A refractometer based on fiber-to-liquid planar waveguide coupler

Extraordinarily large swelling energy of iodine‐treated poly(vinyl alcohol) demonstrated by jump of a film

“…The actuation stress of polymer gels reported to date is up to an order of 1 MPa. 19 A poly(acrylonitrile) gel fiber, for example, produces a contraction stress of about 2 MPa by changing pH. 20 The actuation stress of muscles is much lower and is in the range of 0.1-0.4 MPa.…”

“…These values are also greater than the actuation stress of 15 MPa and the gravimetric energy density of 1.6 3 10 2 J kg 21 reported for electroirradiated poly(vinylidene fluoride-trifluoroethylene) copolymer due to a giant electrostriction. 1 Figure 7 compares the levels of stress and strain generation for the iodine-treated PVA fibers and various actuation systems, including mechanical systems, on a map shown by Kim et al 19 The Gibbs free energy change at swelling consists of the energy change due to mixing, DG mix , and that due to strain, DG strain . The swelling takes place if DG mix is negative and larger in magnitude than DG strain which takes a positive value.…”

“…Comparison of the performance of iodine-treated PVA fibers with other actuation systems, including mechanical systems, on a map shown by Kim et al19 : (1) low strain piezoelectric, (2) high strain piezoelectric, (3) piezoelectric polymer, (4) thermal expansion (10 K), (5) magnetorictor, (6) thermal expansion (100 K),(7) shape memory alloy, (8) moving coil transducer, (9) solenoid, (10) muscle, (11) pneumatic,(12) hydraulic, (13) polymer gel, and(14)PAN actuator. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]…”