Block versus block-like copolymers: comparative study and exploration of a continuous preparation method

In polymer research there is a huge interest for amphiphilic block copolymers, consisting of a hydrophilic and a hydrophobic segment, as they show a unique surfactant behaviour with a wide variety of applications. In order to tune the properties of these materials, and as a consequence the resulting applications, the use of a controlled radical polymerization, in particular atom transfer radical polymerization (ATRP), is indispensible. Traditional block copolymers are synthesized via a macroinitiator strategy. This two-step procedure is rather time and solvent consuming because of the intermediate purification step. By consequence, such a synthetic strategy is not industrially attractive. Therefore, in this research project, a one-step procedure has been developed based on a sequential monomer addition, with the formation of so-called block-like copolymers. By this procedure, no intermediate purification step is required after the synthesis of the first segment. It would be economically much more interesting to use this one-step procedure compared to the macroinitiator strategy, provided that copolymers can be prepared with similar properties. For this reason, a detailed comparative study of both synthetic strategies has been performed to verify whether equivalent copolymer structures can be prepared. Moreover, via two column reactors in series, it would be possible to produce the block-like copolymers in a continuous way. In order to fully understand this continuous polymerization process and to allow for a better control over the copolymer structure, a kinetic model for the continuous block-like copolymerization has been set up. Finally, a novel type of solid-support for copper catalyzed reactions has been developed, based on macroporous cryogels. Because of the unhindered flow through the matrix, this support allows for the application in continuous column reactors with in situ catalyst separation. The new catalyst support has been tested for two types of continuous heterogeneous copper catalyzed reactions: the azide-alkyne click coupling and ATRP

Structure of adsorption layers of amphiphilic copolymers on inorganic or organic particle surfaces

The structure of adsorption layers of amphiphilic block and block-like copolymers of poly(isobornyl acrylate) and poly(acrylic acid) on the surface of hydrophilic titanium dioxide and hydrophobic copper phthalocyanine (CuPc) pigments in an aqueous studied by the electrokinetic sonic amplitude (ESA) method. The electroacoustic behaviour of the polyelectrolyte block copolymer-coated particles could be described in the context of the polymer gel layer theory. The polymer layer around the particles was found to be much thinner for CuPc as compared to the TiO2 substrate. This is attributed to differences in the adsorption mechanism and the composition of the adsorption layer normal to the substrate surface. Adsorption models were established that consider effects of the copolymer structure

Heterogeneous azide-alkyne click chemistry: towards metal-free end products

Heterogeneous copper catalyzed azide-alkyne click chemistry (CuAAc) has been a quickly emerging research field during the last couple of years as it shows many advantages in comparison to its homogeneous counterpart. In this Minireview, an overview of the state-of-the-art is presented for the first time. For the sake of completeness, not only successful heterogeneous supports but also systems that particularly failed will be discussed. Furthermore, the future prospects and challenges with regard to the application of heterogeneous CuAAC are highlighted