@article{PavlitschekGretzPlank2013, author = {Pavlitschek, Tom and Gretz, Markus and Plank, Johann}, title = {Effect of Ca2+ Ions on the Film Formation of an Anionic Styrene/n-Butylacrylate Latexpolymer in Cement Pore Solution}, series = {Advanced Materials Research}, volume = {687}, journal = {Advanced Materials Research}, pages = {322 -- 328}, year = {2013}, abstract = {Several methods were employed to study the time dependent film formation of a self synthesized anionic latex dispersion in water and cement pore solution. First, a model carboxylated styrene/n-butyl acrylate latex dispersion possessing a minimum film forming temperature (MFFT) of 18 °C and a glass transition temperature (Tg) of 30 °C was synthesized via emulsion polymerization. Next, its film forming behaviour was studied at 40 °C, using an ESEM instrument. The analysis revealed that upon removal of water, film formation occurs as a result of particle packing, particle deformation and finally particle coalescence. Film formation is significantly hindered in synthetic cement pore solution. This effect can be ascribed to adsorption of Ca2+ ions onto the surface of the anionic latex particles and to interfacial secondary phases. This layer of adsorbed Ca2+ ions hinders interdiffusion of the macromolecules and subsequent film formation of the latex polymer.}, language = {en} } @article{PavlitschekGretzPlank2013, author = {Pavlitschek, Tom and Gretz, Markus and Plank, Johann}, title = {Novel Core-Shell Hybrid Polymers Designed as Dual Functional Additives for Concrete}, series = {Advanced Materials Research}, volume = {687}, journal = {Advanced Materials Research}, pages = {77 -- 83}, year = {2013}, abstract = {Novel hybrid admixtures for construction applications were prepared by layer-by-layer deposition technique. Colloidal core templates consisting of styrene/n-butylacrylate latex particles were coated with multilayers of superplasticizers commonly used in concrete. This way, core-shell particles possessing both dispersing and film-forming properties were achieved. Incorporation of the latex@dispersant hybrid additive into a cement paste results in a slow release of the superplasticizer as a result of gradual shell disintegration which instigates prolonged plastification (long "slump life") of the cement slurry. Once the shell has been dissolved, latex particles are released into the pore solution and can coalesce into a polymer film which improves the mechanical properties of the hardened cement. Characterization of the templates and novel additives was performed by means of zeta potential measurement, dynamic light scattering and electron microscopy. Our method allows to synthesize multifunctional additives with time-controlled release effect.}, language = {en} } @article{PavlitschekGretzPlank2013, author = {Pavlitschek, Tom and Gretz, Markus and Plank, Johann}, title = {Microcapsules prepared from polycondensate-based cement superplasticizers via layer-by-layer self assembly on melamine-formaldehyde core templates}, series = {Journal of Applied Polymer Science}, volume = {127}, journal = {Journal of Applied Polymer Science}, number = {5}, publisher = {Wiley}, pages = {3705 -- 3711}, year = {2013}, abstract = {Novel microcapsules were prepared from colloidal core-shell particles by acid dissolution of the organic core. Weakly crosslinked, monodisperse and spherical melamine-formaldehyde polycondensate particles (diameter ∼ 1 μm) were synthesized as core template and coated with multilayers of an anionic polyelectrolyte via layer-by-layer deposition technique. As polyelectrolytes, an anionic naphthalenesulfonate formaldehyde polycondensate that is a common concrete superplasticizer and thus industrially available, and cationic poly(allylamine hydrochloride) were used. Core removal was achieved by soaking the core-shell particles in aqueous hydrochloric acid at pH 1.6, resulting in hollow microcapsules consisting of the polyelectrolytes. Characterization of the template, the core-shell particles, and the microcapsules plus tracking of the layer-by-layer polyelectrolyte deposition was performed by means of zeta potential measurement and scanning electron microscopy. The microcapsules might be useful as microcontainers for cement additives.}, language = {en} } @inproceedings{GretzPlankPavlitschek2010, author = {Gretz, Markus and Plank, Johann and Pavlitschek, Tom}, title = {ESEM-Untersuchungen zum Verfilmungsverhalten von Latex-Dispersionen in Wasser und Zementporenl{\"o}sung}, series = {GDCh Monographie Bauchemie, Band 42}, booktitle = {GDCh Monographie Bauchemie, Band 42}, editor = {GDCh-Fachgruppe Bauchemie,}, isbn = {978-3-936028-65-2}, pages = {144 -- 151}, year = {2010}, language = {de} }