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By David Calvert, June 2017

It has been a strange last couple of years in global politics, and while the question “just what on Earth is going on?” may have been used in relation to Brexit, the US election, the latest UK election or Leicester City winning the English Premier League, it is still a question which as formulators we continue to ask ourselves. Whether it be changing viscosity, phase separation, product crystallising out or the product simply not working, the answer can often be found in a poorly thought out, or rushed, formulation design.

The solution to this often lies in using a formalised design process for the formulation which starts well before you actually commence your practical work. A quantified definition of what you are actually promising your customer, the competitive IP situation and essential cost and regulatory constraints are among the factors you need to consider at the onset.

Following this initial, essential preparation you commence your laboratory work where you are likely to need an experimental design approach in order to flush out the key components of your formulation, including almost certainly interactions between components. You will also need to define a preliminary manufacturing process, similarly with a definition of its key elements.

With a good laboratory programme behind you, you move to pilot stage, where you encounter scale-up issues such as mixing, heat transfer, dead-spots, cleaning and avoidance of contamination. You may have already sampled a customer with your product and could widen your product sampling at this stage.

If all progresses well, then the transfer to manufacture occurs. Ideally you will have consulted with your manufacturing colleagues well before this stage, rather than this being the first time they have heard they need a novel mixer, or a large scale “spatula”. Here you will understand what are the critical elements of the process are and what control strategies you envisage.

With successful manufacture, you then reap the benefits of all the hard work and can use the knowledge gained to go forward and develop your next range of products.

Risk assessments form an essential element of the “stage-gate” type approach to development that you will need to take. As you move through the process and the risks should be better defined and reduced, the closer you get to production and commercialisation.

We call this systematic approach “Design for Formulation” and if you want to learn more, we are running a two day training workshop at Jury’s Inn Hotel, East Midlands Airport, in the UK on September 19^th and 20^th. You will hear from experienced practitioners such as our Associate Partner Ian Jolliffe, David Hood from the Excellence Partnership, Phil Threlfall-Holmes of TH Collaborative Innovation (THCi) and Olivier Cloarec of Sartorius-Stedim.

There are two webinars available where you can hear David and Ian talk about different elements of the process. Follow the links below – and send an e-mail to info@iformulate.biz if you require passwords.

– iFormulate introduces…Ian Jolliffe on “Design for Formulation”

– iFormulate introduces…Process Control and Formulation

Details about the course and how to register before the August 1^st early bird deadline can be found on the event web page.

By Jim Bullock, April 2017

Small can be beautiful of course but sometimes events can improve while they grow in size. The fourth “Spray Drying and Atomisation of Formulations” course, hosted by the University of Leeds, is a case in point. Starting in 2014 with around twenty delegates and two days of content, the course is now three days in length with over twenty presentations, six laboratory demonstrations, seventeen lecturers (from industry and academia), sixty delegates and one ever-popular course dinner. Each year I am impressed by how many new applications for spray drying are discussed, either in the formal sessions or during the informal opportunities to talk.

In 2017, delegates came from all parts of Europe and some from further afield. There was a big contingent from the pharmaceutical industry (where spray drying is really gaining a foothold for a number of uses) as well as from food & drink (think infant formula milk), speciality chemicals, agrochemicals, detergents and ceramics.

Although the science of spray drying is well understood, during the panel sessions, the expert lecturers were of the opinion that progress can still be made in predictive modelling and in-process analytics. Challenges still remain in energy recovery and (for pharmaceuticals) to make the technique a more universal alternative to freeze drying.

As ever, thanks should go to the energetic organisational support from the CPD team at the University of Leeds Faculty of Engineering who have had to deal with an increasingly complex course over the years. The 2017 course was sold out, so to make sure you don’t miss out in 2018, have a look at the course web-page and then – to express an interest in attending – please email cpd@engineering.leeds.ac.uk.

By Jim Bullock, April 2017

Having helped to organise and promote HSP50, I expected it to be a special event but I don’t think I realised how special it would be until it actually started.

