A novel approach for the synthesis of colloidal silver nanoprisms (AgNPrs) with controllable localized surface plasmon resonance (LSPR) via a chemical shape transformation of silver nanospheres (AgNSs) is presented. The shape conversion is carried out by feeding hydrogen peroxide (H 2 O 2 ) solution into a starchstabilized AgNS colloid under ambient conditions. Oxidative dissolution and the mild reducing action of H 2 O 2 under alkaline conditions serve as the principal reactions for the shape transformation process. After addition of H 2 O 2 , the instantaneous shape transformation events can be visualized by the naked eye through the color change of the colloid. Initial concentration of AgNSs, molar ratio of H 2 O 2 : AgNSs, H 2 O 2 injection rate, and mixing efficiency are the key parameters for controlling the LSPR wavelengths of AgNPrs as the in-plane dipole plasmon resonance can be selectively tuned across visible and near infrared regions (i.e., 460-850 nm). The obtained AgNPrs exhibited mixed geometries e.g. hexagonal, truncated triangular, rounded-tip triangular prisms, and circular disks with average bisector lengths of 30 to 120 nm and the thickness of 10 to 20 nm. A colloid of highly concentrated AgNPrs having a final concentration up to 11 mM can be produced within 10 min.

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Highly sensitive and accurate detection of hydrogen peroxide using starch-stabilized silver nanoprisms (AgNPrs) combined with image color analysis is proposed. The H2O2 concentration at 1.57 μM can be recognized by naked-eye observation.

The study on the shape evolution of metal nanoparticles (MNPs) is crucial to gain an understanding on controlling the shape and size of metal nanostructures. In this work, a detailed study on shape evolution of silver (Ag) nanospheres to nanoplates induced by hydrogen peroxide (H2O2) was performed. According to the growth mechanism of Ag nanoplates, the spectrophotometric method combined with chemometric analysis has potential to reveal the structural evolution process as observed by surface plasmon resonance phenomena. The extinction spectra of the evolving nanostructures were analyzed by factor analysis and error indicator functions. Five major components attributed to the different particle shapes and sizes were theoretically predicted. Furthermore, the concentration profiles and pure spectra of these components were resolved using multivariate curve resolution-alternative least squares (MCR-ALS) analysis. The evolution profiles show that the spherical Ag particles systematically evolved into plate structures of different sizes. Larger nanoplates were obtained when higher concentrations of H2O2 were employed. An evidence of nanoplate disintegration was observed when a large amount of H2O2 was employed. The predicted structural morphologies of each component given by chemometric calculation were in excellent agreement with those observed by transmission electron microscope (TEM) images.

Smart materials with light-actuated shape memory effects are developed from renewable resources in this work. Bio-based benzoxazine resin is prepared from vanillin, furfurylamine, and paraformaldehyde by utilizing the Mannich-like condensation. Vanillin-furfurylamine-containing benzoxazine resin (V-fa) is subsequently copolymerized with epoxidized castor oil (ECO). When the copolymer is reinforced with multiwalled carbon nanotubes (MWCNTs), the resulting composite exhibits shape memory effects. Molecular characteristics of V-fa resin, ECO, and V-fa/ECO copolymers are obtained from Fourier transform infrared (FT-IR) spectroscopy. Curing behavior of V-fa/ECO copolymers is investigated by differential scanning calorimetry. Dynamic mechanical properties of MWCNT reinforced V-fa/ECO composites are determined by dynamic mechanical analysis. Morphological details and distribution of MWCNTs within the copolymer matrix are characterized by transmission electron microscopy. Shape memory performances of MWCNT reinforced V-fa/ECO composites are studied by shape memory tests performed with a universal testing machine. After a significant deformation to a temporary shape, the composites can be recovered to the original shape by near-infrared (NIR) laser actuation. The shape recovery process can be stimulated at a specific site of the composite simply by focusing NIR laser to that site. The shape recovery time of the composites under NIR actuation is four times faster than the shape recovery process under conventional thermal activation. Furthermore, the composites possess good shape fixity and good shape recovery under NIR actuation.

In this research, shape memory polymers (SMPs) fabricated from bio-based benzoxazine resins, i.e. vanillin-furfurylamine-containing benzoxazine (V-fa) and eugenol-furfurylamine-containing benzoxazine (E-fa) resins, and bio-based epoxy resin, i.e. epoxidized castor oil (ECO), are investigated. Effects of ECO mass concentrations on curing characteristics, thermal stability, dynamic mechanical properties, and shape memory properties are determined by differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and shape memory tests, respectively. Storage moduli at the glassy state and glass transition temperatures (T g ) of V-fa/ECO and E-fa/ECO copolymers decrease with increasing ECO mass concentrations. The bending tests performed with a universal testing machine are employed to evaluate the shape memory properties of the developed bio-based copolymers. V-fa/ECO SMPs show excellent shape fixity of 86%-94% at room temperature and high shape recovery at T g +20 °C of 81%-96%. V-fa/ECO SMPs can undergo fold-deploy shape memory cycles without altering the shape memory performances for at least 5 cycles. Good balance between shape memory performances and thermo-mechanical properties in the V-fa/ECO copolymer system is obtained when ECO mass concentration is 40% (w/w).

Energy absorptions under ballistic impacts of aramid fiber-reinforced poly(benzoxazine-co-urethane) composites at urethane mass concentrations of 0, 10, 20, 30, and 40 wt.% were investigated. The energy absorption of the composite was investigated by subjecting eight plies of the specimen with 9 mm and .44 Magnum according to levels II and IIIA of the National Institute of Justice standard-0101.04. The composite having the urethane mass concentration of 20 wt.% exhibited the synergistic behavior in energy absorption at both levels II and IIIA. The 20 wt.% of PU composite also possessed the greatest tensile strength and modulus. The numerical prediction revealed that the ballistic limit of aramid fiber-reinforced poly(benzoxazine-co-urethane) ballistic panel was as high as 690 m s−1. High energy absorption capabilities of the composites can be tailored for fabricating the ballistic panels in soft armor applications.