Contents lists available at ScienceDirect Reactive and Functional Polymers journal homepage: www.elsevier.com/locate/react Nanostructuration of polysilane-SiQDs composite by pulsed electrical discharges in water Liviu Sacarescu a,⁎ , Mihaela Simionescu a , Gabriela Sacarescu a , Antje Quade b , Juergen F. Kolb b , Camelia Miron b a Petru Poni Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, 700487 Iasi, Romania b Leibniz Institute for Plasma Science and Technology, Felix-Hausdorff-Str. 2, 17489, Greifswald, Germany ARTICLE INFO Keywords: Composites Nanoparticles Plasma Polysilane Quantum dots ABSTRACT Pulsed electrical discharges in water were used for nanostructuration of the polysilane-silicon quantum dots (SiQDs) composite dispersed in a cellulose acetate matrix. For this purpose, the polysilane-SiQDs composite was synthesized by chain scission of a poly[diphenyl-co-methyl(H)] oligomer in the presence of molten sodium and catalytic amounts of methyl(H) dichlorosilane. The resulting solid was utilized to prepare free standing thin films using the cellulose acetate matrix as support. Samples of these films were exposed to nanosecond pulsed elec- trical discharges in water. Through this approach, chemo-mechanical nanostructuration of specific silicon-based structures occurred by removing the excess of polysilane and by oxidative action. Fluorescence measurements of the plasma treated samples showed a higher intensity compared to the untreated ones. The elemental compo- sition and the morphology of the film surface were investigated by TEM, XPS, UHR-SEM and AFM analysis. Such a technique represents a new approach toward a selective processing of the polysilane-SiQDs composite to obtain patterns with different optoelectronic properties on various supports. 1. Introduction The research field of nanoparticles based materials is rapidly growing. Structures smaller than 100 nm present different properties compared to larger particles of the same material, and this aspect sti- mulated the studies in the field of semiconductor nanocrystals [1]. Such nanoparticles, known as quantum dots, exhibit excellent fluorescence properties when excited at specific wavelengths. These properties are useful in biosensing, medical imaging or even tumor treatment [2–7]. Since most of the conventional quantum dots are built using metallic elements, some issues concerning their biocompatibility and toxicity are still present [8–12]. In addition, their synthesis is complex and sometimes their stability is poor. Therefore, important research efforts have been dedicated toward new types of materials. One of them is silicon. This element is practically an inexhaustible resource of mate- rials for optoelectronics [13–16], and an important example is that of SiQDs. These nanostructures are biocompatible and suitable for bio- environmental applications without any risks [17,18]. SiQDs do not generate any heavy metal ions and their surface can be modified based on well-known chemistry approaches [19–21]. Their luminescence is also strongly dependent on their size [22]. However, research efforts are still required to clear fundamental aspects of their photophysics and to find reliable synthesis methods [23]. In addition, the physico-che- mical transformation of SiQDs under the action of specific irradiation fields and environments is practically unknown. New and interesting opportunities were opened when it was proved that SiQDs could be obtained using a polymeric precursor. Research showing a possible approach toward this goal has been published pre- viously [24–26]. It was demonstrated that polysilanes having highly reactive methylhydrosilyl units are capable to produce in situ silicon nanoparticles through the so-called chemo-restructuration processes. This happens during synthesis of polyhydrosilanes and finally leads to a nanocomposite material having silicon nanoparticles dispersed within the polymeric matrix. It was also shown that performing synthesis of the polymer in perfectly controlled conditions under microwave acti- vation, the content in SiQDs was close to 10% wt relative to polymer [27]. Polysilanes are sigma conjugated polymers with interesting op- tical and electronic properties that are far from being completely un- derstood. Therefore, interactions with electro-optical active groups present in the system could be of high interest from both fundamental and practical aspects. The polyhydrosilane SiQDs precursor is a linear copolymer where segments of diphenylsilyl units are statistically coupled with methyl- hydrosilyl units. Therefore, on one hand, such a structure has an http://dx.doi.org/10.1016/j.reactfunctpolym.2017.09.005 Received 14 June 2017; Received in revised form 7 September 2017; Accepted 14 September 2017 ⁎ Corresponding author. E-mail address: livius@icmpp.ro (L. Sacarescu). Reactive and Functional Polymers 120 (2017) 38–45 Available online 15 September 2017 1381-5148/ © 2017 Elsevier B.V. All rights reserved. MARK