This image, taken at the Grand Conference dinner at the National Railway Museum in York, shows five of the leaders in solubility theory and practice. From left to right, Prof Steven Abbott (HSPiP), Prof Jean-Marie Aubry (U. Lille), Dr Hiroshi Yamamoto (HSPiP), Dr Charles Hansen (HSPiP) and Prof Andreas Klamt (COSMOlogic). Image from https://www.hansen-solubility.com/conference.php/.

HSP50 was a special conference organised to celebrate fifty years of Hansen Solubility Parameters (HSP). HSP were first developed and described by Dr Charles Hansen in his PhD thesis in 1967 and have since been adopted by industrialists the world over as highly practical tools to assist formulation optimisation. So it was great to see such a diverse range of nationalities and organisations represented at the conference which was co-hosted and supported by the Green Chemistry Centre of Excellence at the University of York.

Applications of HSP are hugely varied and we had excellent contributions on topics as diverse as solvent design, prediction of environmental hazards, organic photovoltaics, paint strippers, supercritical fluid extraction processing, dye delivery, prediction of eye irritation, the stability of nanodispersions, packaging and many more. Some well known names were amongst the attending companies (e.g. Croda, Solvay, Chanel, Lilly, P&G, ExxonMobil, Afton, Henkel, Schott, Agfa and Shell) and universities were also represented (e.g. Lille, Poznan, Nottingham, U.Mass Lowell, Montreal, Erlangen-Nürnberg and Karlstad).

But for me the real highlights were first of all the sense of a community coming together for the first time (amazingly this was the first ever HSP conference) with a real willingness to share experiences but most importantly the tremendous reception given by the attendees to a clearly emotional Charles Hansen as he gave his keynote address on the first day.

A huge amount of credit should be given to Professor Steven Abbott of the HSPiP team (which also includes Charles Hansen and Hiroshi Yamamoto) who not only gave a great HSP tutorial before official proceedings started but crucially inspired the conference and cajoled everyone relentlessly until it happened. Many thanks are also due to the able team from the University of York GCCE for their organisational support before the event and on the day.

In case you missed out on HSP50 and would like to learn more about the topic, you can start by looking at the recording of our webinar on HSP50 or see background information on the HSPiP website.

By David Calvert, April 2017

I recently attended the 5^th QbD Symposium organised by De Montfort University and was struck by two recurring themes throughout the day.

The first – and more technical element – was how much emphasis the pharmaceutical community is placing on continuous processing and in particular the use of hot melt extrusion. As many of you will know, the use of hot melt extrusion can be of value when you are looking to formulate poorly aqueous soluble materials. By using the process to disperse the active ingredient in a solid polymer matrix you produce a “solid dispersion” which can then be made into a dosage form such as a tablet which can then be taken by the patient. As the polymer dissolves in the gut the active is then released to do its work in the right quantity in the right place. Of course this “sophisticated” pharmaceutical process has its origins in the more industrial sphere of plastics processing which does go to show how much value there is in looking outside of your own industry to look for a solution to your formulation problem. You can read more about the application of Open Innovation in the pharmaceutical and healthcare sector by requesting our white paper on the subject here.

My other thought from the symposium was how much De Montfort University is doing to secure the future of pharmaceutical formulation. We often bemoan the lack of training in the science sector but this is a case where De Montfort – and Dr Walkiria Schlindwein in particular – should be warmly applauded. A number of the speakers at the two symposia I have joined have gone through the MSc either full time or part-time via distance learning and all have been employed by significant players in the pharmaceutical sector. They all have an enthusiasm for the practice of Quality by Design and through this were able to demonstrate how this can result in shorter development times, improved products and increased yields.

Of course the benefits of a structured approach to design for formulation is not just restricted to the pharmaceutical sector and if you would like to reap the benefits of this approach in your sector, then you should consider attending our two day training course Design for Formulation which takes place on September 19th and 20th this year. You can find details of the course and how to register on our web-site and we also have available a recording of a webinar given by Ian Jolliffe, the lead trainer on the course, on issues to consider before you go into the lab. For any enquiries please contact us on info@iformulate.biz.

