High Fidelity Tape Transfer Printing Based On Chemically Induced Adhesive Strength Modulation

Transfer printing, a two-step process (i.e. picking up and printing) for heterogeneous integration, has been widely exploited for the fabrication of functional electronics system. To ensure a reliable process, strong adhesion for picking up and weak or no adhesion for printing are required. However, it is challenging to meet the requirements of switchable stamp adhesion. Here we introduce a simple, high fidelity process, namely tape transfer printing(TTP), enabled by chemically induced dramatic modulation in tape adhesive strength. We describe the working mechanism of the adhesion modulation that governs this process and demonstrate the method by high fidelity tape transfer printing several types of materials and devices, including Si pellets arrays, photodetector arrays, and electromyography (EMG) sensors, from their preparation substrates to various alien substrates. High fidelity tape transfer printing of components onto curvilinear surfaces is also illustrated

Hard and Flexible, Degradable Thermosets from Renewable Bioresources with the Assistance of Water and Ethanol

A carboxylic acid functional trimer made from the reaction of isosorbide with maleic anhydride was used to cross-link epoxidized sucrose soyate (ESS), resulting in bio-based, degradable thermosets having a good combination of hardness and flexibility. This work addresses some critical needs for thermosets such as improving the sustainability of raw materials, enabling recycling, and achieving both good material hardness and flexibility/ductility simultaneously. In this paper, a dicarboxylic acid, MI, was synthesized from isosorbide and maleic anhydride and characterized in detail by FTIR and H-1 NMR It was utilized to cross-link ESS without using extra catalyst or toxic compounds except for ethanol and water. For comparison, a dicarboxylic acid from 1,3-propanediol and maleic anhydride (MP) was also synthesized and used to cross-link ESS. Because of the carbon carbon double bond in conjugation with the carboxylic acid group, both MI and MP showed high reactivity toward ESS and could cross-link ESS with the assistance of water and ethanol. The MI cross-linked thermosets exhibited superior thermal and mechanical properties and excellent coating performance including a high level of flexibility (reverse impact >168 in.-lb and elongation at break from mandrel bend >28%), adhesion (5B), and solvent resistance as well as high hardness (Konig pendulum hardness 189 s). The thermosets could be degraded and completely dissolved in NaOH aqueous solution at 50 degrees C-as fast as 10 min but they are stable in an HCl aqueous solution at 50 degrees C. The thermosets could also be thermally degraded