Polymeric Deterministic Doping

An accurate control of the dose and the position of dopant atoms in semiconductive materials is strictly required in the production of transistors with dimensions of few nanometers and is then strongly requested by microelectronics industry. In this thesis a doping technology based on functionalized polymers is proposed. Several dopant polymers were synthesized by ATRP, NMP and Solid-Phase synthesis and tested as dopant system. Because the control of the amount of dopant atoms is performed by a "grafting to" approach, the mechanism of this reaction was investigated deep inside. A new mechanochemical model for the "grafting to" reaction was proposed in contrast with the classical one, based on diffusion

Following the fate of microplastic in four abiotic and biotic matrices along the Ticino River (North Italy)

: Microplastics (MPs) are emerging contaminants in freshwater systems that have already attracted much scientific interest, but little attention has been paid to a multi-matrix analysis of MP occurrences along the length of a river. The present research provides the first record of MP contamination of four abiotic and biotic matrices from a river ecosystem simultaneously analysed. MPs were isolated and identified by micro-Fourier Transform Infrared (μ-FTIR) spectroscopy from samples collected along the Ticino River in North Italy during spring 2019. Abiotic samples were surface water (n = 18, 33 MPs m-3) and sediment (n = 18, 11 MPs kg-1), while biological samples consisted of stomach and gut content of fish (n = 18, wels catfish, Silurus glanis, 0.032 MPs g-1) and macroinvertebrates (n = 90, caddisfly larvae, Hydropsychidae, 0.03 MPs mg-1). MPs were found in biota from all stations; 44% of fish and 61% of macroinvertebrate samples contained MPs. The calculated unit-consistent concentration ratios indicate that both S. glanis and Hydropsychidae larvae had a consistent higher amount of MPs than their respective medium (sediment and water), strongly suggesting an efficient uptake pathway into organisms. MP levels in surface water, sediment, fish and macroinvertebrates were not correlated and did not increase with the river's length. From our mass balance calculations, the Ticino River transports a consistent amount of MP (yearly load of 3.40 × 1011 ± 1.1 × 1011 MPs) to the Po River. This MP load was almost half than an estimated MP load from wastewater treatment plants (WWTPs). On that basis and supported by the finding that MP concentration in sediment was mostly opposed to that in surface water but was on average 750-fold higher compared to the water matrix, we surmise that the complex hydrological network of the Ticino River retains a consistent amount of MPs which might build up over time

Bioinspired polypeptoids for the deterministic doping of semiconductors

Polymers are widely used in the field of electronics. To move in the way of nanoelectronics, polymers can be employed for the scaling down of transistors by modulating the doping of semiconductors. Many methodologies have been explored to precisely introduce impurities inside a semiconductor. Among them “monolayer doping holds a special position. In this methodology, the density of doping atoms is controlled by the steric hindrance of the carrier molecules containing the dopant atom. Even if polymers such as polystyrene and poly-(methyl methacrylate) with a terminal phosphate moiety and narrow dispersity, have been used to dope silicon substrates, the control of polydispersity is still a challenge. Bioinspired polypeptoids are promising for this application. Polypeptoids are synthesized by solid-phase sub-monomer synthesis. It allows for control of the unit sequence and therefore the molecular weight due to their unit-by-unit assembly mechanism, leading to monodisperse systems