By David Calvert, April 2017

The in-cosmetics exhibition started in 1990 at the Birmingham NEC and from humble beginnings, with around 80 exhibitors and 900 visitors, it  has grown into the behemoth that had 780 exhibitors and close on 9000 visitors on its return to London this year after a 15 year absence.

I was one of those 9000 this year and there was certainly enough to fully occupy my day purely with the exhibitors, so I had no time to listen to one of the many presentations and technical seminars that were organised.

As you would expect, the word natural was present on a large number of the exhibitors’ stands and there were a large number of them promoting new and natural preservatives for cosmetics. Lots of natural oils with their many claims, but I also noticed that some formulation technologies familiar from other industries were present to some degree. These included encapsulation, high throughput experimentation equipment and novel extraction technologies.

There was so much to take in at the show that any conclusions about trends and new products can only represent a snapshot of my own personal experience. I was intrigued by the number of “anti-pollution” products being promoted and since the show I have looked into this further. A blog article from 2016 published by Euromonitor is well worth a read if you are interested in learning more. I am unsure as to how many of these new products are simply repackaged or repositioned skin protection products and how many are actually new and developed specifically for this feature, but there is no doubt that the topic is gaining traction.

Staying with the new and exotic, a few years ago hyaluronic acid and its derivatives were being promoted extensively for their anti-ageing properties but did seem to be struggling to make an impact, be that due to price, or lack of a market need. The new drive towards “anti-pollution” products does seem to have given it a new lease of life however and many exhibitors products were based on hyaluronic acid or some of its derivatives. If you are interested in learning more, just enter “hyaluronic acid and pollution” into your favourite search engine and you will get a large number of hits.

So as with many of these exhibitions, the question is was it worth going? Well despite my shoulder aching from carrying all the literature and my feet burning up from walking more than 10000 steps in the exhibition hall alone, I did find it a valuable exercise. Next year it will be held in Amsterdam and my request to potential exhibitors is to look for cosmetic ingredients which can be used in products applied to combat “exhibition feet”!

By David Calvert, January 2017

The political turmoil of last year including Brexit and the election of Donald Trump to be the 45^th President of the United States made for a lot of speculation as to the impact of these dramatic changes and of course has provided satire shows with material for at least the next four years.

As 2017 starts though we can start to see some of the realities of these decisions and this made me wonder about how this could impact on the work of formulators. The regulatory landscape is key in driving many of the new formulations, whether these be lowering volatile organic compounds (VOC) emissions, restricting the use of certain chemicals due to REACh regulations or developing formulations with a lower carbon footprint.

This latter is not necessarily driven by specific regulations but more responding to initiatives like the various Climate Change Agreements such as Kyoto or Paris. In some cases the move towards lowering carbon footprint in its various guises is driven by a desire to demonstrate Corporate Social Responsibility (CSR). Some of the major FMCG companies such as RB, Proctor and Gamble and Unilever have placed sustainability high on their agenda.

In their 2015 Sustainability Report RB have a target going forward to reduce the CO2 footprint of their products by one third by 2020 and reduce the CO2 emissions from their manufacturing by 40% before 2020.

P&G have a similar commitment and in their 2015 sustainability objectives  state that they are focusing their efforts in the following areas:

“(1) Reducing the intensity of greenhouse gas emissions (GHG) from our own operations through:

Driving energy efficiency measures throughout our facilities

Transitioning fuel sources toward cleaner alternatives

Driving more energy-efficient modes of transporting finished products to our customers

(2) Helping consumers to reduce their own GHG emissions through the use of our products via:

Product and packaging innovations that enable more efficient consumer product use and energy consumption

Consumer education to reduce GHG emissions such as the benefits of using cold water for machine washing

(3) Partnering with external stakeholders to reduce greenhouse gas emissions in our supply chain, including:

Ensuring our sourcing of renewable commodities does not contribute to deforestation

Developing renewable material replacements for petroleum derived raw materials”

Unilever launched their Sustainable Living Plan in 2010 as their blueprint for sustainable business and have stated that they wish to decouple their growth from their environmental impact.  As part of this, they are aiming to reduce their environmental impact by 50% by 2030 and this includes a target to be carbon positive in manufacturing by 2030 by saving 1 million tonnes of CO2.

