press release

BonLab collaborates to produce bacteria containing biocoatings

BonLab collaborates to produce bacteria containing biocoatings

We have a long history of making polymer dispersions to be used in waterborne coatings. The polymer colloids, or latex particles, are made by emulsion polymerization. Prof. Joe Keddie from the Physics Department at Surrey University contacted us if we were interested to help out on a bio-coatings project that needed some bespoke polymer latexes and colloidal formulations. With the term bio-coatings we mean here the coating formulation has the ability to entrap metabolically-active bacteria within the dried polymer film.

We loved the concept. In BonLab, PhD student Josh Booth optimized the synthesis of acrylic polymer latexes at approximately 40wt% solids with a monomodal particle size distributions. Important was to use bacteria-friendly surfactants in the semi-batch emulsion polymerization processes. Important was also to have a dry glass transition temperature of the polymer latex binder around 34 ℃, so that film formation could occur at temperatures which preserved viability of the bacteria.

The latexes were formulated as mixtures with halloysite nanoclay (hollow tubes) and E coli bacteria back at Surrey. The tubular clay was introduced to create porosity inside the polymer nanocomposite films. The overall composition of the waterborne formulation was optimized for mechanical and bacterial performance.

New method to study chain transfer in radical polymerizations

New method to study chain transfer in radical polymerizations

Synthetic polymers in most cases do not have one bespoke molecular weight. A sample typically consists of a large number of individual polymer chains, each having a different molecular weight. The average molecular weights and the shape of the molecular weight distribution are a kinetic fingerprint of how to polymer material was made. The resulting molecular weight distribution dictates physical and mechanical properties.

In free radical polymerizations, four key mechanistic events need to be considered. These are initiation, propagation, termination, and chain transfer. The latter often gets brushed under the carpet in introductory textbooks, but is pivotal.

When one targets polymers of low molecular weight, chain transfer agents are often used. One prominent class of chain transfer agents are thiol compounds, for example n-dodecanethiol. To understand how the molecular weight distribution develops throughout the polymerization process, the ability to determine the reactivity of the chain transfer agent is crucial. This reactivity is often expressed in the form of a chain transfer constant, Ctr, which is the ratio of the rate coefficients of chain transfer and propagation.

BonLab wins awards and prizes for Innovative Research

The BonLab team has recently won a number of awards and prizes in recognition for their innovative research in the field of polymer colloid science.

In April 2019 at the RSC/SCI Rideal Lecture in honour of prof. Peter Lovell Sam Wilson Whitford won the RSC Soft Matter poster prize for his work on microcapsules based on supramolecular waxes. At the same meeting Matt Donald won the RSC Polymer Chemistry poster prize for his work on the mechanistic aspects of vinyl acetate emulsion polymerization.

In May 2019 Wai Hin Lee was awarded a prestigious Warwick International Chancellor’s Scholarship to continue his PhD in complex 2D colloidal materials. Brooke Longbottom was awarded a Warwick University faculty of science PhD thesis prize for his outstanding contributions to the field of “active” colloidal particles.

In June 2019 Andrea Lotierzo was awarded best PhD student presentation at the International Polymer Colloids Group Conference in Singapore, for his work on the synthesis of Janus, patchy and armored latex particles.

Prof.dr.ir. Stefan Bon, leader of the BonLab, says: “ I am delighted with our recent awards and prizes and I am proud of the achievements of Sam, Matt, Wai, Brooke and Andrea. They all have worked tremendously hard with dedication and enthusiasm and all are the reason why BonLab continues to innovate in science”