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MAHMOUD, Kamal Reyad; EL-SHEHAWY, Ashraf  and  ATTA, Hoda. Positron annihilation spectroscopy of chain-end-functionalized polystyrenes with definite numbers of benzyl alcohol and perfluorooctyl groups. Polímeros [online]. 2019, vol.29, n.4, e2019046.  Epub Apr 27, 2020. ISSN 1678-5169.

A series of well-defined chain-end-functionalized polystyrenes with a definite number of benzyl alcohol and perfluorooctyl groups [PS(BnOH)n & PS(BnORf)n, respectively] linearly aligned in a double line at the chain-ends were prepared and investigated using XRD, SEM, PALS and DBAR spectroscopy. XRD studies showed that PS(BnOH)n are crystalline and the degree of crystallinity increases with increasing the number of benzyl alcohol functionalities, while XRD pattern of PS(BnORf)n revealed that incorporating perfluorooctyl groups resulting in some fractions of polystyrene chains that were intercalated or broken between the interlayer spacing. PALS measurements yielded three lifetime components and the formation probabilities as well as lifetime of ortho-positronium in polymer series were found to be dependent on the chain-end polymer structure. DBAR measurements suggested that only one type of defect is present in the polymer samples.

Keywords : benzyl alcohol and perfluorooctyl groups; hyperbranched polymers; chain-end-functionalized polystyrene; doppler broadening; free volume; positron annihilation.

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