FUNPANE · The Synthesis and evaluation of Micro-engineered functional Particles from Nano-emulsions

Final Activity Report Summary - FUNPANE (The Synthesis and Evaluation of Micro-engineered Functional Particles from Nano-emulsions)

It is often valuable to encapsulate many functional materials (FM) used within the industry in a polymer shell. The encapsulation provides a mechanism to protect the FM and this can enhance their lifetime and use, with obvious benefits in terms of product lifetimes, cost efficiency and potential impact on the environment. For example, if a biocide is encapsulated within a polymer particle its release of this over the lifetime of a product can be delayed, thereby reducing the frequency of re-applying the product. This is beneficial to the consumer in terms of time and cost and, in addition, provides a potential reduction of the impact of the product on the environment through lower raw material demand. Another example is the use of titanium dioxide (TiO2) within coatings. TiO2 is used to provide hiding power or opacity, which is best achieved when TiO2 particles are well spaced and not aggregated. In a given formulation, in case the spacing is forced, it can allow for a reduction in the overall TiO2 level within a coating, resulting in a significant reduction in both cost and coating embodied carbon, since manufacture of TiO2 is an energy intensive process. This project addressed the encapsulation of functional materials within organic polymers via mini-emulsion polymerisation. The successful encapsulation of a functional material within a polymer matrix was shown to be dependent upon many factors, not least of which was the nature of the material itself. A significant learning from this project was that it was necessary to tailor the conditions of polymerisation and the recipe to a given FM, i.e. it was not possible to develop a ‘one-size-fits-all’ approach. This situation arose because of the differences in the surface nature of the given functional materials. For example, TiO2 had a relatively hydrophilic surface when compared to an organic yellow pigment, thus presenting quite different challenges when encapsulating these materials within a polymer matrix. The situation for organic molecules, e.g. fragrances, was much simpler and we successfully demonstrated encapsulation and release of fragrance from a mini-emulsion polymer. The main issue to be addressed in this case was whether the FM would interfere with the polymerisation process itself, meaning that there had to be careful choice of both the FM and the polymerisation process. For the encapsulation of particulates it was necessary to consider the stability of the FM within the monomer and polymer phases and the stabilisation of the overall polymer and FM particle. Our research within these three areas allowed us to develop recipes for the successful encapsulation of TiO2 and this was achieved while bearing in mind the constraints of making the process commercially viable. Many previous workers in this field had addressed encapsulation by considering low solids polymerisations and, whilst successful, these performed only at low solids, hence having little commercial importance. Our work provided unprecedented advances in the encapsulation technology at ‘high solids’. This was particularly challenging for the case of TiO2. In the application noted above, i.e. the spacing of TiO2 within a coating, it was necessary to achieve mono-encapsulation, i.e. one TiO2 particle within each polymer particle. During the development of successful approaches we experienced many failures, such as little or no encapsulation and multi-encapsulation. Both of these results were shown to have a detrimental effect on the scattering efficiency of TiO2 when formulated into a coating; it was hence necessary to pursue and achieve the goal of mono-encapsulation. This project provided unprecedented advances in encapsulation technology and generated significant understanding of this commercially important area. It was therefore anticipated to widen the potential exploitation of encapsulation for the production of high performance materials in many industries.

Data: CORDIS, © European Union