACES Jayadheer A (CH09B001) Sai Prashanth Reddy D (CH09B015) Nirup Kumar N (CH09B034) Krishna Teja R (CH09b050)
    2. 2.  To find the appropriate proportions of given polymer and particle solutions that forms a shake gel i.e., shears induced gelation. To verify the reversible gelation mechanism
    3. 3.  Interaction between PVP and the surface of silica takes place mainly by means of hydrogen bonds. Research has shown that PVP occurs in two forms on the silica surface, reversibly adsorbed and irreversibly grafted onto the surface of silica. The irreversible adsorption can be attributed to the formation of relatively strong –C=O….H-OSi hydrogen bonds whereas the interactions between Si and N.
    4. 4. Ref. Toki, TY Chow, T Ohnaka, H Samura, & T Saegusa, 1992)
    5. 5.  PVP (Polyvinylpyrrolidone k-30, average Mw = 40,000) Silica particles (LUDOX TM-50 colloidal silica, 50 wt. % suspension in water) Weighing balance Vacuum Pipette Milli-Q water Magnetic Stirrer Culture Bottles
    6. 6.  Polyvinylpyrrolidone also commonly called Polyvidone or Povidone, Monomer: N-vinylpyrrolidone.
    7. 7.  molecular weight of nearly 40,000 K value of 30 (Fikentschers formula) (Fikentschers Formula) Where, c = concentration in g/100 ml; c = viscosity of the solution; 0 = viscosity of the solvent; k = value according to Fikentscher (K = 1000* k) (Ref. Ashland_Inc)
    8. 8.  Spherical silica particles are suspended in an aqueous phase. The colloidal suspension is stabilized by pH adjustment and then concentrated, usually by evaporation. Brand Aldrich Formula SiO2 Mol Wt. 60.08 g/mol Density 1.4 g/ml @25 oC Table: Data for LUDOX TM-50 colloidal silica, 50 wt. % suspension in water (Ref. Aldrich)
    9. 9.  Polymer solution Colloidal Silica suspension Take different proportions of the solutions using micro-pipette Mix them in a culture bottle Shake the bottle to observe the formation of gel Repeat the experiment for various concentrations
    10. 10.  Glassware should be properly cleaned and sterilized in ovens or using nitrogen vents Store the micro pipette vertically to prevent liquids from running inside the shaft of the pipette. Minimize the exposure time for PVP while weighing, as it can gain weight by absorbing atmospheric water Should wear goggles and potentially lab aprons
    11. 11. Material Density (g/ml) @ 25oC Silica 50% 1.4 PVP 02% 1.008 PVP 10% 1.02 PVP 30% 1.07Table 2: Colloidal Silica data from manufacturer(Aldrich)and PVP data from (Ashland_Inc)
    12. 12. By Volume By Weight Inference2 % PVP 50 %Silica 2 % PVP 50 %Silica 1 1 1.008 1.4 Very less viscous mixture10 % PVP 50 %Silica 10 % PVP 50 %Silica 1 1 1.02 1.4 viscous liquid 1 3 1.02 4.2 more viscous 1 6 1.02 8.4 more viscous30 % PVP 50 %Silica 30 % PVP 50 %Silica 2 1 2.14 1.4 very high viscous 4 3 4.28 4.2 Some gel is formed 1 1 1.07 1.4 Some gel is formed 1 3 1.07 4.2 Shake gel 1 7 1.07 9.8 Shake gel
    13. 13. From Stanford Univ.
    14. 14.  The structure of the gel formed can be studied using IR spectroscopy, SEM, DLS and other relevant techniques The rheological properties like Visco-elasticity of the gel can be studied with changing the polymer and silica proportions.
    15. 15.  The gelation that occurred upon shaking the solution rigorously has contribution of both reversibly and irreversibly adsorbed polymer particles. When left to settle, a part of polymer desorbs and this can be attributed to reversible gelation A number of experiments were conducted using different concentrations, and proportions of PVP with 50% colloidal silica.
    16. 16.  Experiments were also conducted using PVA as polymer. Since, 20% PVA solution formed a very viscous fluid, PVP was considered for further experiments Using 30% PVP and 50% Silica in 1:1 volume proportions, a near gel was formed. So, different proportions of these mixtures were tried and a near shake gel is finally obtained. Increasing the proportion of silica particles led to the formation of better shake gels. This also supports the mechanism of reversible gelation.
    17. 17.  Belyakova, L. A., Anatoly M. Varvarin, Diana Y. Lyashenko, & Nadiya V. Roik. (2003). Study of interaction of poly(1-vinyl-2-pyrrolidone) with a surface. Colloid Interface Sci., 264, 2–6. Spinde, K., Konstantinos Pachis, Joanna Antonakaki, & Silvia. (2011). Influence of Polyamines and Related Macromolecules on Silicic Acid Polycondensation: Relevance to “Soluble Silicon Pools”? Chemistry of Materials, 4676–4687. Toki, M., TY Chow, T Ohnaka, H Samura, & T Saegusa. (1992). Structure of poly (vinylpyrrolidone)-silica hybrid. Polymer Bulletin, 36. Aldrich, S. (n.d.). LUDOX® TM-50 colloidal silica. Retrieved Nov 10, 2012, from http://www.sigmaaldrich.com/catalog/product/aldrich/420778?lang=en&regio n=IN Ashland_Inc. (n.d.). IspCorp. Retrieved Nov 10, 2012, from http://online1.ispcorp.com/Brochures/Performance%20Chemicals/PVP.pdf
    18. 18. Thank You 

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