A New Approach To Microporous Materials — Application Of Ion Beam Technology To Polyimides Membrane

Abstract

Recently engineered porous materials have been attracted more attentions because of their potential applications in several industrial sectors, such as high efficiency gas separation membrane, catalytic membranes for chemical processing and so on. In spite of their desirable applications, these porous materials have not been realized due to several technical barriers, for example, lack of pore size control. There is a general viewpoint that for conventional gas separation membranes one cannot increase both permeability and permselectivity of the product gas simultaneously. This general viewpoint implies that the conventional methods of gas separation membrane fabrication cannot precisely control the pore size. In this work iodine diffusion property and gas permeation properties of ion beam irradiated polyimides films have been investigated. Small fluence irradiation can raise significantly the iodine penetration in the energy deposition range and permeabilities of the films both for H2 and CH4. After higher fluence irradiation, the implanted layers become stopping layers blocking iodine diffusion into the film and both the permeability for H2 and permselectivity for (H2/CH4) of the film increase hugely. We related the small fluence effects to defects created by irradiation and higher dose effects to the new materials formation of which the pore size is well defined. From these results we can perhaps have a peep at a new way to microporous materials.

Polymer evolution of a sulfonated polysulfone membrane as a function of ion beam irradiation fluence

“…Ion beam irradiation has long been recognized as an effective method for the synthesis and modification of [2][3][4]. Ion beam irradiation is the bombardment of a substance with energetic ions.…”

Impact of H+ ion beam irradiation on Matrimid®. II. Evolution in gas transport properties

“…[16][17][18][19][20][21][22][23][24] When an energetic ion penetrates a polymer surface, it transfers its energy to the polymer backbone. There are essentially two energy transfer mechanisms from the incident ion to the polymer for the ion energy used in this study 25 : (i) electronic energy loss, which involves electronic excitation and exchange of electrons between incident ions and the polymer, and (ii) nuclear energy loss, which involves atomic collision between ions and atoms in the polymer.…”

Pulsed ion beam irradiation effects on surfaces of polymeric materials

“…It was noted that the adhesion of polymers could be improved [1,2], the wettability influenced [1], or polymers with improved hardness and reduced friction coefficients could be obtained due to ion implantation [3,4]. Similarly, it was suggested that ion implantation could be beneficial for producing microporous gas-selective polyimide membranes [5] or for specific modifications of polymers used in optical applications [6]. The degradation occurring during ion beam irradiation has been investigated in several studies [7][8][9][10][11], and the erosion of polymer surfaces by high energy ions or particles, which occurs in low Earth orbit, is of interest for polymers used in space vehicles [12,13].…”