So how will all of this be changed by the potential appointment of Scott Pruitt to be the new head of the Environmental Protection Agency (EPA) in the USA? For those of you who are not aware of Scott Pruitt, he has served as Oklahoma’s attorney general since 2011 and is presently representing the state in a lawsuit against the EPA to halt the clean power plan. Pruitt is a well-known climate change sceptic who has cast doubt on the evidence that human activity is causing the planet to warm.  At time of writing the confirmation hearing for Scott Pruitt has just taken place and barring some startling revelation it is likely he will become the new EPA head. We will have to see if he does introduce measures to reduce restriction on fossil fuels in the US and whether some of the companies change their approach to sustainability. My own personal view is that the approach of the companies mentioned will not change but perhaps the pace of change will be reduced somewhat and focus outside of the US.

If the EPA then introduces measures which “relax” regulation on other emissions such as those to water, will this mean that agrochemical formulations will be easier to develop? Is this good news for formulators? A new approach to some of the pressure groups who cast doubt on any scientific findings may well be refreshing if the pressure to remove some agrochemical actives from the market is reduced but we will have to wait and see. On a similar vein, the former Chief Executive of the Crop Protection Association in the UK stated in a letter to the Financial Times in December 2016 that he hoped the UK would “lead the way in striking a sensible balance between protecting and enhancing the environment and at the same time, supporting UK farmers to provide a healthy, safe, reliable and affordable food supply”

Staying with Brexit, I feel that change will be slower and any impact will be unlikely to be seen until at least two years after Article 50 is triggered. There remains the possibility that the UK’s exit could lead to yet more regulations for formulators to comply with, although it is hoped that common sense will prevail and the majority of the European regulations will simply be “ported over”. Putting the case forward for the UK to change the regulatory landscape the President of the British Crop Protection Council argued this month for the UK post-Brexit to move closer to the US EPA risk-based approach. He argued for the removal of the “EU’s unscientific hazard based assessments and the associated Candidates for Substitution and Comparative assessment processes”.

Whether the UK can afford to implement its own new regulatory approach may be more is another question and the whole issue may be decided more by politics than the practical aspects.

I guess my conclusion from compiling this article is that formulators – like everyone else – will be affected by the political turmoil of 2016 but how and whether this is positive cannot be determined as yet. All we can do as they say is “wait and see” and be quick to adapt once clarity is there, if that is ever the case!

With Daniel Schmidt of the University of Massachusetts Lowell

Formulators in all industries are increasingly being charged with finding new ways to reduce the environmental impact of formulated products as well as to eliminate hazardous components. The formulator is faced with a variety of conflicting factors when carrying out such reformulation so the ability to use practical tools with sound scientific basis can be decisive.

Among the talks to be given at the upcoming HSP50 conference (York, UK, 5-7 April 2017), Prof. Daniel F. Schmidt of the Department of Plastics Engineering at the University of Massachusetts Lowell (UML) will present an overview of work being carried out by multiple researchers at his institution involving the use of Hansen Solubility Parameters (HSPs) and provide examples of a number of successes as well as opportunities for further development.

Most generally, the efforts at UML and the affiliated Massachusetts Toxics Use Reduction Institute (TURI) fall into two broad categories: searching for alternatives to existing formulations and predicting the compositions of new formulations. In the former case, many efforts have been driven by a desire to identify greener, more sustainable solutions to existing problems and to address increasing regulatory pressure on volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). In the latter case, the motivation is to save time, effort, and materials and reduce the number of experiments needed to identify new, useful formulations.

Daniel Schmidt takes up the story:

“One example of work to identify alternative formulations is the replacement of methylene chloride in a gel-based paint stripper formulation. Due to increasing regulatory pressure, such formulations are less and less acceptable, but existing alternatives have major performance issues as compared to methylene chloride based strippers. The use of the HSP approach made it possible to identify a blend providing excellent performance while addressing regulatory concerns. A similar story will be presented concerning the replacement of aromatic hydrocarbon solvents in a contact adhesive formulation. Concerns over HAPs drove our industrial partners to search for alternatives; the HSP approach, coupled with optimization software enabling the evaluation of more complex blends and the use of cost as a selection parameter, yielded formulations meeting environmental and cost targets. In both cases, our research team found that the existing formulations in use by industry were themselves suboptimal. This result emphasizes that even in those cases where solvent replacement is not necessary, opportunities exist to enhance performance via a thorough assessment of materials already in use.

