2 Current status of the project

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2 1 Background The current research project started in September 2015 and its objective was to prepare and characterizise supramolecular block copolymer thin lms. Special interest was to study whether it would be possible to guide the structure physically along the electron beam lithographically prepared patterns and/or chemically by chemically modied surface properties. 2 Current status of the project So far the project has lasted 14 months (this was written in the beginning of November 2016) and I have prepared 64 dierent thin lm samples in 12 dierent sample series and characterized them with atomic force microscopy. I have also prepared patterns with electron beam lithography to act as substrates for selected samples. By now however, I have not had time to test chemical modication of the substrate for structure alignment. The scientically most promising samples base on block copolymer PMMA- b-p4vp (polymethyl methacrylate-block-poly(4-vinylpyridine)) complexed with phenolic resin. The pure block copolymer, having polymer block molecular masses of 30 kg/mol and 225 kg/mol for P4VP and PMMA respectively, self-assembles into spherical morphology within spin-coated thin lm as seen in the atomic force micrograph in Figure 1. 2

3 Figure 1: Atomic force micrograph recorded in tapping mode from PMMA- b-p4vp, where P4VP domains can be seen as spherical items. The periodicity of the structure can be estimated from the line prole to be around 23 nm. Blending the polymer with phenolic resin 37 wt-% leads to a morphological transition from spherical morphology to cylindrical morphology as can be seen in Figure 2. 3

4 Figure 2: Atomic force micrograph recorded in tapping mode from PMMA- b-p4vp complexed with 37 wt-% of phenolic resin. P4VP-phenolic resin domains can be seen as worm-like items. The periodicity of the structure can be estimated from the line prole to be around 53 nm. 4

5 The results show that phenolic resin is selective to P4VP polymer block. A morphological transition is only possible if the relative volume fractions of the dierent polymer domains are changed. This implies that the phenolic resin is located within the P4VP domain and increases its volume fraction, which then leads to the observed morphological transition. This result shows that the system behaves the same way as previously studied PS- b-p4vp complexed with phenolic resin. These results are already publishable i.e. should and will be published. Blending phenolic resing with PMMA-b-P4VP block copolymer yields to a very interesting material properties. The material has self-assembled structure in the level of tens of nanometers. The phenolic resin can be set with temperature to become highly crosslinked and hard material. For materials engineering point of view there are at least two possibilities for subsequent treatment: PMMA domains can be removed with high temperature treatment. Using subsequent electron beam lithography to write to the material and then remove the scissored PMMA chains by chemical treatment. I have already tested the rst scenario by keeping sample at 385 celsius degrees for one hour and AFM micrograph after temperature treatment can be seen in Figure 3. By comparing the line proles between Figures 2 and 3 one can observe, that the vallies between the objects have become deeper. This is a consequence of PMMA temperature degradation. 5

6 Figure 3: Atomic force micrograph recorded in tapping mode from PMMA- b-p4vp complexed with 37 wt-% of phenolic resin after temperature treatment. P4VP-phenolic resin domains can be seen as worm-like items. The periodicity of the structure can be estimated from the line prole to be around 58 nm. 6

7 The temperature threatment aects the whole sample. It would be very interesting to try to degrade PMMA locally using electron beam lithography techniques and to compare these two methods. 3 Future plans Although there are some results already, there are still much more research to be done. One of the most interesting topics is the chemical substrate modication. This would aect the most the samples with lamellar morphology. Without surface modication, it is very common that one of the polymer blocks has higher anity towards the silicon substrate, which leads to lamellar orientation parallel to substrate as depicted in Figure 4. With chemical modication, it would be possible to alter the anity and change to perpendicular orientation. Professor Salvadori has also invited me to collaborate in a project Core Facility de Conservação de Documentação Cientíca: papel e fotograa, where the purpose of the project is in-situ polymerization within a photography paper using supercritical carbon dioxide as a solvent. This is a very interesting project, for which I would nd my labor input useful due to my previous experience in the eld of polymers. Thus, I am willing to continue this fellowship and I am sure there is a possibility to get more publishable results. Therefore, I apply for ve months continuation for this project. Figure 4: Illustration of the possible eect of chemical substrate modication for lamellar morphology. 7