Substituted propyne polymers—part II. Effects of aging on the gas permeability properties of poly[1‐(trimethylsilyl)propyne] for gas separation membranes

Abstract

Poly [ 1 -(trimethylsilyl)propyne] (PTMSP) is a n unusual polyyne material which is optically clear, exhibits high solubility in nonpolar organic solvents, and good oxygen compatibility. By contrast, polyacetylene is black, insoluble, and is unstable in oxygen. The long term stability of PTMSP has been determined by a combination of thermal gravimetric analysis (TGA) and permeability test procedures under a number of different isothermal aging conditions. The use of commercial antioxidants at up to 2 weight percent improves the long term stability of PTMSP. The presence of the antioxidant has no effect on the surface fluorination of PTMSP. Testing of PTMSP films for over eight months shows no change in either permeability or selectivity in contrast to previously reported data.Puratronic grade purchased from Alfa Inc., was PolymerizationPolymerization of PTMSP was carried out in a dry box as follows: TaC15 (0.5 g, 1.4m moles) was dissolved in 100 ml of toluene. The mixture was stirred for 30 min at room temperature. To this catalyst solution was added TMSP (12 g lOOm moles). The mixture immediately turned dark brown and the solution solidified within 30 min. After 24 h the polymerization mixture was worked up by precipitation of the polymer in rapidly stirred excess hot methanol. The polymer was washed several times with hot Purchased from Petrarch Systems Inc., was refluxed over CaHz under a nitrogen purge for 24 h and methanol and then dried to a constant weight. A yield of >95 percent was typically achieved by this process.

Effect of physical aging on the gas transport properties of poly(methyl methacrylate) membranes

“…Abundant evidences of realization of all phenomena are available in the literature. Poly[1-(trimethylsilyl)-1-propyne] (PTMSP) is an amorphous glassy polymer that reveals extremely great gas permeability, since the early studies of PTMSP, it was noted that its gas permeability undergoes fast reduction, when the membranes are stored in ambient atmosphere or in vacuum [9][10][11][12]. Annealing of the PTMSP membranes in vacuum, air and inert atmosphere accelerates the aging process [9].…”

A governing equation for physical aging of thick and thin fluoropolyimide films

“…[5][6][7][8][9][10] As an example, poly(trimethylsilylpropyne) (PTMSP), known as a glassy polymer with an extremely high excess free volume, was reported to undergo a rapid decrease of free volume and permeability over time. [11][12][13][14] In literature, there are arguably two mechanisms to explain such glass state volume relaxation phenomenon, namely, the free volume diffusion and the lattice contraction. [15][16][17][18][19][20][21] As first proposed by Alfrey et al, 17 the free volume in the form of holes or gaps will diffuse to the surface to accommodate the volume contraction, which is sample-size-dependent.…”

Physical Aging Phenomena in Poly(tert-butylacetylene) Solvent Cast Films: Influence of Operating Conditions

“…One of the major problems which limits the practical application of PTMSP in the field of polymer-based membranes, both for gas-separation and pervaporation processes, is the physical aging which occurs even at room temperature despite its high glass transition temperature (3,6, [9][10][11][12][13][14]. This has also been observed in PTBA (7).…”