In addition to solvent replacement, researchers at UML have also used the HSP approach in service of a project concerning styrene replacement in vinyl ester resins, with concerns over VOCs and associated regulatory pressure once more driving the work. Also related to concerns over sustainability, HSP calculations were used to identify greener solvents for two stubbornly insoluble polymers: poly(3-hexylthiophene) (P3HT), an active material in organic optoelectronics, and poly(butylene succinate) (PBS), a biodegradable replacement for materials like low-density polyethylene. In the latter case, it was further shown that copolymerization broadens the range of solubility for a family of PBS-based renewable co-polyesters. Attempts to identify bio-derived solvents for polystyrene foam recycling have been made with support from the HSP model, and TURI has compiled a large database of safer molecules that is now included with the Hansen Solubility Parameters in Practice software package to further their goal of seeing toxic substances phased out in favor of more sustainable and practical alternatives. TURI’s Cleaning Laboratory is making use of this approach as well, given that demand for this type of support is only increasing over time. As an example, another problem recently identified in which the HSP approach promises to provide assistance is to guide formulators in identification of a replacement for methanol in windshield washer fluid.

In addition to the aforementioned efforts to identify alternative formulations, several attempts at compatibility prediction in new compositions of matter have been carried out.  In one example, predictions were made concerning the compatibility of a new class of small molecule biofilm inhibitors with various grades of plastics used in medical device applications, as well as solvents used to process these small molecules in this context. The ability to perform such predictions was critical to the success of the work, given that the small molecules were custom-synthesized and available only in very small quantities. In a second project, the HSP approach was used to guide solvent selection for a series of never before studied high-impact co-polyesters. While here the level of success was more limited, this effort nevertheless highlights one of the opportunities for improving the predictive power of this approach. Related to such efforts, ongoing discussions involving how best to define HSP values for heterogeneous entities such as surface-modified clay nanoparticles promise to yield results of significance to both science and industry moving forward.

In sum, a broad range of exciting work has been and is being enabled thanks to the use of the HSP approach by researchers at UML and TURI. These efforts range from improving the processing of novel materials in support of fundamental research concerning their behavior to the solution of pressing industrial problems involving solvent replacement, VOC and HAP reduction, and improvements in safety and sustainability more generally. While challenges remain and not all efforts result in success, these efforts demonstrate that there are clear opportunities to utilize the HSP model to make progress on problems of real importance to researchers in academia and industry, and to further extend this approach so that today’s difficulties become tomorrow’s successes.”

We hope that this item has given you an insight into how the HSP approach can be used to help reformulate industrial products and we look forward to seeing you in York in April 2017.

With Dietmar Lerche of LUM GmbH

Devices based on quantum dots and smart nanoparticles are currently getting a lot of attention. For instance, the colours, contrast and brightness of displays based on quantum dots provide benefits for users of TVs and phones. In addition, such particles can create value when incorporated into novel materials. So, smart particles can be designed to respond to light or magnetic fields, or can be used as carriers to deliver medicines in a targeted manner.

Numerous methods have been developed to design nanoparticles and new particles are appearing all the time. However it’s especially important to ensure that the particles produced are stable in their intended use. Unfortunately it’s not always obvious how the particles are going to interact with the other materials such as polymers, dispersants or solvents which form part of the product formulation.

Dietmar Lerche of LUM GmBH is a speaker at the HSP50 conference in April 2017. He takes up the story:

“In order to tackle the challenges of compatibility and stability of particles, we took a look at the approach developed by Charles Hansen fifty years ago. Put simply, Hansen’s approach turns the chemist’s well-known rule of thumb, “like dissolves like” into a quantitative and predictive system that allows solvents and solutes to be matched to each other. We had seen that nanoparticles (or in effect their surfaces) could also be assigned their own set of Hansen Solubility Parameters (HSP). Then the stability of particles (estimated by sedimentation velocity) could be predicted by looking at the extent of compatibility with the solvent medium, as described by the HSP of that medium. In other words “like is compatible with like”.

