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Fluoroalkenes are known to be notoriously reluctant substrates for olefin metathesis due to the generation of thermodynamically stable Fischer-type fluorocarbene intermediates, which invariably fail to undergo further reaction. In the present disclosure, we find that fluorine substitution on the sp 2 carbon also strictly suppresses homopolymerization of norbornene derivatives (NBEs), and this can be harnessed to achieve alternating ring-opening metathesis polymerization (ROMP) with an appropriately electron-rich comonomer. Dihydrofuran (DHF) is thereby shown to undergo alternating ROMP with fluorinated norbornenes, the perfectly alternating structure of the resulting copolymer having been unambiguously elucidated by 1 H, 19 F, and 13 C NMR analyses. Furthermore, we find that the degradability of the resultant copolymers in acidic media via hydrolysis of enol ether moieties in the backbone can be predictably modulated by the number of fluorine atoms present in the NBE comonomer, affording an opportunity to engage with the desirable physical properties of fluorinated polymers while limiting their attendant environmental degradability issues.

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A virtual button with tactile feedback is realized by use of ultrasonic vibration with amplitude of a few micrometers. Button-like click feeling is displayed by recreating rapid change in reaction force arising from buckling of a mechanical push button utilizing squeeze film effect. First, click feeling display system was constructed based on the principle of perceiving click feeling when pushing a mechanical button. In the system, stimulation are applied to the operators at both buckling and restitution point. Then, by conducting several sensory evaluation experiments, the optimum parameters of the ultrasonic vibration was determined to display button-like click feeling. Finally, by conducting usability test, it was verified that the usability of the virtual button was equivalent to that of a mechanical button.