Cobalt-Containing Polyimides for Moisture Sensing and Absorption

Abstract

A modified polyimide has been created that both senses and absorbs moisture. The material was prepared by introducing cobalt(II) chloride, a well-known moisture sensing and absorbing metal salt, into a polyimide. The final polymer was found to be fully cured, retaining the metal without any leeching, and was thermally stable. Furthermore, the material underwent a visible color change when exposed to moisture and reverted back to the original color when subsequently dried. The total moisture absorbed was measured with a quartz crystal microbalance. The amount of moisture absorption was found to be proportional to the relative humidity, and the modified polymer was found to have up to 3 times greater moisture absorption compared to the unmodified polymer.

Preparation and enhanced properties of Fe3O4 nanoparticles reinforced polyimide nanocomposites

“…[14][15][16] For example, cobalt-containing PI has been studied and applied for moisture sensing and absorption. [17] The well-dispersed hexagonal boron nitride (h-BN) composite films with oriented cross-linked liquid crystalline (LC) polyimide were obtained as high thermally conductive materials. [18] The PI has been used to fabricate pervaporation membranes for the separation of ethanol/water mixtures.…”

Insights into the physico-chemical behavior of CoCl2/polyimide hybrid materials

“…In addition, the intensities of the IR bands characteristic for aliphatic CH units increased when a higher content of CoCl 2 was used, which can be attributed to the incorporation of a certain amount of DMAc solvent molecules into the polymeric hybrid films, most probably coordinated by the Co 2+ ions [26]. The FTIR bands found at 2922 and 3380 cm −1 were associated with the absorption of the cobalt(II) chloride salt [20], since their intensities arise with the content of the salt. However, this band may overlap with the presumably absorption band determined by residual amide units.…”

“…CoCl 2 can easily coordinate water molecules, even in low humidity environments, along with the physical color change from blue to purple/pink. The water binding process was found to be reversible when the hydrated material is heated or placed under vacuum [19,20]. Therefore, it is expected that this metal halide filler will appreciably modify the structure and physical properties of the host polyimides, providing them with new and challenging properties.…”

Optical properties of polyimides films treated by nanosecond pulsed electrical discharges in water

“…Although PIs have been widely used in microelectronics and aerospace industries, their apparent color change from yellow to brown has limited their application in optical communication and photonic devices. [6][7][8][9][10][11][12] The coloration of polyimide was mainly attributed to intermolecular charge transfer (CT) complexes, owing to the molecular aggregation between PI chains in solid state. The fluorescence of PIs is also related to the intermolecular packing and CT nature, where aromatic moieties from diamine act as electron donors and imide moieties act as electron acceptors.…”

“…6) However, the insolubility of conventional PIs in organic solvents makes it difficult to distinguish the effects of intra-and intermolecular interactions. 5,8) Fully aromatic polyimides are known to exhibit fluorescence within the visible region, but the quantum yield of the fluorescence observed is relatively low owing to the strong CT nature of the polyimides and few studies were dedicated to applications of aromatic polyimides for electroluminescent devices. [10][11][12] On the other hand, fluorinated PIs have attracted much attention owing to the decrease in the degree of CT interaction caused by CF 3 -substituted diamines.…”