0000000000364661
AUTHOR
A. Strack
Spherical and rod-like colloids with polymer-brush surfaces
In this paper, we describe a strategy to overcome incompatibility of colloidal particles and polymer coils as well as immiscibility of spherical and rod-shaped nanoparticles. Two new types of model colloids are presented, colloidal nanospheres with hairy surfaces (spherical brushes) and polymacromonomers to represent cylindrical brushes. The spherical brushes are synthesized from polyorganosiloxane-μ-gels of diameter 20 nm by grafting onto anionically prepared polystyrene macromonomers of molecular weight M w=5000 g/mol. On average, each sphere has a surface layer of 200 polymer chains. Compatibility of spherical nanoparticles with polymer coils was probed by turbidity of as-cast films as w…
Nanowear on Polymer Films of Different Architecture
In this paper, we describe atomic force microscope (AFM) friction experiments on different polymers. The aim was to analyze the influence of the physical architecture of the polymer on the degree and mode of wear and on the wear mode. Experiments were carried out with (1) linear polystyrene (PS) and cycloolefinic copolymers of ethylene and norbornene, which are stabilized by entanglements, (2) mechanically stretched PS, (3) polyisoprene-b-polystyrene diblock copolymers, with varying composition, (4) brush polymers consisting of a poly(methyl methacrylate) (PMMA) backbone and PS side chains, (5) PMMA and PS brushes grafted from a silicon wafer, (6) plasma-polymerized PS, and (7) chemically c…
Synthesis and large scale fractionation of non-linear polymers: brushes and hyperbranched polymers
Polymer brushes with poly(methyl methacrylate) (PMMA) backbone and polystyrene side chains were synthesized by radical polymerization of ω-methacryloyl-polystyrene macromonomers. Hyperbranched PMMA was obtained by means of self-condensing group transfer copolymerization of methyl methacrylate with an initiator-monomer containing a polymerizable methacryloyl moiety and an initiating silylketeneacetal function. Both non-linear products were fractionated using the method of continuous polymer fractionation, consisting in a particular type of continuous countercurrent extraction. The combination of methyl ethyl ketone (solvent) with acetone (AC) (precipitant) turned out to be suitable for the f…