We enjoy designing complex colloidal particles

 

We have an in-depth knowledge of heterogeneous polymerization techniques, such as emulsion and mini-emulsion polymerizations, to develop a plethora of complex polymer-based colloids.

We love emulsion polymerization

Our most noticeable contributions to the field include the first reversible-deactivation nitroxide-mediated radical emulsion polymerization (Macromolecules 1997: DOI 10.1021/ma961003s), and the development and mechanistic understanding of Pickering mini-emulsion (Macromolecules 2005: DOI 10.1021/ma051070z) and emulsion polymerization processes (J. Am. Chem. Soc. 2008: DOI 10.1021/ja807242k).

check out our latest on pickering emulsion polymerization by clicking on the image below

Artistic Representation of the mechanism of Pickering emulsion polymerization, a process whereby polymer latexes are decorated with an armour of nanoparticles on their surface during their synthesis.

Artistic Representation of the mechanism of Pickering emulsion polymerization, a process whereby polymer latexes are decorated with an armour of nanoparticles on their surface during their synthesis.

We are back in the field of reversible deactivation radical emulsion polymerization

In 1995/1996 the people at CSIRO (Australia) reported on using methacrylate-based macromonomers as RAFT agents. Under starved-fed emulsion polymerization conditions this sulfur-free RAFT technique shows control of propagation of methacrylate monomers allowing for the synthesis of blockcopolymers, often with a narrow molar mass distribution.

We developed this pioneering work further and showed in 2017 that polymerization induced self-assembly (PISA) in water is possible using these RAFT agents. Click on the picture below to find out more.

One quest in emulsion polymerization technology that remains challenging and intriguing is control of the particle morphology. It is of importance as the architecture of the polymer colloid influences its behavioural properties when used in applications. We report in ACS Nano in 2019 an elegant innovation in the emulsion polymerization process which makes use of nanogels as stabilizers and allows us to fabricate Janus and patchy polymer colloids. Click on the image below to find out more.

False coloured SEM images of emulsion polymerizations using nanogels as stabilizers (N1) at 2.8 wt% wrt monomer in which the pH was adjusted to 8.8 (A), 5.5 (B), 5.0 (C) and 4.5 (D) prior to polymerization. Scale bars: 100 nm.

False coloured SEM images of emulsion polymerizations using nanogels as stabilizers (N1) at 2.8 wt% wrt monomer in which the pH was adjusted to 8.8 (A), 5.5 (B), 5.0 (C) and 4.5 (D) prior to polymerization. Scale bars: 100 nm.

Moving away from “Plastics”

We currently have launched collaborative programs with industry to look at alternative approaches to fabricate latexes and microparticles/capsules NOT using traditional radical polymerization methodologies.

Beside this, we recently have expanded our particle synthesis and characterization portfolio to inorganic colloids, such as silicates, metal oxides and calcium carbonate.

 

 
In our  2015  paper entitled  Fabrication of calcium phosphate microcapsules using emulsion droplets stabilized with branched copolymers as templates  published in  Journal of Materials Chemistry B  we report on a versatile and time-efficient method to fabricate calcium phosphate (CaP) microcapsules. The branched copolymer was designed to provide a suitable architecture and functionality to produce stable emulsion droplets, and to permit the mineralization of CaP at the surface of the oil droplet when incubated in a solution containing calcium and phosphate ions. The CaP shells of the microcapsules were established to be calcium deficient hydroxyapatite with incorporated chlorine and carbonate species. These capsule walls were made fluorescent by decoration with a fluorescein–bisphosphonate conjugate. The images above are  SEM micrographs  illustrating the mineralization of CaP at the surface of oil droplets stabilized with BCP. (A) Incubation periods of 0 hours (scale bar = 37 µm), (B) 48 hours (scale bar = 16 µm), (C) 60 hours (scale bar = 7 µm), (D and E) 72 hours (scale bars = 23 µm and 7 µm, respectively), (F) surface morphology of CaP capsule (scale bar = 704 nm), (G) CaP capsules annealed at 600 oC (scale bar = 2 µm), (H) surface morphology of CaP capsule after annealing at 600 oC (scale bar = 648 nm), and (I and J) shell thickness of the CaP capsules before annealing (scale bars = 1 µm and 540 nm, respectively). You can read the (open access) paper here:  http://dx.doi.org/10.1039/C5TB00893J .

In our 2015 paper entitled Fabrication of calcium phosphate microcapsules using emulsion droplets stabilized with branched copolymers as templates published in Journal of Materials Chemistry B we report on a versatile and time-efficient method to fabricate calcium phosphate (CaP) microcapsules. The branched copolymer was designed to provide a suitable architecture and functionality to produce stable emulsion droplets, and to permit the mineralization of CaP at the surface of the oil droplet when incubated in a solution containing calcium and phosphate ions. The CaP shells of the microcapsules were established to be calcium deficient hydroxyapatite with incorporated chlorine and carbonate species. These capsule walls were made fluorescent by decoration with a fluorescein–bisphosphonate conjugate. The images above are SEM micrographs illustrating the mineralization of CaP at the surface of oil droplets stabilized with BCP. (A) Incubation periods of 0 hours (scale bar = 37 µm), (B) 48 hours (scale bar = 16 µm), (C) 60 hours (scale bar = 7 µm), (D and E) 72 hours (scale bars = 23 µm and 7 µm, respectively), (F) surface morphology of CaP capsule (scale bar = 704 nm), (G) CaP capsules annealed at 600 oC (scale bar = 2 µm), (H) surface morphology of CaP capsule after annealing at 600 oC (scale bar = 648 nm), and (I and J) shell thickness of the CaP capsules before annealing (scale bars = 1 µm and 540 nm, respectively). You can read the (open access) paper here: http://dx.doi.org/10.1039/C5TB00893J.