Subnanometer hole properties of CO2-exposed polysulfone studied by positron annihilation lifetime spectroscopy

Abstract

Positron annihilation lifetime (PAL) spectroscopy has been employed to study subnanometer hole properties in polysulfone (PSF). In this study, hole properties of size, fraction, and distribution of PSF exposed to CO2 are reported. In the PSF/CO2 system, the hole size and fraction significantly increase and the free‐volume distribution broadens as a function of CO2 pressure in the range of 0–1000 psi. Hysteresis in hole properties is observed during CO2 sorption/desorption cycle. The high sensitivity of PAL results due to CO2 exposure in PSF is explained in terms of the microstructural changes in the polymer matrix, i.e., filling penetrant and plasticization, gas hydrostatic pressure effect, and creation of free volumes and holes. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3049–3056, 1998

Positron Annilation Lifetime and Glass Transition Temperatures in CO2Sorption Polystyrene

“…increase with T . The first observation of a negative free-volume thermal expansion coefficient at low temperature is similar to that reported in two systems, CO 2 exposed polycarbonate [14] and CO 2 exposed polysulfone [15] by us. There are a few possible processes for the free-volume variations with respect to the temperature in CO 2 /PS: (1) the expansion of the existing holes, (2) creating new holes, (3) re-arrangement of free volumes, (4) diffusion of CO 2 from the matrix and filling into the free volume, (5) collapsing the metastable free volumes, and (6) other effects, such as β-transition, etc.…”

“…PAL has been employed to study the CO 2 interaction with a few selected polymers, polyethylene (PE) [13], polystyrene (PS) [13], polysulfone (PSF) [14], and polycarbonate (PC) [15]. While PS have been extensively studied using PAL in recent years [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], for CO 2 exposure, only up to 50 psi has been reported [13].…”

Investigation on positron annihilation characteristics of CO2-exposed zeolite

“…There have been a lot of researches using many techniques that discuss the effect of plasticization caused by CO 2 on the variation of pore size (or free-volume) in membranes. Among of these techniques, the positron annihilation spectroscopy (PAS) technique is a sensitive probe for determining the average size and size distribution of pores [11][12][13][14][15].…”

Electron paramagnetic resonance spin probe study of carbon dioxide‐induced polymer plasticization

“…Our observation of double peaks with BzONO spin probe but not with DNOZ can be attributed to the relative sizes of the probes and the free volume voids. The average radius for a free volume void in the absence of plasticizer has been determined by positron annihilation spectroscopy to be 2.7 Å for PMMA68 and 2.6 Å for poly (vinyl chloride)69 and it is likely that PVAc and PEMA would have similar void sizes. In the presence of plasticizer, the average void size has been shown to increase from 2.6 Å (0% plasticizer) to 3.4 Å (35% dioctyl phthalate) in poly(vinyl chloride),70 and the void size and distribution of void sizes would also be expected to increase with plasticizer concentration in the polymers studied here.…”