A method for chemically modifying a surface with grafted monolayers of initiator groups, which can be used for a "living" free radical photopolymerization, is described. By using "living" free radical polymerizations, we were able to control the length of the grafted polymer chains and therefore the layer thickness up to ∼100 nm. Also, single-layer grafted block copolymers were obtained by subsequent polymerizations of styrene and methyl methacrylate monomers. The surface-grafted polymer and block copolymer layers were evidenced by direct imaging methods (transmission and scanning electron microscopy) and by indirect surface characterization methods (contact angle measurements, SFM, XPS, and IR). The ability to control the thickness of the grafted polymer as well as the synthesis of a grafted block copolymer layer in a well-defined manner affirms the "living" character of the surface-initiated free radical photopolymerization.

The preparation of inorganic–organic core–shell particles is presented. These particles, composed of a titanium dioxide core and a polymer shell, are prepared via precipitation polymerization and inverse microsuspension polymerization. The electrical and optical properties of dispersions of these particles in a paraffin oil are measured in view of the formulation of electronic inks for electrophoretic displays. Encapsulation of TiO2 by precipitation polymerization is improved by pretreating the pigments with 3-(trimethoxysilyl)propyl methacrylate, making it possible to prepare particles with a TiO2-to-polymer ratio varying over a wide range. This ratio has a considerable influence on the optical properties of the dispersion but also on the interactions between pigments and electrodes. The polymer shell can then be further functionalized by introducing acidic groups at the particle’s surface. Encapsulation of the TiO2 can also be achieved by inverse microsuspension polymerization of poly(sodium acrylate), allowing the introduction of the acidic groups in one step only. Finally, dispersions of TiO2−polymer particles in black dyed paraffin oil have successfully been applied in an A4-sized segmented electrophoretic display panel.

A new synthetic approach for the preparation of mechanically linked polyrotaxanes was developed. Two variations of rotaxane monomers were synthesized, based on diphenylmethane and tetraphenylmethane blocking groups. Both rotaxanes bear a protected phenol functionality in the dumbbell-shaped part and a protected carboxylic acid functionality in the cyclic component. Via a "stepwise" polymerization, a rotaxane dimer and a rotaxane tetramer have been obtained. The procedure involves selective deprotection of the two functional groups in separate batches and a subsequent coupling reaction of the produced monofunctional/monoprotected monomers so that a dimer is formed. Longer and monodisperse oligomers can easily be obtained by repetition of this procedure. In addition, deprotection of both functionalities in the dimer and subsequent esterification resulted in the formation of a polymer with a molecular weight of ca. 400 000. The molecules obtained were isolated and characterized by 1 H NMR and mass spectrometry.

In this letter we report the study of surface chemical reactions with scanning force microscopy (SFM) with chemical specificity. Using chemically modified SFM probes, we can determine the local surface reaction conversion during a chemical surface modification. The adhesion forces between a functionalized tip and a chemically modified surface were used to calculate local reaction conversions on a molecular level on model substrates. Moreover, the distribution of reacted (and unreacted) functional groups could be mapped by chemically specific lateral force imaging. This technique was applied to study surface modifications of polyethylene films upon etching with chromic acid.

No abstract