What is it made of: Your scarf

Describing things from the natural world is always more challenging than describing man-made things, mostly because of the inherent variability and complexity in nature. After perhaps biting off more than I can chew with carrots, I’m stepping it down a notch. This week, I’m going to talk about what your store-bought winter scarf is probably made out of: acrylic fibre.

Alongside the natural fibres wool and cotton, acrylic fibre is one of the most common materials for warm winter clothes. Apart from its presence in ready-made clothes (like jumpers and cardigans) and accessories (like hats, gloves and scarves) found in clothes stores everywhere, acrylic is also one of the most popular fibres of yarn found in craft stores. It is a soft, lightweight fibre, which holds dye well and is very resistant to wear as well as washing.

In terms of its chemical composition, acrylic fibre is a fibrous polymer. A polymer is a large molecule made from several repeating units, which are called its monomers. It is common for commercial polymers to be made of more than one kind of monomer, as adding a percentage of different monomers can alter the properties of the entire polymer, such as giving it heat or wear resistance.

The chemical structure of acrylonitrile. Image source: https://commons.wikimedia.org

The primary monomer in acrylic fibre is acrylonitrile. The acrylonitrile content of acrylic fibre must be greater than 85%. Fibres with an acrylonitrile content of 35-85% are referred to as modacrylic fibres. Acrylonitrile, on the right, consists of two functional groups: vinyl (two carbons connected by a double bond) and nitrile (carbon and nitrogen connected by a triple bond). The vinyl group is what undergoes the reaction to polymerise this molecule into polyacrylate — acrylic fibre. The double bond between the carbon atoms is broken in favour of each of the carbon atoms forming a bond each with a different acrylonitrile molecule.

The structure of polyacrylonitrile. Image source: http://pslc.ws/

On the left is the structure of polyacrylonitrile, a polymer which consists entirely of the monomer acrylonitrile. The square brackets represent the repeating unit of the polymer, while the n represents the number of repeating units. This value is usually not a single number, but rather a range, as the length of polymer chains can be difficult to control precisely. As noted above, acrylonitrile is not the only monomer present in acrylic fibre, so the structure on the left is not entirely representative of its chemical structure — but as acrylic fibre should be at least 85% of this monomer, it is a fair approximation. The co-monomers used in the manufacture likely vary from manufacturer to manufacturer.

Acrylic fibre is found in everything from hats and gloves to carpets and upholstery to sweaters and cardigans. This material is testament to how versatile synthetic polymers can be — a far cry from the tough, hard stuff the word “plastic” evokes in our minds.

You can find me on Twitter as @Lady_Beaker, reach me via e-mail at chemistryintersection@gmail.com or by the comments down below.


Chemistry picture of the week: Sticky notes

20150806_152632Managing a chemistry PhD project is chaotic. On a day-to-day scale, in a synthetic project, there are three main tasks: to work up (complete) old reactions, to analyse their products and to set up new reactions. Even without any other considerations, these three tasks alone can spin out of hand when considering the volume of reactions we work with. As a PhD student, however, your job is not only to carry out your project, but to plan and manage it as well. We need to constantly analyse the data that we get and shift our goals and focus accordingly. It is extremely common to attain a result you weren’t even remotely aiming for, but that ends up being much more promising than any other results to date — and just like that, the focus of your project has changed.

There is also a delicate, difficult balancing act that goes to doing science on a deadline. With the strict three year time limit on our scholarships (in Australia), we need to be conscious of the months that go into pursuing an evasive, yet promising result. A thesis cannot solely be filled with a thousand things that were tried and did not work — and as I’ve mentioned before, there is no hope on Earth for publishing that kind of science. Thankfully, our supervisors will usually have had at least a number of PhD students before us, and will know the project and timeline to set in order to yield results for a thesis. To benefit from this knowledge, we must be sure to communicate with our supervisors readily if we feel we are banging our heads against a brick wall instead of doing useful work — not only may they know something new to try, but they are also better versed at saying when it is simply appropriate to abandon a project.

Another project management requirement for science projects are the rigorous experimental details we are expected to record. One of the main characteristics of science is that it is reproducible. In order for chemistry experiments to be reproducible, we need to record a number of details: what chemicals you used, what quantities, how long did the reaction go for, what was its appearance and so forth. We record these details into a handwritten lab book; analyses are usually filed separately. With a constantly shifting project focus, a lab book can quickly become disorganised. My lab book in particular deals in three-page spreads dedicated to the same “topic”, which, in my case, is usually a family of very similar reactions. These topics can then repeat later in the book, but are usually spaced by unrelated spreads. We try to work on a few different things at once, for variety and also for the likelihood that something will actually yield usable results.

All of this boils down to the need for extremely good organisational skills to keep abreast of the requirements, current status and future plans of one’s project. The lab notes are a solid friend to turn to when in doubt, because there one will most easily note the experiments that have worked and that haven’t. It is not particularly helpful for the planning of one’s project, however, since the lab book is reserved for experimental details. For to-do lists, lists of samples that need analysing, ideas for new reactions and helpful advice from group members or supervisors, I use sticky notes. Sticky notes are lovely as reminders and place holders, even catalogues — and they can be stuck to any surface! They are ephemereal, and yet a little more permanent than hastily written notes on the back of your disposable glove. Planning a PhD project somehow feels much more friendly and manageable when you do it one colourful sticky note at a time.

If you have any ideas on project management, feel free to contact me in the comments, at chemistryintersection@gmail.com. Alternatively, tweet me @Lady_Beaker.

