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This research involves the fabrication of encapsulated air-channels via acid-catalyzed degradation of photosensitive polycarbonates (PCs). There is a need for lower-temperature, degradable polymeric materials to fabricate buried air-channels for microelectromechanical systems (MEMS), microfluidic devices, and micro-reactors. Some polycarbonates undergo thermolytic degradation in the temperature range of 200 to 350 C. These polycarbonates are also known to undergo acid-catalyzed decomposition in the presence of catalytic amounts of acid. A small percentage of an acid in the polycarbonate formulation can greatly reduce the onset of decomposition temperature to the 100 to 180 C temperature range. The photoacid and thermalacid induced degradation behavior of PCs and its use as a sacrificial material for the formation of air-gaps have been studied in this work. The decomposition of several polycarbonates with the aid of in situ generated photo-acid has been demonstrated and applied to the fabrication of micro air-channels. Based on FT-IR, mass spectrometry, and thermogravimetric analysis (TGA), a degradation mechanism was proposed.[849]

With increasing evidence for the existence of complexes of intact alkanes with transition metals ("σ complexes") as intermediates in many oxidative-addition/reductive-elimination reactions of alkanes (equation 1), there is considerable interest in learning about their structure, bonding, energetics, and dynamical properties. [1][2][3][4][5] Previously, we reported 3d indirect evidence for the methane complex [Cn*Rh(CH 4 )(PMe 3 )] + . 6 We now present indirect evidence that σ complexes of higher alkanes with rhodium in the triamine environment also form as transient intermediates, and that the metal moves along the chain with a barrier that is slightly below the barrier to alkane dissociation.Alkyl hydride complexes [CnRh(H)(R)(L)]X {Cn ) 1,4,7triazacyclononane; 6 R ) Me, Et, Bu, hexyl, and decyl; L ) P(OMe) 3 ; X -) -OTf (triflate, CF 3 SO 3 -) or -BAr 4 ( -B[3,5-(CF 3 ) 2 C 6 H 3 )] 4 )} have been prepared in 21-32% overall yields from RhCl 3 (H 2 O) n by methods completely analogous to those reported for [CnRh(H)(R)(PMe 3 )]X (R ) Me, Et) 7 and fully characterized. In benzene from 40 to 80 °C, the [CnRh(H)(R)-(L)](BAr 4 ) all react with clean first-order kinetics and quantitative formation of [CnRh(H)(C 6 H 5 )(L)](BAr 4 ), which has also been characterized. Arrhenius plots of the benzene reaction give ∆H q ranging from 29.7 to 33.1 kcal/mol and ∆S q from 9.6 to 18.4 eu. Reaction rates of the Et, Bu, hexyl, and decyl derivatives are very similar, while the methyl compound is about 10-fold slower. The size of ∆S q is consistent with a dissociative mechanism for replacement of alkane by benzene, and there is no dependence of the rate of loss of hexane from [CnRh(H)(hexyl)(L)](BAr 4 ) on benzene concentration in C 6 F 6 solution. 8

From the reactions between diarylzinc compounds (Ar2Zn) and the alcohol (Pr(i)2CHOH) in toluene, the compounds [ArZn(OCHPr(i)2)]2 (Ar = C6H5, C6F5, p-CF3C6H4, and 2,4,6-Me3C6H2) have been isolated and shown to exist in equilibra with the trinuclear complexes Ar2Zn3(OCHPr(i)2)4 and Ar2Zn when Ar = C6H5, C6F5, and p-CF3C6H4. The trinuclear complexes have also been prepared from reactions of the Ar2Zn compounds with the alcohol, which reveals that the ease of Zn-C(aryl) bond cleavage is sensitive to the nature of the Ar group: C6H5 > 4-CF3C6H4 > C6F5. The molecular structures of Ar2Zn3(OCHPr(i)2)4 where Ar = p-CF3C6H4 and C6F5 and [ArZn(OCHPr(i)2)]2 where Ar = C6F5, p-CF3C6H4, and 2,4,6-Me3C6H2 are reported based on single-crystal X-ray diffraction studies. The X-ray structure of Zn(p-CF3C6H4)2 is also reported. The reactivity of these new compounds toward the polymerization of propylene oxide (PO) and the copolymerization of PO and CO2 have been investigated along with related reactions involving the partial hydrolysis of the Ar2Zn and R2Zn compounds, where R = t-Bu, n-Bu, and n-Oct. These results are compared with the previous studies employing Et2Zn as an organozinc precursor.

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