Bottom Up Synthesis: Organic Colloids and Nano Particles Polymer latex dispersions Global production of synthetic polymers 2000: ca. 190 Mio. t ca. 200 Bio. sales Global production of synthetic polymers, broken down by categories Polymer latex dispersions by product categories
Latex Dispersions
Latex Dispersions CH 2 CH CH 2 CH C O m O C 4 H 9 n CH 2 CH 2 m CH 2 CH O 2 2 C O CH 3 n
Synthesis of Latex Dispersions via Emulsion Polymerisation
Morphology of Latex Particles
Morphology of Latex Particles
Morphology of Latex Particles
Film Forming of Latex Particles (Coalescence)
Film Forming of Latex Particles (Coalescence) Film formation Minimum film-forming temperature MFFT Latex dispersion Above MFFT temperature, a homogeneous polymer film is formed elimination of water close sphere packing Depends on: Polymer composition particle deformation Surfactant (emulsifier) Particle size Particle morphology Coalescence into a Film
Film Formation (Coalescence)
Particle Coalescence (Film Forming Process) Latex particles at beginning of coalescence Starting coalescence (film formation) of anionic dispersion A2
Film Forming Process of Latex Polymers
Redispersible Powders in Tile Adhesives Only redispersible powders provide: - adhesion of tiles with sintered surface (low water uptake, E 0.5 %) - adhesion after 70 C storage Adhesion between sintered tile and mortar
Adhesion Tile Cement Mortar Achieved with Latex Dispersion
Industrial Applications of Latex Dispersions Paints and Coatings (Latex paint) provides adhesion, elastic (no cracks), low dirt Protection of buildings against corrosion and ageing water repellent, prevents attack by aggressive gases Building materials (tile adhesives, flooring compounds etc.) adhesion, flexibility Paper manufacturing Binder, surface coating Leather industry softness, strength, water repellent Textil and carpet coating strength enhancement Latex foams Adhesives etc.
3D Nanostructured Materials: Nanoporous Materials Preparation of nanoporous materials 1. 3D-Anordnung runder Partikel als Schablone ( opaline array ) 2. Infiltration einer flüssigen Matrix, z. B. UV-härtender Kunststoff oder Monomer + Initiator, mit einem nanoskaligen Kolloid (1 50 nm) als Precursor 3. Verfestigung der Matrix 4. Entfernung der kolloidalen Schablone (Extraktion mit Lösemittel, Zersetzung durch Säuren, thermische Zersetzung) Bei runden Partikeln als Schablone inverser Opal Kontrolle der Porengröße durch Größe der Schablone!!!
Aufbaureaktionen Herstellung poröser Silica-Strukturen: Templat: Monodisperse Polystyrol-Partikel (A) Infiltration mit Silica-Sol oder kolloidaler Nanosilica-Lösung Thermische Zersetzung des Templats Polystyrol bei 1100 C (B und C)
Aufbaureaktionen Steuerung der Porengröße
Aufbaureaktionen Poröse Silica-Matrix aus Silica-Sol (A) und Nanosilica- Partikeln (B)
3D Nanostructured Materials Preparation of 3D Arrays from colloidal primary particles A) Sedimentation under gravity simple method but take very long time (weeks and months) hard to control no control of lattice structure huge differences in density, particle > 0,5 µm B) Crystallisation in electrical field highly charged colloids spontaneous self-assembly (colloidal crystals) Structure is concentration dependent C) Physically controlled crystallisation
3D Nanostructured Materials Densly packed polystyrene particles (left) Crystal lattice structure made of nano particles
3D Nanostructured Materials Densely packed SiO 2 particles showing different lattice planes
3D Nanostructured Materials Bragg Equation Distance BD + DC = 2 * d hkl * sin θ = n * λ
3D Nanostructured Materials Opalescence of ordered structures from nano particles Colors of a synthetic opal, produced from nano particles SEM image of opal mineral from Australia
3D Nanostructured Materials Structures showing opalescence Opalescencing structure, made from 200 nm silica particles (a) and polymer coated 200 nm silica particles (b); SEM image of nanostructured arrangement of 200 nm silica particles (c)
Core-Shell Nano Particles Potential Structures of Particles composed of different materials Core-Shell Particle
Core-Shell Nano Particles Example: SnO 2 @SiO 2 particle Direct coating of nano particles through addition of alcoxides This method works only if particles attract each other (electrostatic attraction)
Multi-layered Nano Particles Kern ph Beschichtung Indirect coating through heterogeneous coagulation Example: SiO 2 @TiO 2 particle Zeta potential of a) SiO 2 b) TiO 2 c) SiO 2 @TiO 2 particle
Multilayered Nano Particles Gesamtwechselwirkung Anziehung Abstoßung Energie-Minimum= heterogene Koagulation Abstand der Teilchen 15 14 13 12 11 10 9 8 7 6 5 ph-wert 4 3 2 1 DLVO calculation of electrostatic interaction potential between two particles as a function of distance and ph value
Multilayered Nano Particles ph Coating of particles possessing same electric charge after charge reversal with auxiliary agent Coarse polystyrene particles coated with nanosized polystyrene particles
Multilayered Nano Particles Coating of silica with magnetite using a cationic polymer as auxiliary agent magnetic core-shell particle of well-defined nano size PolyDADMAC poly(diallyldimethyl ammoniumchloride) Zeta potential during coating of silica with magnetite via a cationic polymer TEM image of a) pure nano silica and b) silica coated with Fe 3 O 4
Multilayered Nano Materials Hybrid additive possessing core-shell structure Coating should be conducted at ph 7 Layer-by-Layer Deposition (LbL) to achieve a core-shell structure Concrete admixtures (polycondensates) were used to build multilayered nano materials Tracking of coating process via zeta potential measurement
Multilayered Nano Particles Hybrid additives Effectiveness as superplasticizers and film former 1. Dispersing effectiveness 2. Film formation Cement paste spread
Multilayered Nano Particles Nano Capsules Polyelectrolyte Nanocapsules Weakly crosslinked melamine formaldehyde polycondensate particles as soluble core templates, coated with anionic and cationic polyelectrolytes using thelbl deposition method; then removal of the core template by acid dissolution Melamine formaldehyde Core templates Nano capsules
Multilayered Nano Materials: Nano capsules Nano capsules made from polyallylamine hydrochloride / Polystyrene sulfonate
Multilayered Nano Materials: Nano Capsules Fluorescence coded micro capsules Template-assisted multilayer formation of micro capsules by LbL deposition Fluorescence coded micro capsules