Frank Driessen

Thiolactone chemistry and copper-mediated CRP for the development of well-defined amphiphilic dispersing agents

A straightforward synthetic pathway was developed for the synthesis of amphiphilic graft and toothbrush copolymers by combining copper-mediated controlled radical polymerization with the thiolactone-based amine–thiol–ene conjugation in a “grafting-onto approach”. First, a series of well-defined, thiolactone containing macromolecular backbones were synthesized via copolymerization with a thiolactone-containing monomer. Next, acrylate end-functionalized polymers were obtained in a post-polymerization modification procedure and coupled to the backbones. Furthermore, in-depth characterization of the different structures was performed by the use of SEC, NMR, MALDI-TOF and LCxSEC analysis. In order to demonstrate the amphiphilic behaviour of these graft and toothbrush copolymers, micelle formation tests were carried out and measured with DLS and TEM, while the dispersing features of these comb-like copolymers were evaluated by pigment stabilization tests.

Double Modification of Polymer End Groups through Thiolactone Chemistry

A straightforward synthetic procedure for the double modification and polymer-polymer conjugation of telechelic polymers is performed through amine-thiol-ene conjugation. Thiolactone end-functionalized polymers are prepared via two different methods, through controlled radical polymerization of a thiolactone-containing initiator, or by modification of available end-functionalized polymers. Next, these different linear polymers are treated with a variety of amine/acrylate-combinations in a one-pot procedure, creating a library of tailored end-functionalized polymers. End group conversions are monitored via SEC, NMR, and MALDI-TOF analysis, confirming the quantitative modification after each step. Finally, this strategy is applied for the synthesis of block copolymers via polymer-polymer conjugation and the successful outcome is analyzed via LCxSEC measurements.

Straightforward RAFT Procedure for the Synthesis of Heterotelechelic Poly(acrylamide)s

Heterotelechelic, hydrophilic polymers with a primary amine and thiol group at the α- and ω-chain end, respectively, are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in a straightforward and versatile way and subsequently used for the design of dual-responsive polymer/gold nanohybrids. Therefore, a phthalimido-containing chain transfer agent (CTA) is synthesized and used for the polymerization of the hydrophilic monomers N-isopropylacrylamide (NIPAM) and N,N-dimethylacrylamide (DMA). After polymerization, the trithiocarbonate functionality at the ω-chain end, originating from the CTA, is converted into a thiol upon aminolysis. In the next step, the phthalimido α-chain end is hydrolyzed into a primary amine, resulting in heterotelechelic, hydrophilic polymers. End-group conversions are monitored by (1)H NMR spectroscopy, MALDI-TOF MS analysis, and UV-Vis spectroscopy, confirming that quantitative modifications are obtained during each stage. The amino groups of these heterotelechelic polymer chains are modified with citraconic anhydride, after which the obtained polymers are grafted with the thiol group onto citrate-stabilized gold nanoparticles resulting in the creation of dual-temperature- and pH-responsive gold particles.