The block copolymers of poly(acrylic acid)-bpoly(vinyl alcohol) (PAA-b-PVA) were obtained from the hydrolysis of poly(methyl acrylate)-b-poly(vinyl acetate) (PMA-b-PVAc), which was synthesized by cobalt-mediated radical polymerization (CMRP) using the cobalt(II) porphyrin complex (Co II (TMP)) as the mediator. The mechanical properties of the PAA-b-PVA free-standing films could be tuned by the pH of the aqueous solution used to cast the films. The block copolymer films showed a much higher tensile strain and fractural tensile strength than the films prepared from the blends of PAA and PVA homopolymers. FTIR and morphological characterizations suggested that the tensile properties of the films were governed by both the hydrogen bonding between PVA and PAA that led to interpolymer complexation and the phase-separated morphology. For a given type of material, the greater extent of interpolymer complexation attained at lower solution pH led to the film with better tensile properties. The difference in the length scale of phase separation was responsible for the large difference in the tensile properties between block copolymer and blend films, where the characteristic nanostructure formed in the block copolymer prescribed a considerably larger amount of interface which enhanced the tensile properties significantly.

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a b s t r a c tAnalyzing radiation from material that has undergone neutron induced fission is important for fields such as nuclear forensics, reactor physics, and nonproliferation monitoring. The γ-ray spectroscopy of fission products is a major part of the characterization of a material's fissile inventory and the energy of incident neutrons inducing fission.Cumulative yields and γ-ray intensities from nuclear databases are inputs into a GEANT4 simulation to create expected γ-ray spectra from irradiated 235 U. The simulations include not only isotropically emitted γ-rays but also γ-γ cascades from certain fission products, emitted with their appropriate angular correlations. Here γ singles spectra as well as γ-γ coincidence spectra are simulated in detectors at both 901 and 1801 pairings.The ability of these GEANT4 Monte Carlo simulations to duplicate experimental data is explored in this work. These simulations demonstrate potential in exploiting angular correlations of γ-γ cascades in fission product decays to determine isotopic content. Analyzing experimental and simulated γ-γ coincidence spectra as opposed to singles spectra should improve the ability to identify fission product nuclei since such spectra are cleaner and contain more resolved peaks when compared to γ singles spectra.

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