Thermoselective permeation from a polymer-grafted capsule membrane

Abstract

Communications to the Editor Thermoselective Permeation from a Polymer-Grafted Capsule Membrane1,2 Permeability of microcapsules has been investigated rather extensively because of its importance in the design and construction of sustained drug release devices and artificial cells.3,4 In spite of its potential usefulness, the reversible, signal-receptive permeation control of the capsule has not been fully investigated.

Temperature-responsive permeability of porous PNIPAAm-g-PE membranes

“…27 Okahata et al developed pH-and temperatureresponsive polymer-grafted porous nylon capsule membranes with large diffusional permeability changes (up to a factor of 225). 3,28 They reported that the permeability response was not affected by graft yield ranging from 35 to 275% when hydrophobic poly(4-vinyl pyridine) was grafted. In contrast, when the graft polymer was relatively hydrophilic, the pH response decreased with increasing graft yield.…”

“…19,20 Temperature-, pH-or photosensitive polymers have been grafted onto porous substrates. [2][3][4][5]7,[11][12][13][14] The grafted polymers may be located mainly on the external membrane surface, 2,12 or they may be on the external surface as well as inside the pores, 4,7,14 depending on the grafting conditions. For example, in some reports of plasma-induced graft polymerization, active species for initiating are generated mainly near the membrane sur-face, resulting in preferential surface grafting.…”

“…18 Various types of membranes have been investigated, including homogeneous 1 and heterogeneous 6 hydrogels, membranes that contain liquid crystalline regions 9 or conductive polymers, 10 and porous membranes with grafted or adsorbed responsive polymer chains. [2][3][4][5]7,8,[11][12][13][14] One type of responsive membranes is prepared by grafting responsive polymers onto porous membrane substrates via various techniques. 2-5, 7,11-14 An advantage of such a membrane is that the porous substrate acts as a dimensionally stable matrix for mechanical support, while the conformational changes of the graft polymer induced by environmental stimuli lead to permeability changes.…”

Signal-responsive gating of porous membranes by polymer brushes

“…Apparently opposite temperature dependence of tryptophan permeation was found with these membranes. A number of signal-responsive polymer membranes have been prepared, but the mechanism of signal responsiveness was not made perfectly clear [26,46]. Although Iwata et al [47] and the author proposed a thermosensitive permeation mechanism, the explanations did not stand on the experimental results using the same material.…”

Thermo-Responsive Membranes with Cross-linked Poly(N-Isopropyl-acrylamide) Hydrogels inside Porous Substrates

“…Among the chemical techniques used to prepare thermo-responsive membranes, one of the most common methods is the grafting of thermo-responsive polymers onto porous membrane substrates by different grafting techniques, such as plasma induced grafting [1][2][3][4][5][6][7][8][9][10], UVor 60 Co c-radiation induced grafting [11-17, 30, 31, 43-45], and other chemical grafting methods [20]. Another chemical approach to prepare thermoresponsive membranes involves two steps, i.e., firstly fabricating the thermo-responsive polymers by chemical grafting, and then preparing membranes using the fabricated polymers by the phase inversion method [18,19].…”