BonLab fabricates textured microcapsules through crystallization

Microcapsules can be found in a range of commercial applications, including cosmetics, healthcare, agriculture, and food. The capsules serve as a storage vessel for an active ingredient, for example a nutrient or fragrance. They can have a variety of designs, the simplest form being a single internal liquid-based core surrounded by a solid shell. The chemical and physical characteristics of this shell influence the colloidal stability of capsules in formulations, dictate the permeability and mechanical robustness of the capsules, and can potentially regulate substrate adhesion. Beside storage, these features of the microcapsules are there to regulate and control release and delivery of the active compound.

A considerable part of the technologies used to produce microcapsule relies on the use of synthetic polymers that do not break down, with terrible consequences for environmental build up. One way is to make use of biocompatible and degradable plastics.

We provide an alternative solution, in that we fabricate the capsule from small molecular compounds, instead of polymers, that can crystallize.

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.