Research themes in the Klumperman group are:
Synthesis and characterization of advanced macromoleular architectures
The main emphasis in this research theme is the synthesis of complex materials via reversible deactivation radical polymerization techniques. Although not exclusively restricted to this family of techniques, RAFT, ATRP and (to a lesser extent) NMP are the main synthetic tools in the group. Within the various projects we synthesize homo- and hetero-telechelic polymers, diblock copolymers, and molecular brushes. The resulting polymers are further utilized for the synthesis of hydrogels, the development of drug delivery vehicles and self-assembly into cylindrical or tubular aggregates, respectively. The figure shows an example of early work on hetero-arm molecular brushes in our group. It looks as if the polymers adopt a toroidal conformation in a selective solvent for one of the arms.
Morphology control on the nanometer length scale
Several different techniques are used to control the morphology of polymeric materials on the nanometer and micrometer length scale. The first one is self-assembly of amphiphilic polymers (block copolymers or amphiphilic brushes). A variety of structures is achieved via this technique, ranging from micelles to vesicles and cylindrical aggregates. A second technique is elecrospinning, which allows the formation of fibers with diameters in the submicron range. This technique is among others used in a project on the formation of antimicrobial membranes. The third technique is the self-assembly of particles on emulsion droplets to form a Pickering emulsion. The figure shows an example of partially sintered micron size particles assembled on a 50 micrometer droplet.
A strong focus in the group is on drug delivery systems and other advanced polymer systems that find their eventual application in the field of Nanomedicine. Especially polymer-protein and polymer-peptide conjugates are being investigated. In most cases we use RAFT-mediated polymerization to synthesize the required end-functional polymers. One of the chain ends is conjugated to the peptide or protein of interest, where the other end may be used for various purposes, such as fluorescent labeling, introduction of a targeting ligand, etc. Other explorative research in this field relates to the synthesis of reversible hydrogels that can be degraded upon exposure to a specific stimulus.