New thermal crosslinkers based on triazene: crosslinking of fluorinated polyimides and aromatic polymers

Lau, Aldrich N. K.; Vo, Lanchi

doi:10.1021/ma00052a034

Cited by 14 publications

(8 citation statements)

References 2 publications

(3 reference statements)

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“…The decreased intensity of the SIMS spectra also indicated a polymer network. In addition, it was demonstrated that the structurally related monomeric bis-triazene compounds can be used as thermal cross-linkers for polyimides and aromatic polymers [156]. Therefore only cross-linking is shown in Scheme 6.…”

Section: Discussionmentioning

confidence: 99%

“…This additional energy can lead to a higher decomposition rate than expected from the laser energy alone. Thermogravimetric analysis (TG) of the polymer showed that the exothermic decomposition starts at about 500 K [121,156]. In the case of the photochemical decomposition, no experimental data, whether of an exo-or endothermic process, are available.…”

Section: Reprinted With Permission Of [Ref 60] Copy-right (1996) Spmentioning

confidence: 99%

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Laser Application of Polymers

Lippert

2004

Polymers and Light

148

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Laser ablation of polymers has been studied with designed materials to evaluate the mechanism of ablation and the role of photochemically active groups on the ablation process, and to test possible applications of laser ablation and designed polymers. The incorporation of photochemically active groups lowers the threshold of ablation and allows high-quality structuring without contamination and modification of the remaining surface. The decomposition of the active chromophore takes place during the excitation pulse of the laser and gaseous products are ejected with supersonic velocity. Time-of-flight mass spectrometry reveals that a metastable species is among the products, suggesting that excited electronic states are involved in the ablation process. Experiments with a reference material, i.e., polyimide, for which a photothermal ablation mechanism has been suggested, exhibited pronounced differences. These results strongly suggest that, in case of designed polymers which contain photochemically active groups, a photochemical part in the ablation mechanism cannot be neglected. Various potential applications for laser ablation and the special photopolymers were evaluated and it became clear that the potential of laser ablation and specially designed material is in the field of microstructuring. Laser ablation can be used to fabricate three-dimensional elements, e.g., microoptical elements.Keywords Laser ablation · Ablation mechanism · Photopolymers · Polyimide · Spectroscopy This was not always true, of course. For many years, the laser was viewed as "an answer in search of a question". That is, it was seen as an elegant device, but one with no real useful application outside of fundamental scientific research. In the last two to three decades however, numerous laser applications have moved from the laboratory to the industrial workplace or the commercial market. Lasers are unique energy sources characterized by their spectral purity, spatial and temporal coherence, and high average peak intensity. Each of these characteristics has led to applications that take advantage of these qualities: -Spatial coherence: e.g., remote sensing, range finding and many holographic techniques. -Spectral purity: e.g., atmospheric monitoring based on high-resolution spectroscopies. -and of course the many other applications in communication and storage, e.g., CDs.All of these high-tech applications have come to define everyday life in the late twentieth century. One property of lasers, however, that of high intensity, did not immediately lead to "delicate" applications but rather to those requiring "brute force". That is, the laser was used in applications for removing material or heating. The first realistic applications involved cutting, drilling, and welding, and the laser was little more advanced than a saw, a drill, or a torch. In a humorous vein A.L. Schawlow proposed and demonstrated the first "laser eraser" in 1965 [4], using the different absorptivities of paper and ink to remove the ink without damaging the und...

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Section: Discussionmentioning

confidence: 99%

Section: Reprinted With Permission Of [Ref 60] Copy-right (1996) Spmentioning

confidence: 99%

Laser Application of Polymers

Lippert

2004

Polymers and Light

148

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“…Later, Marek et al 45 changed the dianhydride system to 4,49-(hexafluoroisopropylidene) bis(phthalic anhydride) (6FDA) since polyimides prepared from monomers containing hexafluoroisopropylidene groups are attractive materials because of their high transparency, low dielectric constant, low moisture absorption, resistance to photochemical degradation, good solubility and gas permeation properties. [46][47][48][49][50] Moreover, 6FDA was less reactive in the acylation of amines than pyromellitic dianhydride (PMDA) and gave polyimides with lower molecular weights, 51 with the latter being strongly dependent on the diamine monomer that is used. All the resulting polyimides with 6FDA as a dianhydride unit were soluble in tetrahydrofuran and polar aprotic solvents except the polyimide with DA = 10, (6FDA/DA-10) whereas dimethyl sulfoxide at room temperature was not a good solvent for these polymers.…”

Section: Flexible Methylene (-Ch 2 -) Chainmentioning

confidence: 99%

Solubility improvements in aromatic polyimides by macromolecular engineering

et al. 2012

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Polyimides are proved to be an important class of polymers due to their outstanding set of physical and chemical properties. However, this class of polymers suffers from poor processability, which limits their scope of application. This review article deals with approaches that have been undertaken by different researchers to improve the processability of this class of polymers. Mostly, these are synthetic approaches using new diamine and dianhydride monomers that reduce the interchain interaction of the final poyimide by flexibilizing the polymer chain or increasing the fraction free volume. Accordingly, the structural factors that are responsible for better processability are discussed and representative diamine and diahydride structures are tabulated under different categories. Major efforts towards development of soluble polyimides but maintaining excellent mechanical and thermal properties have been done by our group and are also covered in this article.

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“…The decreased intensity of the SIMS spectra also indicated a polymer network. In addition it was demonstrated that the structurally related monomeric bis(triazeno) compounds can be used as thermal cross-linkers for polyimides and aromatic polymers .…”

Section: Discussionmentioning

confidence: 99%

Irradiation Wavelength Selective Surface Modification of a Triazeno Polymer

et al. 1996

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Standard spectroscopic and surface analysis techniques were used to study a triazeno polymer after laser treatment. Two different excimer lasers, KrF at 248 nm and XeCl at 308 nm, were applied as irradiation sources. For both excimer lasers fluences below and above the threshold of ablation were used. In the case of fluences below the threshold of ablation the irradiation led to a decrease of the absorption of the triazeno chromophore. From XPS spectrum and contact angle measurements a surface oxidation of the polymer is identified. After irradiation with fluences above the threshold of ablation for both irradiation wavelengths a different behavior is observed. Irradiation with the XeCl laser led to a less pronounced surface roughening as compared to KrF laser treatment. With the XPS and contact angle measurements, only slight changes could be detected. A totally different behavior was found for irradiation with the KrF excimer laser. The surface of the polymer turned black after the irradiation, and the oxygen and nitrogen content is drastically reduced, as determined from the XPS spectrum. The SEM pictures revealed the appearance of microstructures of about 5 µm size with some "treelike" structures at the top of the "naps". Contact angle measurements show also the existence of a nonpolar surface. Spectroscopic techniques showed that there exists a clear difference between the irradiation of the triazeno polymer at the two wavelengths under ablation conditions. Excitation of the triazeno chromophore at 308 nm leads to clear ablation, whereas the irradiation with 248 nm introduces microstructures and a carbonized surface.

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New thermal crosslinkers based on triazene: crosslinking of fluorinated polyimides and aromatic polymers

Cited by 14 publications

References 2 publications

Laser Application of Polymers

Laser Application of Polymers

Solubility improvements in aromatic polyimides by macromolecular engineering

Irradiation Wavelength Selective Surface Modification of a Triazeno Polymer

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