Report on DEIS Summer School, June 2015

A Breakthrough in Nanodielectrics: PhD Student Revolution?

To promote scientific debate and ideas exchange in the field of electrical insulation and dielectrics, IEEE DEIS organized a Summer School in June 2015. The main purpose was to encour- age a discussion between a group of junior researchers and PhD students on three related hot topics in dielectrics research:

  • interfacial phenomena at nanoscale—taking the explanation of structure–property relations one step further;
  • increasing the heat transport in solid dielectrics by a factor of 10; and
  • how to obtain objective measures of the size of interfacial zones and the quality of dispersion and distribution in nano- composites.

These topics are still open issues among the scientific commu- nity.

The quiet medieval village of Bertinoro, famous for its an- cient hospitality traditions and not far from Bologna, was cho- sen to host the event. The amazing location and the excellent weather conditions were an ideal combination for undistracted discussions.

Following the original idea of S. Rowe and J. Fothergill, who organized the first workshop in Autrans in 2005, the summer school was organized in a novel way. The three-day program consisted of interactive brainstorm sessions with a limited num- ber of conventional lectures given by the organizers. This in- teractive approach was chosen to get the students much more involved in the development of novel ideas to achieve a break- through in the existing literature. Furthermore, the students could probably become future scientists of companies and uni- versities. Thus, it was very important to directly involve them in concrete problem solving. Moreover, exchanging ideas between people having different backgrounds was considered to be an added value to strengthen the summer school results. Finally, following the success of the summer school, there was a pos- sibility for students to arrange an international communication network, which was probably the main objective of the event. Indeed, the possibility to share ideas, information, experimen- tal work, and results within a scientific community working on similar topics could be extremely important for the professional growth of young researchers.

After a plenary introduction and a presentation of the three topics given by three IEEE DEIS experts, i.e., Peter Morshuis, Alun Vaughan, and Thomas Andritsch, the students were divid- ed into three groups. Each group was led by one of the senior mediators of high reputation in the field of nanodielectrics, to coordinate the discussions and keep them on the correct path. During the first day, each group tried to raise important issues and uncertainties in the field of nanodielectrics. The organiz- ers tried to initiate the discussions by providing a list of rele- vant questions. The latter were mostly related to the nature of nanometric fillers and their interaction with the host polymeric matrix. Moreover, more general topics, such as the existence of interfaces and interphases around nanoparticles, were discussed as well. Finally, some provocative contradictions and paradoxes

about the nanoscale were also suggested. In this way, students had the possibility to get to know each other better, to be in- volved more deeply in the topic, which could be novel for some of the participants, and to share their ideas. At the end of the day, during a plenary session, the groups summarized their interest- ing debates.

On the second day, each group, with the discreet presence of a moderator, summarized the important topics that were dis- cussed during the previous day in the form of propositions, i.e., hypotheses that can be confirmed or rejected by performing fur- ther experiments. The propositions were designed in order to better understand the uncertainties in the field of nanodielectrics and make the aim of the summer school more specific. All the contributions were then merged in a single list, taking into ac- count the proposals of each group. The three propositions are reported below:

  • Interactions occur over a range of dimensions and are de- termined by surface chemistry; the interactions determine performance.
  • Interphases are not the key determinant of electrical per- formance; direct observation of interphases is required to understand mechanisms.
  • If surface modification leads to improved electrical prop- erties, it also leads to improved thermal properties.

Moreover, every group planned its own design of experiments to further investigate some of the aforementioned propositions. In particular, group 3 focused on the first and third proposition, suggesting an international joint experiment including a round- robin test in order to

  • evaluate the role of nanoparticle surface through its chemi- cal modification. More specifically, the goal is to clarify the mechanism that influences the performance of nano- dielectrics when surface modified nanoparticles are used. The enhanced performance may be related to the enhanced interaction between nanoparticles and matrix, or to the sup- pression of the hydrophilicity of nanoparticles, or to both aforementioned mechanisms;
  • understand if thermal and electrical properties can be di- rectly correlated; and
    • investigate the role of water uptake on nanodielectric per- formance.

Polystyrene nanocomposites with untreated silica will be synthesized and compared with the same polymer filled with surface treated silica nanoparticles. First, the study will be fo- cused on the glass transition temperature, dielectric response, thermal conductivity, and water uptake dynamics of the pro- duced nanocomposites. The possibility to compare dielectric spectroscopy results obtained from the same samples by three different laboratories could be an interesting attempt to check scientific consistency of the tests. DC breakdown strength and temperature dependence of the dielectric response could be some of the further characterizations suitable to better study and understand material behavior. The idea is to summarize the ob- tained results in a journal paper and to arrange a joint presenta- tion for an international conference.

On the last day, a clear schedule of the planned experimen- tal campaign was designed on the basis of each expertise, and every member of group 3 was appointed to a specific role in the project. From the leading coordination, passing through sample realization, up to material characterizations, every role was clarified. At the end of the day, the outcome of the work of the three groups was summarized and preliminary conclusions were drawn. An unusual idea was then supposed: students could organize a special session in the upcoming International Confer- ence on Dielectrics, reflecting the outcome of their brainstorms. This opportunity can be also very useful to meet other people interested in the same topics and helpful to find other members to join this new research community.

Peter Morshuis Alun Vaughan Thomas Andritsch