Inclusion Polymerization and Doping in Zeolite Channels. Polyaniline

Aniline has been polymerized in the three-dimensional channel system of zeolite Y. The monomer was diffused into zeolites with different levels of acidity from hexane solution. Subsequent admission of peroxydisulfate or iodate from aqueous solution yielded the intrazeolite polymers, as demonstrated by FT-IR, electronic absorption data and recovery of the included polymer. With S2O82-, the intrazeolite products are a function of the proton content of the zeolite. Polymer is only formed when a sufficient supply of protons is present in the zeolite host. When neutral iodate solution is used, no polymer is formed in NaY and acid zeolites, but at low pH aniline polymerizes in all zeolites. The open pore system of the zeolite host can be accessed by base such that the intrazeolite protonated polymer is transformed into the corresponding neutral polymer. The polymer chains encapsulated in zeolite hosts represent a new class of low- dimensional electronic materials

Molecular recognition on acoustic wave devices

Microporous thin films composed either of zeolite crystals embedded in sol-gel derived glass or of a molecular coupling layer, zeolite crystals and a porous silica overlayer, were formed on the gold electrodes of Quartz Crystal Microbalances (QCM). The microporosity of the thin films was characterized by in situ nitrogen and vapor sorption isotherms. Both preparation methods result in thin films with substantial microporosity. Selective adsorption based on molecular size exclusion from the microporous films could be achieved

EXAFS study of nickel exchanged into zeolite Y

EXAFS and near edge spectroscopy were used to monitor changes i n Ni coordination as a function of treatment conditions after aqueous exchange into zeolite Y. Our results suggest that after calcination and dehydration under the conditions of this study, major site occupancy for Ni appears to be in the tri-coordinate exchange sites , and not i n the hexagonal prisms as suggested by previous x-ray diffraction results

EXAFS study of nickel tetracarbonyl and nickel clusters in zeolite Y

Adsorption and thermal decomposition of Ni(CO)4 in the cage system of zeolite Y have been studied with EXAFS, electron microscopy and IR spectroscopy , Ni(CO)4 is adsorbed as an intact molecule in both cation - free zeolite Y and NaY. Symmetry changes of the molecule in NaY are assigned to the formation of Na—OC-IMi bridges. Thermal treatment of the Ni(CO)4/NaY adduct leads to loss of CO concomitant with the formation of a binodal Ni phase. A major part of the forms clusters with diameter between 0.5 and about 1.5 nm, in addition to larger crystallites (5-30 nm), sticking at the outer surface of the zeolite matrix., The Ni-Ni scattering amplitude indicates increasing average particle size with increasing temperature

EXAFS Analysis of Size-Constrained Semiconducting Materials

Semiconducting materials such as CdSe, CdS, PbS and GaP are included in crystalline zeolite Y and mordenite and structurally flexible ethylene-methacrylic acid copolymer solid matrices. EXAFS analysis reveals formation of species with dimensions of molecular size up to ca. 13 A in the crystalline hosts, while the polymer matrices allow agglomeration of larger semiconducting particles. Zeolite anchored structures are distinctively different to small particles with bulk crystal structure as usually found in colloidal systems