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A series of reactive phenylethynyl endcapped imide oligomers has been prepared in either fully cyclized or amic acid precursor form. Soluble oligomers have been synthesized with controlled molecular weights ranging from 2- to 12 Kg/mol. Molecular weight characterization was performed using SEC (size exclusion chromatography) and 13C-NMR, revealing good agreement between the theoretical and experimental (Mn) values. Crosslinked polyimides were obtained by solution or melt processing the oligomers into films and gradually heating in a programmed temperature manner up to the appropriate reaction temperature for the phenylethynyl groups, which is approximately 350-400°C. Thermal analysis of the resulting films showed high glass transition temperatures (>300°C) and excellent thermal stability, comparable to those found for thermoplastic control polyimides. The crosslinked films also had exceptional solvent resistance as evidenced by a high gel fraction (greater than or equal to 95%) following extraction in common solvents for several days. This was in contrast to the amorphous thermoplastic controls, which quickly dissolved upon immersion in solvents. The monomers used for synthesizing the polyimide oligomers were varied systematically within the series to study the influence of both molecular structure and molecular weight on the physical and film-forming properties. The incorporation of fluorinated monomers, such as 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), reduced water absorption and lowered the dielectric constant relative to non-fluorinated polyimides in the series. When flexible ether linkages were incorporated in the repeat unit by using 4,4'-oxydianiline (ODA), relatively more ductile solvent-cast films were obtained from oligomers having Mn values as low as 10 Kg/mol. Additionally, oligomer Mn and the relative rigidity/symmetry of the repeat unit structure greatly influenced the solubility of polyimides in NMP. For example, even 6FDA/p-phenylenediamine based oligomers with Mn values targeted below 10 Kg/mol precipitated from NMP at 180°C during solution imidization. The relationship between solution viscosities of polyimide and poly(amic acid) thermosetting oligomers and wetting/spreading ability to form continuous films during spin casting was elucidated. Employing o-dimethoxybenzene (DMB) as a cosolvent with NMP improved the film-forming ability of the fully imidized 6FDA/ODA oligomer series. This was evidenced by a decrease in viscosity (via suppression of physical-type gel formation) and better overall coverage and clarity of the films. Humidity was found to have a detrimental effect, causing the polyimide oligomers to phase separate to form cloudy or porous films. When moisture was reduced, oligomers having Mn greater than or equal to 6 Kg/mol formed spin cast films of <20 micrometer thickness with good qualitative adhesion to several inorganic substrates. Dielectric constants (epsilon) were estimated for several of the polyimides by measuring the refractive indices (n) of the films and using Maxwell's relationship (epsilon at optical frequencies is equal to n raised to the second power). The apparent dielectric constants were low, ranging from 2.47 to 2.75. The novel combination of low dielectric constant, solvent resistance and isotropic physical properties inherent in the thermosetting polyimide oligomers makes these materials excellent candidates for use as thin film insulating layers in microelectronics packaging applications. / Ph. D.

Orientador: Isabel Cristina Sales Fontes Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T10:34:05Z (GMT). No. of bitstreams: 1 Ferreira_ClaudiodeCastro_M.pdf: 1652977 bytes, checksum: b266745fcbc738cc97c41fdc4d79a00b (MD5) Previous issue date: 2014 / Resumo: / Resumo: Neste trabalho, prepararam-se fases estacionárias (FE) fluoradas capeadas para utilização em Cromatografia Líquida de Alta Eficiência em Fase Reversa (CLAE-FR). A preparação da FE consistiu na sorção do polímero poli(metil-3,3,3-trifluorproprilsiloxano) (PMTFS) sobre sílica, tipo B, com tamanho de partícula de 5 ?m, seguido de imobilização térmica a 226 oC, por 12 horas e extração com diclorometano, a fim de eliminar o polímero não aderido ao suporte. A FE imobilizada, Si(PMTFS), foi submetida à reação de capeamento com trimetilclorossilano e hexametildissilaxano, para a redução dos grupos silanóis que não foram recobertos pelo polímero. Testes físico-químicos e cromatográficos comprovaram a eficiência da imobilização do polímero e do capeamento. O desempenho cromatográfico da FE fluorada capeada, Si(PMTFS)ec, foi superior ao da não capeada e os testes de Tanaka e colaboradores demonstraram que o capeamento diminuiu a atividade silanofílica da FE e aumentou a sua hidrofobicidade. A FE Si(PMTFS)ec apresentou o mecanismo "U-shape", pois se observou o aumento da retenção de compostos básicos e polares em altas porcentagens do modificador orgânico na fase móvel. As FE de Si(PMTFS)ec apresentaram estabilidade química superior às FE não capeadas, porém, elas mostraram-se mais instáveis que as FE C8, C18 preparadas no grupo. Embora a estabilidade química à fase móvel em meio básica seja uma desvantagem, a mesma possui o mecanismo "U-shape" que pode ser utilizado para aumentar a retenção dos compostos básicos, sem o uso de condições drásticas de pH, além de ser uma FE mais apropriada quando se emprega o espectrômetro de massas, pois a alta concentração de solvente orgânico na fase móvel melhora a ionização dos analitos, aumentando as suas detectabilidades. A FE Si(PMTFS)ec constitui em uma alternativa bem sucedida para emprego em CLAE-FR, devido a sua capacidade em separar vários tipos de compostos / Abstract: / Abstract: In this work, end-capped fluorinated stationary phases (SP) for use in High-Performance Liquid Chromatography on Reversed Phase (RP-HPLC) were prepared. The preparation of the SP consisted in the sorption of the polymer poly(methyl-3,3,3-trifluorproprilsiloxane) (PMTFS) onto type B silica, with particle size of 5 µm, followed by thermal immobilization at 226 °C for 12 h and extraction with dichloromethane to eliminate the polymer that had not interacted with the support. The immobilized SP, Si (PMTFS), was subjected to an end-capping reaction to reduce the silanol groups that were not covered by the polymer. Physical-chemical and chromatographic tests were conducted to evaluate the efficiency of the immobilization of the polymer and of the end-capping reaction. The chromatographic performance of the end-capped fluorinated SP, Si (PMTFS)ec, was greater than that of the non-end-capped phase. The Tanaka tests showed a decrease in silanophilic activity and an increase in hydrophobicity. The Si (PMTFS)ec SP showed a U-shaped mechanism, because of the observed increase in retention of basic compounds at high percentages of the organic component in the mobile phase. The Si (PMTFS)ec SP showed superior chemical stability to non-end-capped SP, however, less stability than C8 and C-18 SP also prepared by the group. Although chemical stability in alkaline mobile phase is a disadvantage, it has a "U-shape" mechanism that can be used to increase the retention of basic compounds without the use of drastic conditions of pH, and is more appropriate for use with a mass spectrometer. Due to the high concentrations of organic solvent in the mobile phase the ionization of the analytes is better, increasing the detectability. The Si (PMTFS)ec SP can be used in RP-HPLC due to its ability to separate various types of compounds / Mestrado / Quimica Analitica / Mestre em Química