Positron lifetime study of poly(dimethylsiloxane) based polymer-nanoparticle composites

16th International Conference on Positron Annihilation

Hughes, D.J.^1 ; Roussenova, M.V.^1 ; Beavis, P.^2 ; Swain, A.C.^2 ; Alam, M.A.^1

H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom^1

Atomic Weapons Establishment, Aldermaston, Reading RG7 4PR, United Kingdom^2

关键词: Loading level;    Local free volume;    Polydimethylsiloxane PDMS;    Polyhedral oligomeric silsesquioxanes;    Polymer nanoparticles;    Positron annihilation lifetime spectroscopy;    Positron lifetime study;    Temperature dependence;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/443/1/012045/pdf
DOI  :  10.1088/1742-6596/443/1/012045

来源: IOP

【 摘 要 】

Positron annihilation lifetime spectroscopy was employed to study the changes in the size of the local free volume elements (holes) of poly(dimethylsiloxane) (PDMS) based nanocomposites incorporating two different types of nanoparticles, meta-carborane (m-CB) and iso-octyl polyhedral oligomeric silsesquioxane (POSS). Materials were prepared with various loading levels of each nanoparticle and the temperature dependence of the o-Ps lifetime, and thus the free volume, and its distribution were measured from 100-300 K. It was observed that m-CB reduces the size of the local free volume elements while POSS has the opposite effect, in each case the change is only seen in the rubbery state below the so-called "knee temperature" (Tk∼ 210 K).