Polymer encapsulation and moisture management

Discoveries about the interaction of polymers with surface structures have resulted in innovative products such as easily removable and programmable drug release chewing gums.

Research led by Professor Terence Cosgrove at the School of Chemistry has brought new insights into why polymers stick to or are repelled from surfaces. This new knowledge has been commercialised by Revolymer, a spin-off company that employs more than 30 people and whose products are used in a broad range of industrial and consumer applications.

Professor Cosgrove and his team developed new polymers that can be used in both hydrophilic (dissolvable in water) and hydrophobic (not dissolve in water) environments, a property that proved to be useful for encapsulation and moisture management in a variety of products.

“We were investigating the basic phase behaviour of polymeric systems when we realised that a new range of opportunities existed for comb copolymers that could be made easily by a novel non-solvent route and could be used in a range of personal care and food applications,” said Cosgrove. “We looked for applications for these new polymers and decided to investigate adhesion in chewing gums and the delivery of pharmaceutical actives and flavours.”

Biodegradable chewing gum

After 10 years of development, the first ever easily removable and physically degradable chewing gum was released in 2010. An environmentally friendly product, the chewing gum can be removed readily from clothes using soap and water, and tests have shown that more than 50% can be removed by conventional street cleaning. Any gum washed into the drains will degrade into minerals, biodegradable products and inert materials.

 “According to DEFRA, the annual cost of cleaning England’s streets has been estimated at £780m with more than £150m of that coming from the costs of removing chewing gum. With the new gum, this figure could be reduced by up to 70%.” - Prof Terence Cosgrove

“It was a dream come true to see academic research result in a real commercial product,” said Cosgrove. “Even more exciting was the knowledge that there were many more novel products in the pipeline.”

Today, Revolymer is floated on the AIM stock exchange and valued at £23 million. It employs a highly-qualified staff of 30 people in a state-of-the-art technical centre in North Wales. As well as the removable, degradable chewing gum which has excellent flavour and chew characteristics, the company has also developed nicotine and caffeine gums and has innovations in cosmetics, detergents, adhesives and personal care.

Encapsulation and moisture management

The company’s products are based on two key areas of technology developed at the University of Bristol: encapsulation and moisture management.

Encapsulation is a process whereby one, usually chemically or biochemically, active substance is confined within a second responsive barrier coating, protecting and stabilising the active substance, or ‘active’, from an environment that it might otherwise react with, particularly when in a liquid formulation. Revolymer’s technology is designed to release the active upon certain specific external stimuli or triggers, such as dilution with water (which can alter the pH and ionic strength of the formulation), and/or temperature change. The active substance is then released into solution, making it available to fulfil its function.

In the area of moisture management Revolymer has developed a range of novel proprietary amphiphilic graft copolymers such as Rev7®, whereby a backbone of hydrophobic polymer is covalently bonded with side chains of hydrophilic polymers to create a large repeating polymeric structure.

By coupling these two contrasting properties either side of the polymer backbone the copolymer is able to molecularly wrap materials mixed with it variously to increase their compatibility with water (e.g. reducing adhesion) or oil (e.g. surface modification). The company is able to modify both the backbone and/or the side chains of the graft copolymer to create additional novel polymers with tailored properties in order to address the specific requirements of a particular product.

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