A series of semiaromatic polyimides containing polyhedral oligomeric silsesquioxane (POSS) in main chain (POSS−PIs) from a double-decker-shaped silsesquioxane diamine (DDSQ−diamine) (4) with various aromatic tetracarboxylic dianhydrides were prepared and the structures were characterized by IR and NMR spectra. A double-decker-shaped silsesquioxane dianhydride (DDSQDA) (3) was synthesized by hydrosilylation reaction from double-decker-shaped silsesquioxane (DDSQ) (1) and cis-5-norbornene-endo-2,3-dicarboxylic anhydride (2), which then reacted with 4,4‘-oxydianiline (ODA) to produce the DDSQ-diamine. The POSS−PIs possessed good thermal stability and mechanical properties, low water absorption, and alkali resistance as well as low dielectric constant. The 5% weight loss temperatures (T d 5) in air were observed at 495−514 °C. The polymer films had good mechanical properties with elongation at breakage of 2.9−6.0%, in which POSS−PI 8c derived from 4,4‘-oxydiphthalic anhydride (ODPA) exhibits the highest elongation of 6.0%. The water absorption of POSS−PI 8b (<1%) was much lower than that of PI from pyromellitic dianhydride (PMDA)/ODA (6.0%). POSS−PIs 8 possessed excellent alkaline and acid resistance. POSS−PI 8b kept its flexible mechanical properties when immersed in 5% NaOH solution at 40 °C for 72 h. The dielectric constant of POSS−PI 8c measured by precision impedance method was 2.36.

Preparation of low dielectric constant polyimides containing double-decker-shaped silsesquioxane (DDSQ) in the main chain with high molecular weights (η inh ) 0.61 dL/g) is reported. Double-decker-shaped silsesquioxane aromatic tetracarboxylic dianhydride (DDSQDA) was prepared by reaction of DDSQ aromatic diamine and pyromellitic dianhydride through functional group conversion method. The polyimides were synthesized from DDSQDA and several aromatic diamines by a one-step high temperature solution method. Introduction of DDSQ unit in polyimides endowed properties such as solubility in organic solvents, 10% weight loss temperatures (T d10 ) up to 570 °C in nitrogen, the glass transition temperatures (T g ) higher than 300 °C, good mechanical properties (tensile strengths of 72.3-82.1 MPa, initial modulus of 1.8-2.6 GPa, and elongation at breakage of 8.0-15.9%), transmittances over 80% at 400 nm, and a dielectric constant of 2.43 at 1 MHz. The polyimides were soluble in organic solvents such as DMAc, chloroform, THF, and acetone.

Studies on a resistive switching memory based on a silver‐ion‐conductive solid polymer electrolyte (SPE) are reported. Simple Ag/SPE/Pt structures containing polyethylene oxide–silver perchlorate complexes exhibit bipolar resistive switching under bias voltage sweeping. The switching behavior depends strongly on the silver perchlorate concentration. From the results of thermal, transport, and electrochemical measurements, it is concluded that the observed switching originates from formation and dissolution of a silver metal filament inside the SPE film caused by electrochemical reactions. This is the first report of an electrochemical “atomic switch” realized using an organic material. The devices also show ON/OFF resistance ratios greater than 105, programming speeds higher than 1 μs, and retention times longer than 1 week. These results suggest that SPE‐based electrochemical devices might be suitable for flexible switch and memory applications.

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