Browsing by Author "Smyth, Matthew"

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  • All-lignin approach to prepare cationic colloidal lignin particles: Stabilization of durable Pickering emulsions
    (2017) Sipponen, Mika; Smyth, Matthew; Leskinen, Timo; Johansson, Leena-Sisko; Österberg, Monika
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Surface modification of colloidal lignin particles (CLPs), which are obtained from renewable resources, is a plausible route towards novel biomaterials. Here we show that adsorption of cationic lignin onto spherical CLPs produces positively charged particles with tailored properties for the stabilization of Pickering emulsions. The threshold dosing of cationic lignin needed to achieve colloidally stable cationic dispersions was 4% relative to the dry weight of CLPs. Compared to irregular kraft lignin particles or regular CLPs, cationic CLPs stabilized a broader array of durable Pickering emulsions. This all-lignin adsorption process to prepare cationic CLPs is advantageous because it minimizes the consumption of synthetic polymers, and opens new application opportunities for structurally defined nano- and microscale lignin particles.
  • Scaling up production of colloidal lignin particles
    (2017) Leskinen, Timo; Smyth, Matthew; Xiao, Yao; Lintinen, Kalle; Mattinen, Maija-Liisa; Kostiainen, Mauri A.; Oinas, Pekka; Osterberg, Monika
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Fundamentals of nanoprecipitation process to form colloidal lignin particles (CLPs) from tetrahydrofuran (THF)-water solvent system were studied, and applied in establishment of a robust reactor design for scaled-up CLP production. Spherical lignin particles with an average diameter of 220 nm could be produced by the new reactor design. Evaporation was applied for removal of THF, concentration of the CLP dispersions, and finally for drying of the CLPs into flake like dry form. The dried CLPs could be re-dispersed in water to restore their colloidal form by applying short physical agitation. Salt triggered sedimentation of the particles was also investigated as a way for reducing the energy consumption related to water evaporation from the CLP dispersions. Aqueous thermal post-treatments were demonstrated to yield structural reinforcement of the CLP structure against solvation in various lignin solvents. In summary, the presented work pushes forward the conceptual design of large-scale CLP production, and addresses some of the foreseen technical challenges.