All reagents for the synthesis of the PILs were purchased and used without additional purification. The list of reagents is the following: 4-methylpyridine 98%, methylimidazole 99% and tetramethylguanidine 99% from Alfa Aesar (Tewksbury, MA, USA); pyridine p.a. and sulfuric acid 95–97% from Merk (Rahway, NJ, USA); 1,8-diazabicyclo(5.4.0)undec-7-ene 98% and methanesulfonic acid 99% from Sigma-Aldrich (Rahway, NJ, USA).
The solvents were acetonitrile 99.8% from Merck (Darmstadt, Germany) and deuterated water 99.9% from Eurisotop (Gif sur Yvette, France). Polyethylene glycol (MW 200)—PEG200 was from Sigma-Aldrich (Rahway, NJ, USA), with water content < 0.5%. Distilled and deionized water (DD) was obtained with a Millipore system.
Si b100N wafers (Si-Mat, Kaufering, Germany), with 0.5 mm of thickness, 1 nm of root mean square (RMS) roughness and 1121–1428 HV of hardness, were cut in squares (1 × 1 cm2) to be used in the tribological tests and the contact angle measurements. Spheres of stainless steel (SS) AISI 316L grade 100 (Atlas Ball and Bearing Co. Ltd., Walsall, UK) with 6 mm of diameter, roughness RMS = 1 µm and hardness of 260–390 HV and Si spheres (J. Hauser GMBH and Co., Solms, Germany) with 6 mm of diameter, 15 nm of RMS roughness and 1412 HV of hardness were used as counter bodies.
The solvents were acetonitrile 99.8% from Merck (Darmstadt, Germany) and deuterated water 99.9% from Eurisotop (Gif sur Yvette, France). Polyethylene glycol (MW 200)—PEG200 was from Sigma-Aldrich (Rahway, NJ, USA), with water content < 0.5%. Distilled and deionized water (DD) was obtained with a Millipore system.
Si b100N wafers (Si-Mat, Kaufering, Germany), with 0.5 mm of thickness, 1 nm of root mean square (RMS) roughness and 1121–1428 HV of hardness, were cut in squares (1 × 1 cm2) to be used in the tribological tests and the contact angle measurements. Spheres of stainless steel (SS) AISI 316L grade 100 (Atlas Ball and Bearing Co. Ltd., Walsall, UK) with 6 mm of diameter, roughness RMS = 1 µm and hardness of 260–390 HV and Si spheres (J. Hauser GMBH and Co., Solms, Germany) with 6 mm of diameter, 15 nm of RMS roughness and 1412 HV of hardness were used as counter bodies.