Search results for "Polyimide"

New aromatic diamines containing a multiring flexible skeleton for the synthesis of thermally stable polyimides

2000

Abstract Multi-ring aromatic diamines bearing a long alkyl chain (C 6 , C 8 or C 16 ) were obtained from the corresponding dinitro compounds synthesized by a Friedel–Crafts alkylation of substituted mesitylenes by paranitrobenzyl chloride. The bismaleimide synthesized from the diamine bearing a C 16 chain formed a thermostable polyimide.

Atomic layer deposition of polyimide thin films

2007

The atomic layer deposition (ALD) of different polyimide thin films has been studied. We have demonstrated self-limiting ALD deposition of PMDA–DAH, PMDA–EDA, PMDA–ODA and PMDA–PDA thin films at 160 °C. The maximum deposition rate of 5.8 A cycle−1 was obtained for the PMDA–DAH process. Although the deposition rate was high at 160 °C, a sudden decrease was observed when the temperature was increased. Regardless of the process studied, no film growth was obtained at 200 °C or above. Deposited polyimide films were analysed by FTIR, AFM and TOF-ERDA. According to the FTIR measurements, imide bonds were formed already in as-deposited films indicating polyimide formation without any additional th…

Optical thermal filters for eXTP: manufacturing and characterization

2020

In order to ensure the effective detection of X-ray astronomical detectors by blocking ultraviolet, visible and infrared light, adding optical thermal filter in front of the load is an effective method. According to the scientific requirements of eXTP, optical thermal filters with aluminized polyimide (PI) film structure had been designed and tested in this paper, the results of mechanical tests including burst pressure, vibration and acoustic tests, also the transparent properties of optics in UV, Vis and IR lights are presented. The mechanical test results show that the filters for LAD and SFA can't pass the acoustic tests, causing the thickness of PI should be increased or a nickel mesh …

Thin film growth into the ion track structures in polyimide by atomic layer deposition

2017

Abstract High-aspect ratio porous structures with controllable pore diameters and without a stiff substrate can be fabricated using the ion track technique. Atomic layer deposition is an ideal technique for depositing thin films and functional surfaces on complicated 3D structures due to the high conformality of the films. In this work, we studied Al2O3 and TiO2 films grown by ALD on pristine polyimide (Kapton HN) membranes as well as polyimide membranes etched in sodium hypochlorite (NaOCl) and boric acid (BO3) solution by means of RBS, PIXE, SEM-EDX and helium ion microcopy (HIM). The focus was on the first ALD growth cycles. The areal density of Al2O3 film in the 400 cycle sample was det…

Analysis of measurements of stopping powers of formvar, polyimide, polysulfone, and vyns for 3.6 to 10.5 MeV7Li ions

2002

The stopping powers of formvar, polysulfone, polyimide, and vyns for 7Li projectiles have been measured with the transmission technique and thin foil targets. The experimental data have been analyzed in terms of modified Bethe–Bloch theory to extract characteristic values of the mean excitation energy and Barkas effect parameter, as well as to study the effects of including a single effective charge parameter. Results of this investigation are in general supportive of the outcomes of earlier similar studies with protons and α-particles traversing the same target materials in the sense that previously reported trends in projectile-dependent behavior of values of mean excitation energy and Ba…

1989

Polymides 3a and 3b with stiff-chains bearing trioxaoctyl or tetraoxaundecyl side chains were synthesized and characterized. The polycondensation was done with pyromellitic anhydride and N,N′-bis(1-imidazolylcarbonyl)-2,5-(1,4,7-trioxaoctyl)- or 2,5-(1,4,7,10-tetraoxaundecyl)-1,4-phenylenediamine (2a or 2b). 3b, being sufficiently soluble, was characterized by 13C NMR spectroscopy. The results of IR and 13C NMR spectroscopy prove the presence of the correct imide structure. In solid state 3a and 3b form layered structures with the side chains being in a disordered state.

Fine plastic foil as backing for sputtered nickel targets

2013

Targets of 58Ni and 60Ni with areal density between 71 and 105 μg/cm2 backed with polyimide foil of 35–40 μg/cm2 were prepared by sputtering with Ar ions produced by a home made sputtering device at the Target Laboratory, University of Jyväskylä. The efficiency of the procedure was about 20 %.

Iris-Like Tunable Aperture Employing Liquid-Crystal Elastomers

2014

A liquid-crystal elastomer (LCE) iris inspired by the human eye is demonstrated. With integrated polyimide-based platinum heaters, the LCE material is thermally actuated. The radial contraction direction, similar to a mammalian iris, is imprinted to the LCE by a custom-designed magnetic field. Actuation of the device is reproducible over multiple cycles and controllable at intermediate contraction states.

Networks of Partially Hydrogenatedcis-1,4-Polybutadiene and ‘Rigid Rods’

1996

Networks of 'flexible' and 'rigid' chains were synthesized. As 'flexible' component we have used different partially hydrogenated cis-1,4-polybutadiene. The 'rigid' component was synthesized from bis(1,2,4-triazoline-3,5-dione)s and biscyclohexadienes via repetitive Diels-Alder reaction. A slight excess of bis(1,2, 4-triazoline-3,5-dione)s leads to polymers with 1,2,4-triazoline-3,5-dione end groups, which can easily react with the partially hydrogenated cis-1,4-polybutadiene. The influence of the extent of hydrogenation and the amount of crosslinker on the mechanical and thermal behaviour is described.

Temperature effects on the performances of the ATHENA X-IFU thermal filters

2016

The X-Ray Integral Field Unit (X-IFU) detector on-board ATHENA is an array of TES micro-calorimeters that will operate at ~50 mK. In the current investigated design, five thermal filters (TF) will be mounted on the cryostat shields to attenuate IR radiative load and avoid energy resolution degradation due to photon shot noise. Each filter consists of a thin polyimide film (~50 nm thick) coated with aluminum (~30 nm thick). Since the TF operate at different temperatures in the range 0.05-300 K, it is relevant to study how temperature affects their mechanical/optical performances (e.g. near edge absorption fine structures of the atomic elements in the filter material). Such results are crucia…