I started my PhD in November 2016 at the Chair of Functional Materials
at the Technical University of Munich. The focus of this chair is the investigation of responsive and functional polymer films and how the nanoscopic properties, meaning the structure and dynamics of these films on a nano (or molecular) scale, influence their macroscopic behavior e.g., their thickness, stiffness, conductivity, or absorption behavior. And only a few hours in, I already got my first hard deadline: Samples had to be ready in two days for experiments at the neutron research reactor FRM II
. This neutron source is located at the TUM campus, so at least no traveling was involved).
As a trained chemist, I had zero experience in preparing polymer film samples (which turned out to be quite a challenge for my polymer systems). I didn't know too much about neutron scattering techniques, and I knew nothing about how challenging neutron beamtimes can be. But still, I had everything I needed for these first tasks: Supportive and experienced colleagues! And that was already the first lesson I have been taught. No matter how big the challenge is, as a team you can do it.
In the end, it couldn't have started any better. Despite all the failures and frustration during the first days/weeks, these neutron experiments were the basis for my first posters, talks, and publications. Regarding the fact that someone else has written the proposal for the beamtime (who left the chair before doing these experiments), this was pure luck. And that is the second lesson, I have been taught, even though I didn't realize it back then: There is a lot of luck involved in your research. Being at the right location at the right time is plain luck. Or if you want to see it from another perspective: If something doesn't work out as planned, it might not be because of you, it might be because of bad luck (still sucks though).
So, let's talk about some science: As I mentioned earlier, I investigated polymers during my PhD. To be a bit more specific, I investigated diblock copolymers (DBC), which simply means a linear polymer (a long chain of repetitive subunits called monomers) that consists of two different blocks. Figure 1a gives you an impression of what these things look like. This polymer system didn't change too much during my PhD, so let me explain what's so special about it. One of the two polymer blocks (the black one) is a polysulfobetaine. I have written a Wikipedia article about this polymer class, which you can find here
. Polysulfobetaines (PSBs) are zwitterionic polymers, meaning they have some charged groups, while the overall charge is zero. The PSBs I used, have a negatively charged sulfonate group and a positively charged amine group. Figure 1b shows the chemical structure and where the charged groups are located. PSBs are quite useful and by now they are commercially applied as anti-fouling surfaces, ultrafiltration membranes, blood-contacting devices, and drug delivery materials.