Demonstrator’s vow

For those not in the know, or for those whose universities operate differently to those in Australia, chemistry postgraduate students here from Honours to PhD get the chance to teach undergraduates in a small capacity. During a chemistry major, alongside lectures and tutorials, undergraduates undergo a certain amount of lab work in small groups (15-20 students) supervised by a postgraduate student. This postgraduate student is called the “demonstrator,” because their role is primarily to demonstrate proper laboratory technique and etiquette. For the postgraduate student, this usually gives a small income stream to supplement our scholarships and also gives us teaching experience, crucial for those seeking to further themselves in academia.

At this point, I have demonstrated for two classes, one in each semester of my Honours year last year. It is the beginning of second semester here at the University of Melbourne now, and I have been assigned my first first year class at this university. As I prepare, I reflect back on my successes and failures last year. To my shame, I have to admit that there are more of the latter than there are of the former. Especially as my Honours year drew to a close, I let my stress and exhaustion bleed into the teaching labs and I’m afraid I wasn’t as good of a teacher as I could have been. To right this, and to honour all the amazing chemistry teachers I have had in school and in university, I wanted to devise a sort of code of honour — a vow — to guide myself and other potential demonstrators in the coming semester.

As a demonstrator, I vow that:

  • I will convey my love and enthusiasm for chemistry in every move I make in the teaching laboratories. I will endeavour to make the students’ experience a positive one so they may be encouraged to return in later years.
  • I will prepare well for the lesson beforehand and know all the material front, back and sideways. Confidence in the material should instil the students’ confidence in me.
  • I will try to provide a broader context for all practicals, especially the boring, repetitive ones. I will emphasise that chemistry is still primarily an experimental science and learning practical skills is learning chemistry.
  • I will be an unyielding enforcer of safety rules in the laboratory.
  • I will dig deep for a fountain of patience, remembering how nervous I was in my first year practicals. I will not be visibly annoyed at repetitive questions or silly mistakes. Although it goes against everything I stand for on this Earth, I will make a mighty effort to resist the constant urge to snark.
  • I will guide my students to the correct answers — without spoon-feeding them — by encouraging them to think like chemists.
  • I will mark reports fairly but stick to my guns if students question my marking. I will try to provide positive feedback and help my students grow. I will not shame them for their mistakes, even in writing.
  • I will be patient with my unpaid free time, which will inevitably be consumed in the duties of demonstrating, like class preparation, report marking and slow students finishing in the lab. Demonstrating takes up so little of the year — there will be other weeks for other things.

If any veteran demonstrators have wisdom to add to this list, I would be more than happy to hear about it. Perhaps even more importantly, if you are a current undergraduate and either love or hate something your demonstrator does, let me — us — know; we’re still learning, too.

You can contact me at chemistryintersection@gmail.com, in the comments or find me on Twitter as @Lady_Beaker, tweeting about my chemistry life.

Chemistry picture of the week: Vials

Last week’s chemistry picture is a little late due to a short vacation I’ve just returned from. As an apology, I’ve included a little picture from my vacation at the end of this post. Hope you enjoy!20150729_165505

I currently work in the field of metallosupramolecular chemistry. Supramolecular chemistry in general deals with the chemistry beyond (“supra”) the molecule — with interactions between molecules in larger assemblies. “Metallo” simply refers to our preference to direct and design our supramolecular chemistry by use of bonds between metal ions and organic molecules we call ligands. An aim of supramolecular chemistry is to design complex aggregates that are difficult to access by molecule-focused chemistry. Instead of the step-by-step method employed by many synthetic chemists, we rely upon self-assembly. This is pretty much exactly what it sounds like: we, the chemists, provide the starting materials and the right conditions, and the forces of nature do the rest. From relatively simple starting materials, we can then generate (relatively) huge, complex assemblies within days or weeks that would take months by step-by-step synthesis.

The problem with this is the unpredictability of nature. As much as we would love for chemistry to work out the way we want it to every time — just as with life — it often doesn’t. The exact interactions between our metal ions and ligands can be very difficult to predict because of the number of possibilities that exist for self-assembled compounds. There are often at least a handful of different results accessible with very small variation in reaction conditions — and others that we may not know of because of their energetically unfavourable nature. We may know what exactly we are targeting, but we almost always have to do a significant amount of fine-tuning before we ever get there: everything from trying different metals, subtly different ligands, solvents, counter-ions, crystallisation techniques and so forth. Even if there are only two components in the reaction mixture, the ligand and metal, the possibilities for trial are still numerous. The more variables you add, the more difficult your job of fine-tuning your system becomes.

The way we deal with this is to simply run as many attempts of different variations of the conditions as possible. This is where the vials come in. Many people are aware of the classic chemistry glassware: conical flasks, beakers and test tubes, for some. In our lab, though, the star of the show is the simple glass vial. Glass vials are inexpensive, so they are plentiful even in a lab full of glassware-hoarders. We can conduct even tens of experiments at a time and nobody is going to grumble about it. Because of their costlessness, they are also essentially disposable if a crystallisation attempt goes awry and the residue can’t be cleaned off. They are small (the ones pictured only take up to 10 mL of solvent), so milligram scale experiments — which we conduct regularly — are feasible. Their small size also means we can hide them in a cupboard for a year so that those more difficult to access compounds can form while we completely forget about them.

In my opinion, there is no better friend for the metallosupramolecular chemist than the glass vial — except maybe the x-ray diffractometer, but that is a different story altogether.

You can contact me in the comments, via e-mail at chemistryintersection@gmail.com or find me on Twitter as @Lady_Beaker, where I tweet about the daily life of a PhD student in chemistry.

And now, here is the picture from my trip I promised:


Taken from a moving car in Victoria, Australia driving toward Melbourne from Mount Hotham.