Structural and optical properties of nematic liquid crystalline PPI dendrimers encapsulated with Co nanoparticles

Darbe tirtos struktūrinės ir spektroskopinės dviejų šeimų nematinių skystakristalinių dendrimerų ištirpintų chloroforme savybės. Taip pat struktūrinės, spektroskopinės ir magnetooptinės dendrimerų su įterptomis Co nanodalelėmis savybės. Dviejų šeimų skystakristalinių dendrimerų ištirpintų chloroforme optiniai tyrimai parodė, kad pirmos šeimos skystakristalinių dendrimerų vidinę dalį nusakanti sugerties juosta antros ir penktos generacijų atžvilgiu yra paslinkusi per 8nm, tuo tarpu antros šeimos atitinkamai pirmos ir penktos generacijų atžvilgiu per 19nm. Dendrimerų su įterptomis Co nanodalelėmis magnetooptiniai tyrimai parodė, kad Co nanodalelės gali būti valdomos magnetiniais laukais.Dendritic structure is one of the prevalent topologies on our planet [1]. Dendrimers is generally described as monodispersed low viscosity macromolecules with highly branched, well defined 3D structure, first reported in 1978 by Vögtle. They are always composed of a core molecule and dendritic branches extended from core to terminal groups [26]. The number of functional groups on the dendrimer surface increases exponentially as a function of generation, of that in the higher generations they become much more spherical and amplified highly ordered architectures. Liquid crystalline dendrimers of their unique structural and physical properties have attached considerable attention. Because of their hyper branched spherical structure, interior inside dendrimers have fixed cavities. Strong interaction forces in the terminal mesogenic units determine that in the interior can be incorporated atoms, ions, guest molecules or nanoparticles. They are particularly well suited materials for hosting nanoparticles of the following reasons: nanoparticles are stabilized and don’t agglomerate, dendrimer branches can be use as selective gates to control access of small molecules [19]. As result of their architecture, dendrimers can possess essential physical, chemical and biological properties and whole range of applications in energy, medicine, engineering, information technology and ect. We present optical and structural studies of liquid crystalline poly(propylene imine) (PPI) dendrimers with different generations (generations 1-5) prepared in chloroform and magneto optical studies of PPI dendrimer (generation 5) with incorporated Co nanoparticles diameter 1nm. UV-VIS spectra in chloroform solution displaying that enlargement of the chain number leads to the 8nm and 19nm shift spectra of mesogenic groups to the IR wavelength region for both two PPI dendrimer families. These optical studies of PPI dendrimer demonstrate flexible structure and better possibility to capture the external nanoparticle. Although magnetic properties of Co nanoparticles strongly depend on size, it is shown that dendrimer encapsulated 1nm Co nanoparticles are sense to magnetic fields. It is known that these nanosized particles show superparamagnetic properties and cobalt become very important for their applications in magnetic storage and recording technology.Švietimo akademijaVytauto Didžiojo universiteta