Polyelectrolyte Multilayers on PTMSP as Asymmetric Membranes for Gas Separations: Langmuir–Blodgett versus Self-Assembly Methods of Anchoring

Abstract

Polyelectrolyte multilayers derived from poly(diallyldimethylamonium chloride) and poly(sodium 4-styrenesulfonate) have been deposited onto poly[1-(trimethylsilyl)-1-propyne] (PTMSP) with anchoring layers formed by Langmuir-Blodgett and self-assembly methods. Using gas permeation selectivity as a basis for judging the efficacy of each anchoring method, we have found that similar CO2/N2 selectivities (ranging from 110 to 140) could be achieved by both methods and that their permeances were also similar. Although LB anchors require fewer layers of polyelectrolyte to reach this level of selectivity, the greater ease associated with self-assembly and its applicability to curved, high-surface-area supports (e.g., PTMSP-coated hollow fibers) encourage its use with PTMSP in creating new membrane materials for the practical separation of gases.

Hyperthin Membranes for Gas Separations via Layer‐by‐Layer Assembly

“…Because self‐assembly methods are much simpler (e. g., adsorbing a monolayer of branched poly(ethyleneimine), b ‐PEI onto PTMSP), we carried out a detailed study to determine whether there were any advantages to the more laborious LB method. Thus, a Langmuir‐Blodgett monolayer of a poly(1‐octadecene‐alt‐N,N,N‐trimethylammonium‐N‐ethylmaleimide) chloride (POMTMA) was compared with a self‐assembled monolayer of branched poly(ethyleneimine) ( b ‐PEI) as anchor layers, using PEMs formed from PDDA and PSS as a test case (Figure ) . In this study, we found that similar CO 2 /N 2 selectivities (ranging from 110 to 140) and similar permeances were obtained using both types of anchors.…”

Splaying hyperthin polyelectrolyte multilayers to increase their gas permeability

“…11.5 nm). 15 nm, all of the membranes investigated [i.e., (PSS-PAH) 10.5 , (PSS-1c) 13.5 , (PSS-1b) 12.5 and (PSS-1a) 11.5 ] exhibited similar permeation selectivities (ca. Addition of three bilayers of PSS-1c to produce (PSS-1c) 13.5 led to a further reduction in permeability and an increase in permeation selectivity.…”

“…Polyelectrolyte multilayers that were fabricated from 13.5 bilayers of PSS and PAH (i.e., [PSS-PAH] 13 To assess their permeability properties, hyperthin PEMs made from PSS plus PAH, 1a, 1b or 1c were deposited onto cast films of poly[1-(trimethylsilyl)-1-propyne] (PTMSP) that were surface-modified b-PEI. 13 In Table 1 are listed the permeances (P/l) that were observed with respect to H 2 and N 2 .…”

“…Addition of three bilayers of PSS-1c to produce (PSS-1c) 13.5 led to a further reduction in permeability and an increase in permeation selectivity. 11.5 nm).…”

Ultrathin Composite Polymeric Membranes for CO2/N2 Separation with Minimum Thickness and High CO2 Permeance

“…To obtain ultrathin layers of PIM, we considered the Langmuir-Blodgett (LB) technique [8] which can be used for the deposition of polymeric layers on top of different kinds of supports to produce composite membranes.B yu sing this approach,LBfilms formed by different surfactants have been previously deposited onto poly[1-(trimethylsilyl)-1-propyne] (PTMSP) substrates to enhances electivities for H 2 /CO 2 [9] and CO 2 /N 2 [10] separations. Ultrapermeable PTMSP films have also been used as support for the deposition of metal-organic covalentn etworks by chemical vapor deposition for gas separation membranes.…”