TY - JOUR A1 - Gretz, Markus A1 - Plank, Johann T1 - An ESEM investigation of latex film formation in cement pore solution JF - Cement and Concrete Research N2 - Environmental scanning electron microscopy (ESEM) and complementary methods were employed to study the time dependent film formation of a 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 was synthesized in aqueous media via emulsion polymerization. Its film forming property was at a temperature of 40 °C, studied under an ESEM. 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 retarded when the latex dispersion is present in 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. KW - Construction Chemistry KW - Cement KW - Cement Pore Solution KW - Latex-Particles Y1 - 2021 UR - https://doi.org/10.1016/j.cemconres.2010.11.005 VL - 41 IS - 2 SP - 184 EP - 190 PB - Elsevier ER - TY - JOUR A1 - Pavlitschek, Tom A1 - Gretz, Markus A1 - Plank, Johann T1 - Effect of Ca2+ Ions on the Film Formation of an Anionic Styrene/n-Butylacrylate Latexpolymer in Cement Pore Solution JF - Advanced Materials Research N2 - 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. KW - Construction Chemistry KW - Latex-Particles KW - Cement KW - Film Formation Y1 - 2021 UR - https://doi.org/10.4028/www.scientific.net/AMR.687.322 VL - 687 SP - 322 EP - 328 ER - TY - JOUR A1 - Gretz, Markus A1 - Plank, Johann T1 - Hybrid additives for construction applications, fabricated through layer-by-layer adsorption of polycondensate type superplasticizers on latex templates JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects N2 - Novel hybrid admixtures for construction applications were prepared by layer-by-layer deposition technique. Colloidal core templates consisting of styrene/acrylate latex particles were coated with multilayers of polycondensate-based dispersants 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 dispersant which instigates prolonged plastification of the cement slurry. Following disintegration of the shell, the latex core particles are released into the pore solution and coalesce into a polymer film which improves the mechanical properties of the hardened cement. Characterization of the templates and novel additives plus tracking of the layer-by-layer polyelectrolyte adsorption 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. KW - Construction Chemistry KW - Construction Additives KW - Cement Y1 - 2021 UR - https://doi.org/10.1016/j.colsurfa.2010.05.014 VL - 366 IS - 1–3 SP - 38 EP - 44 PB - Elsevier ER - TY - JOUR A1 - Gretz, Markus A1 - Plank, Johann T1 - Investigations on the interaction of cationic and anionic latex particles with Portland cement JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects N2 - The interaction between organic latex polymers and the surface of hydrating cement was investigated by measuring the zeta potential and adsorbed amount of polymer on cement. First, differently charged model latex particles were synthesized in aqueous media by well-known emulsion polymerization technique. The latex polymers were characterized by differential scanning calorimetry (DSC), dynamic light scattering (DLS) and environmental scanning electron microscopy (ESEM). Electrokinetic latex surface properties were investigated by means of streaming potential measurements using a particle charge detector (PCD). It is shown that the anionic latexes adsorb a considerable amount of Ca2+ from the cement pore solution. Next, adsorption of the latex polymers on the surface of hydrating cement was confirmed by zeta potential measurements using the electroacoustic method. A water to cement ratio in the cement paste as low as 0.5 was studied, representing actual conditions in mortar and concrete. Additionally, adsorption isotherms were determined in a sedimentation test using the depletion method. For all latex polymers, Langmuir type adsorption isotherms were found. The latex dosages required to achieve saturated adsorption on the cement surface obtained from zeta potential measurements correspond well with those determined in the sedimentation test. Electron microscopy photographs confirm that the charged latex polymers adsorb selectively on surface areas of hydrating cement showing opposite charge. This way, domains of organic latex polymers exist on the cement surface. They provide adhesion between the inorganic cement matrix and the organic polymer film formed later on by particle coalescence as a result of cement hydration and drying. KW - Construction Chemistry KW - Latex-Particles KW - Cement Y1 - 2021 UR - https://doi.org/10.1016/j.colsurfa.2008.08.005 VL - 330 IS - 2–3 SP - 227 EP - 233 PB - Elsevier ER - TY - JOUR A1 - Pavlitschek, Tom A1 - Gretz, Markus A1 - Plank, Johann T1 - Microcapsules prepared from polycondensate-based cement superplasticizers via layer-by-layer self assembly on melamine-formaldehyde core templates JF - Journal of Applied Polymer Science N2 - 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. KW - Construction Chemistry KW - Cement KW - Construction Chemical Additives Y1 - 2021 UR - https://doi.org/10.1002/app.37981 VL - 127 IS - 5 SP - 3705 EP - 3711 PB - Wiley ER - TY - JOUR A1 - Pavlitschek, Tom A1 - Gretz, Markus A1 - Plank, Johann T1 - Novel Core-Shell Hybrid Polymers Designed as Dual Functional Additives for Concrete JF - Advanced Materials Research N2 - 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. KW - Construction Chemistry KW - Cement KW - Concrete KW - Latex-Particles Y1 - 2021 UR - https://doi.org/10.4028/www.scientific.net/AMR.687.77 VL - 687 SP - 77 EP - 83 ER -