Gabriela Sacarescu

Si-H functional polysilanes via a homogeneous reductive coupling reaction

A polysilane copolymer with reactive Si-H side groups was obtained through a homogeeous coupling reaction of dichlorodiphenylsilane with dichloromethylsilane. The reaction was carried out in a tetrahydrofuran (THF) solution of a sodium-potasium alloy complex with 18-crown-6 with a well defined composition of alkali metal ion pairs (Mt + /crown ether, Mt ― ) at -75°C. The product was characterized using 1 H NMR, 13 C NMR, FT-IR and UV/Visible spectroscopies and gel permeation chromatography. The result were compared with those obtained by the heterogeneous coupling reaction of the same monomers.

Synthesis of polysilane–bis(salicyliden)ethylenediamine Ni(II) complex

Abstract This paper describes the synthesis of a new coordination polymer prepared through the polycondensation reaction of α,ω-bis(chloromethyl)-polymethylphenylsilane with the Ni(II) complex of bis(salicylidene)ethylenediamine (salen). For this purpose, a new preparation method of the chloromethylated polysilane was presented along with the synthesis and characterisation of the polymer–metal complex. IR, 1 H-NMR and UV–Vis spectral analyses as well as GPC and TGA were used to investigate the new chemical structures.

Polyhydrosilanes I. Synthesis

Abstract Using the well known Wurtz coupling technique, polyhydrosilanes copolymers with diphenyl - and methyl(phenyl) - sequences, were synthesised. This work describes the possibility to maintain stable Si-H group and to obtain in good yields, soluble, high molecular, functional polysilanes. IR, 1-NMR, 13C, UV spectral data, quantitative elemental Si and H (from Si-H) analyses and indirect molecular weight investigation sustain the molecular structure of the copolysilanes.

Photosensitive crown ether-siloxane copolymers bearing azobenzene chromophores

This paper presents the synthesis procedure of new photosensitive siloxane–crown ether copolymers using the polycondensation reaction of an oligosiloxane with COCl end groups and bisazo derivatives of dibenzo-18-crown-6 polyether. The azodiphenol compounds were prepared via the coupling reaction of 4,4 0 -diamine-DB18C6 diazonium salt with phenol or 1-naphthol. The polymers were characterized by IR absorption and 1 H-NMR spectra as well as by thermal analysis and GPC. A study of the photoisomerization process as well as the thermal relaxation of azoaromatic chromophores in the polysiloxane–crown ether copolymer in dimethyl sulfoxide solution and of the corresponding complexes with KSCN was also presented. 2002 Elsevier Science Ltd. All rights reserved.

Polysilane—Metal Complexes for Organic Semiconductors

New polysilane-metal complexes structures were obtained by the polycondensation reaction of α,ω-bis(chloromethyl)-polymethylphenylsilane with the Ni (II) complex of bis(salicylidene)ethylenedia-mine (salen). The chloro-functionalized polysilane was obtained by a modified Wurtz coupling procedure at low temperatures. To obtain the polymer-metal complex the resulted macroligand was complexed with metal cations. This structure is characterized by a highly localized electroactivitry in the redox moiety combined with a specific σ conjugative effect in the polysilane chain. Infrared, 1H NMR and UV-vis spectral analysis as well as gel permeation chromatography and thermogravimetric analysis were used to investigate the new chemical structures.

Microwave-Assisted Synthesis of Functional Polysilanes

The presence of reactive Si–H groups in polyhydrosilanes allows to obtain different polysilane structures with various functionalities through catalytic addition of unsaturated organic compounds. An efficient synthesis method of such functional polysilanes has been achieved using a conventional method as well as microwave irradiation. The effect of microwave irradiation on chemical reactions is generally evaluated by comparing the time needed to obtain a desired yield of final products with respect to conventional thermal heating. Research in the area of chemical synthesis has shown some potential advantages in the ability not only to drive chemical reactions but to perform them in reduced time-scale. Comparison of microwaveassisted synthesis of functional polysilanes with the conventional synthetic method demonstrates advantages related to shorter reaction times, better reaction yields and milder reaction conditions, a fact that allows a better protection of polysilane chemical structure.

Microwave-assisted Wurtz coupling of methylphenyldichlorosilane in solvent-free conditions

Abstract This communication describes the synthesis of polymethylphenylsilane by the microwave-assisted coupling of methylphenyldichlorosilane using metallic sodium in solvent free conditions. The instant heating melts the sodium particles within the liquid methylphenyldichlorosilane and the polymerization reaction is achieved in minutes with total consumption of the monomer. The process is carried out in a high performance microwave reactor using the closed vessel operating facility which ensures control of the reaction parameters and highly reproducible results.

Synthesis and Characterization of Polysilane-Organometallic Complexes

A new polysilane with pendant metal complex segments was synthesized and characterized. For this purpose a macroligand has been prepared starting from a iodopropyl-functionalized polysilane and a bis(salicylideneimine) derivative. Under mild reaction temperature this polymeric ligand was able to form crosslinked structures. The material was then doped with metal cations and was investigated to observe the system behavior near the gelation point. The UV-vis spectrum of the new material indicated that the electronic structures of the conjugate polysilane chain and metal complex remained unaffected by the condensation reaction process. Similar polymeric structures could be useful to build new organic electroconductive devices.

Polydiphenylsilanes bearing photosensitive azocrown groups

This work presents the synthesis and particularities of the reversible trans-cis UV light induced photoisomerization process of a polydiphenylsilane bearing (propyl-oxyphenylazo)dibenzo-18-crown-6 side groups.

Synthesis of Polysiloxaneimide with Piezoelectric Response

A new segmented polysiloxaneimide was synthesized by solution polycondensation of N, N bis(hydroxyethyl)benzophenontetracarboxylic diimide with siloxane diacid chloride. The copolymer was obtained with good yield and high molecular weight. The characterization by IR and 1H-NMR spectrometry and a study of the properties such as solubility and thermal behaviour of this copolymer are presented. A corona poling study was performed to obtain information about the piezoelectric behaviour of polysiloxaneimide. The remanent dielectric constants of the polarized samples were compared with those of well-known piezoelectric polymers.