However, observing sedimentation with the naked eye is a tedious process, because under normal gravity it can be very slow and can take weeks to obtain a ranking of sedimentation velocity. So when I read an article about the characterisation of carbon black by HSP, something clicked. Why not combine our STEP-Technology® with multi-sample analytical photocentrifugation? This system effectively uses centrifugation to accelerate the sedimentation process. Furthermore because our LUMiSizer® has a multi-sample capability, twelve different solvents can be tested at the same time and a full set of 48 test solvents, as originally proposed by Charles Hansen, can be compared in about a half day. 

We started by looking at industrial pigment particles in our application lab and we devised a classification scheme for the relative sedimentation time of the particles in different solvents, which took into account the density and viscosity of the solvents. Once we had entered the sedimentation scores into the HSPiP software we obtained some promising HSP values for the particles. [D.Lerche, S. Horvath, T. Sobisch, Efficient instrument based determination of the Hansen Solubility Parameters for talc-based pigment particles by multisample analytical centrifugation: Zero to One Scoring Dispersion Letters  6, 2015, 5]

Following the award of an R&D grant from the German Ministry of Economics and Energy, we began some work with the Institute of Particle Technology at the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) in Germany (headed by Prof. W. Peukert). This allowed us to access the necessary nanoparticle know-how and technology so we could look at carbon black more closely as well as fine tune the sedimentation scoring scheme. We found that we could reproducibly determine the HSP of the particles (independently in Erlangen and in Berlin) as well as differentiate between different industrial grades of carbon black. We were also able to show that the dispersing process influences the carbon black particle surface and that this can be quantified experimentally by using HSP.

Then we took a look at quantum dots made from zinc oxide (ZnO) particles with a mean size of just a few nanometres. Particles such as these have potential to be applied in new optoelectronic devices, in sensors or as UV-blockers. A knowledge of how particles interact in different solvents is essential when optimising the conditions in specific applications.

Based on the dispersion process and measurement procedures we derived, again by using analytical centrifugation with the LUMiSizer®, for the first time HSP values for synthesised ZnO nanoparticles. In addition, the function and surface properties of ZnO particles can be tailored by the adsorption of different organic ligands at the particle surface. Thus, we modified the surface chemistry of ZnO quantum dots in this way and found that the polar ligands are made an increased polar contribution to the HSP values measured.

Because HSP values are very sensitive to the different ligands bound at the surface, HSP determination is a highly effective method to quantify the surface properties of colloidal particles. Thus an approach using HSP data can be used to help custom-build specific functionalities of nanoparticles and nanomaterials.

We are looking forward to participating actively in the HSP50 conference and hope to learn more about the developing science of Hansen Solubility Parameters as well as about growing applications all over the world.”

Prof. Dr. Dietmar Lerche

CEO, LUM GmbH, Berlin, Germany

We’re always impressed at how established methods like Hansen Solubility Parameters (HSP) can be not only used but also improved to solve new problems in industry. Below in the latest item in our series of items focusing on the upcoming HSP50 conference, Stefan Langner of the University of Erlangen-Nuremberg tells us about how HSP can be used to help produce formulations of advanced electronic materials.

If you’d like to keep up to date with the latest developments in solubility, solvation and the uses of HSP in formulation then you’ll benefit from attending HSP50, to be held at the University of York from April 5^th-7^th 2017. Registration is now open, just follow the links from our webpage.

We’re pleased to say that Stefan Langner is one of the keynote speakers at HSP50 and he’s looking forward to meeting fellow members of the community during the many opportunities for networking discussions during the conference.

“When you are working on advanced organic electronics using novel materials such as conducting polymers there are many challenges along the way. One of these is to solubilise these complex molecules. So if you find that, say, chlorobenzene does a good job, why not carry on using it during development?

That was the case for organic photovoltaics (OPV) and it took a while before the issue of production scale-up started to be significant for us. It was only then that we discovered that you can’t use chlorobenzene in most practical coating machines.

