Nano structural metal nano composites: synthesis, structural and thermal characterization

Orhan, Tuğba
Recently, the use of block copolymers in preparation of nanocomposites has received great attention as they form well-defined micelles. In this work, the synthesis of different metal functional copolymers, nano structural metal composites and investigation of their reaction mechanism and thermal characteristics by pyrolysis mass spectroscopy have been aimed. Namely, polyisoprene-block-poly2vinylpyridine, (PI-b-P2VP) and poly2vinylpyridine-block-polymetylmethacrylate, (PMMA-b-P2VP) were used as block copolymers and the thermal reaction of these copolymers with two different transition metal complexes Cr(CO)6 and HAuCl4.3H2O were investigated which mostly lead to the coordination of metal through nitrogen atom of the pyridine ring which then degrates to form nano particles. The samples were further characterized by TEM, ATR-FT-IR, UV-Vis and Direct-Pyrolysis Mass Spectroscopy techniques. TEM images proved the formation of nanoparticles and the results showed that synthesized Au nanoparticles have 2 to 3 fold larger size than Cr nanoparticles. ATR-FT-IR spectrum of metal functional copolymers showed that the disappearance of characteristic peaks of pyridine stretching and bending mode when metal coordinates to the pyridine nitrogen. Furthermore, the spectrum indicated the appearance of a new absorption peak at around 740 cm-1 which may be a clue for the coordination of gold(III) ion to the pyridine nitrogen. Different from chromium case, in the spectrum of Au3+-(PMMA-b-P2VP), CO stretching frequency of PMMA which may appear at around 1720–1718 cm-1 decreased in intensity while a new absorption peak appeared at around 1600 cm-1. This results reveals that electron deficient gold (III) ion prefers the coordination from both donor atoms namely carbonyl oxygen PMMA and pyridine nitrogen of P2VP in order to compensate its electron deficiency. In the UV-Vis spectrum of copolymers, Cr-functional copolymers showed a sharp absorption peak appeared at around 290 nm is attributed to a MLCT transition from chromium atom to * orbital of pyridine group. Furthermore, Au-functional copolymers showed a completely new absorption band at around 320 nm which can be associated again with a LMCT transition since gold is electron deficient and more willing to accept electrons from the ligand. Pyrolysis mass spectrometry analysis showed that poly2vinylpyridine blocks for each copolymers were affected similarly but polyisoprene block was not affected much from the coordination of metal compared to poly(methyl methacrylate) block in copolymers. For (PI-b-P2VP), Au3+ coordination to copolymer resulted in the higher thermal stability compared to Cr coordination. For (PMMA-b-P2VP), different from Cr, Au3+ coordination to P2VP nitrogen atom was extensive and PMMA based products changed drastically due to the coordination of electron deficient Au3+ to PMMA carbonyl group.


Nano structural metal composites : synthesis, structural and thermal characterization
Kaleli, Kadir; Kayran İşçi, Ceyhan; Department of Chemistry (2008)
In this work , metal functional polymers, namely Cr-PS-b-P2VP, Co-PS-b-P2VP, Au-PS-b-P2VP, Fe-PS-b-P2VP and Mo-PS-b-P2VP were prepared by thermal reaction of hexacarbonylchromium, Cr(CO)6, octacarbonyldicobalt,Co2(CO)8, hydrogentetrachloroaurate(III), H(AuCl4).4H2O, trichloroiron(III), FeCl3.6H2O, molybdenum(VI)oxide, MoO3 and PS-b-P2VP. TEM images indicated formation of AuIII, Cr and Co nanoparticles. On the other hand, crystalline structures were detected for Fe-PS-b-P2VP and Mo-PS-b-P2VP. Samples involvi...
Darzens reaction of substituted alfa-bromo acetophenones with acyl phosphonates
Pirkin, Eser; Demir, Ayhan Sıtkı; Department of Chemistry (2008)
Phosphorous containing small cycles are very important building blocks in organic and medicinal chemistry. Many of their derivatives, especially cyclopropyl- and 1,2- epoxypropylphosphonates, have attracted great attention due to the broad spectrum of their biological properties including antiviral, anticancer, antibiotic, antibacterial, pesticidal, insecticidal and enzyme inhibitory activities. The Darzens condensation is one of the most potential methodologies for the preperation of α,β-epoxy carbonyl com...
Conducting copolymers of random and block copolymers of electroactive and liquid crystalline monomers with pyrrole and thiophene
Camurlu, Pinar; Toppare, Levent Kamil; Yilmaz, Faruk; Yagci, Yusuf; Galli, Giancarlo (Informa UK Limited, 2007-03-01)
Block and random copolymers having 3-methyl thienylmethacrylate and 6-(4-cyanobiphenyl-4'-oxy) hexyl acrylate moieties were utilized as precursor polymers in this study. Electrochemical copolymerizations were performed in the presence of thiophene or pyrrole in acetonitrile-tetrabutylammonium tetrafluoroborate (TBAFB) at constant potential. The characterizations were performed by cyclic voltammetry (CV), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermal gravime...
Physical Characterization of Inclusion Complexes of Triphenyl Phosphate and Cyclodextrins in Solution.
Zhang, N; Zane, CP; Chen, Y; Yıldırım, Erol; Hinks, D; Tonelli, AE; Vinueza, NR; Pasquinelli, MA (American Chemical Society (ACS), 2020-01-16)
The goal of this work is to provide physical insights into the formation and stability of inclusion complexes (ICs) in aqueous solution between cyclodextrins (CDs) and a common flame retardant, triphenyl phosphate (TPP). Quantum chemistry calculations reveal the possible energetically favorable geometries of TPP in their 1:1 IC form with α-, β-, and γ-CDs as well as their associated complexation, conformational, and interaction energies. High-resolution mass spectrometry (MS) and tandem MS were used with el...
Design and synthesis of functional molecular squares
Akpınar, Handan; Akkaya, Engin Umut; Department of Chemistry (2006)
Self-assembly has big importance in synthesizing supramolecular structures. Highly fluorescent molecular squares with boradiazaindacene (BODIPY) building blocks were obtained via usage of metal driven self-asembly. The boradiazaindacene units were connected with the Pd(II) complex unit enforcing a near-90 degree angle between the building blocks. Thus, we believe we have the first example of BODIPY carrying fluorescent squares. With collective experience in BODIPY chemistry in our group, we may have the fir...
Citation Formats
T. Orhan, “Nano structural metal nano composites: synthesis, structural and thermal characterization,” M.S. - Master of Science, Middle East Technical University, 2009.