Another challenge for OPV was to get controlled phase separation of some of the key components. This could easily be achieved by some minutes annealing in an oven. But again, this simply could not scale up for production. What was needed was a solvent blend that would “force” phase separation within the production drying oven.

And finally for OPV, coatings are invariably multi-layer so a solvent which is perfect for one layer might, during coating, destroy a previous layer.

In all three cases, the problem could perhaps be solved with gut feel or trial and error. But these aren’t effective or efficient approaches when dealing with expensive materials and complex multi-layer products. So, instead, we needed a rational approach to controlling solubility. There are many fine solubility theories out there, but they are often difficult to apply to the complex materials used in OPV. Therefore, as part of one of the leading teams in OPV formulations working under Professor Brabec in Erlangen-Nuremberg, we decided to adopt a powerful but pragmatic approach using Hansen Solubility Parameters (HSP). We discovered that a key technique for measuring HSP, although useful, was rather too difficult to apply in our systems as it involved handling 15 to 20 sometimes unpleasant solvents. Instead, working with one of the authors of the HSPiP software, Prof. Steven Abbott, we developed a “grid” technique which created a rational range of solvents by mixing a few carefully-selected solvents in controlled proportions.

This “grid” technique has now spread to other areas of formulation and is a key feature of the HSPiP software. With our measured values of the HSP values for the key components, we could then start to successfully create rational solvent blends to replace chlorobenzene for production, to control phase separation (by ensuring that one “good” solvent for a key component evaporated quickly, forcing that component to separate out of solution), and to arrange for solvent blends that provided good enough solubility for one layer without disturbing a previous layer.”

 Stefan Langner 2016

Reference:

“Determination of the P3HT:PCBM solubility parameters via a binary solvent gradient method: Impact of solubility on the photovoltaic performance”, Florian Machui, Stefan Langner, Xiangdong Zhu, Steven Abbott, Christoph J.Brabec, Solar Energy Materials & Solar Cells 100 (2012) 138–146

Programming temporal shapeshifting Xiaobo Hu, Jing Zhou, Mohammad Vatankhah-Varnosfaderani, William F. M. Daniel, Qiaoxi Li, Aleksandr P. Zhushma, Andrey V. Dobrynin & Sergei S. Sheiko Nature Communications 7, Article number: 12919 doi:10.1038/ncomms12919

This is the answer to a number of everyday questions. For example:

• When will England win the football world cup?
• When will Boris Johnson make a fool of himself?
• When will this article get to the point?

Well one of the holy grails of formulation technology is the ability to deliver an active ingredient to a specific target in a specific place at a specific time. For example, many pharmaceutical products need to survive the passage through the acidic environment in the human gut, seed coatings may need to release an active ingredient when germination starts, materials such as cement may need to flow for a certain period of time and then set.

Time is however not the primary controlling factor in the formulation technologies used at present. Instead there are often external triggers such as pH, light, or temperature which are intended to act at a certain time. However I came across an article recently however which could change this and make time a direct controlling factor. In a paper in Nature Communications, researchers from the Universities of North Carolina and Akron have published work that they entitled “Programming Temporal Shapeshifting”.

From this rather convoluted title, they have outlined how they can make materials in the form of dual network hydrogels which will change shape after a specific period of time from seconds up to hours. They do this by having covalent crosslinks in the first network which provide elastic energy storage and temporary hydrogen bonds in the second network which regulate the energy release rate. These hydrogen bonds can then be reversed, which means the rate and pathway of a shape transformation can be encoded in the material without any external stimulus or trigger.

Obviously this work is in its early stages but the potential to truly time the release of an active, or even multiple deliveries does bring tremendous opportunities not just in the pharmaceutical sector. So those days of searching for a pH, heat, or light trigger may be a thing of the past and it will really be just a matter of time…

David Calvert, October 2016

At iFormulate our clients we frequently ask us to find and evaluate new technologies of potential interest and use to them. We can do this by keeping abreast of a wide variety of technical developments. If you think we might be able to help you then contact us on info@iformulate.biz or take a look at our website www.iformulate.biz.