Ferrocene-Modified Block Copolymers for the Preparation of Smart Porous Membranes

Abstract

Abstract:The design of artificially generated channels featuring distinct remote-switchable functionalities is of critical importance for separation, transport control, and water filtration applications. Here, we focus on the preparation of block copolymers (BCPs) consisting of polystyrene-block-poly(2-hydroxyethyl methacrylate) (PS-b-PHEMA) having molar masses in the range of 91 to 124 kg mol −1 with a PHEMA content of 13 to 21 mol %. The BCPs can be conveniently functionalized with redox-active ferrocene moieties by a postmodification protocol for the hydrophilic PHEMA segments. Up to 66 mol % of the hydroxyl functionalities can be efficiently modified with the reversibly redox-responsive units. For the first time, the ferrocene-containing BCPs are shown to form nanoporous integral asymmetric membranes by self-assembly and application of the non-solvent-induced phase separation (SNIPS) process. Open porous structures are evidenced by scanning electron microscopy (SEM) and water flux measurements, while efficient redox-switching capabilities are investigated after chemical oxidation of the ferrocene moieties. As a result, the porous membranes reveal a tremendously increased polarity after oxidation as reflected by contact angle measurements. Additionally, the initial water flux of the ferrocene-containing membranes decreased after oxidizing the ferrocene moieties because of oxidation-induced pore swelling of the membrane.

Biomaterials Based on Carbon Nanotube Nanocomposites of Poly(styrene-b-isobutylene-b-styrene): The Effect of Nanotube Content on the Mechanical Properties, Biocompatibility and Hemocompatibility

“…Neat SIBS analyzed by SEM confirms the characteristic pattern of block-copolymers due to the microphase separation [ 41 , 42 ] ( Figure 3 a). The CNTs sheaves of different sizes were found in the fracture surface of nanocomposite films ( Figure 3 a).…”

“…Sample preparation upon fracture in liquid nitrogen allows preserving the molecular structure of the polymer nanocomposite [ 55 ]. The characteristic block copolymer pattern was observed both in pure SIBS and in the CNT-free regions of nanocomposites due to microphase separation ( Figure 3 a) [ 41 , 42 ] that indicates the preserving specific packing of the polymeric domains even after the reinforcing component addition. Fibrous structures that are visualized in the SIBS-CNT cross-section and have higher electron density (lighter in the SEM images) can be attributed to agglomerates consisting of several dozen individual tubes.…”

Amine-Containing Block Copolymers for the Bottom-Up Preparation of Functional Porous Membranes

“…Moreover, redox-responsive membranes were obtained by functionalization of PHEMA with switchable organometallic moieties. 36 A lot of effort has been carried out for postmodifying the hydrophilic block segment to widen the applications and switching capabilities of BCP membranes. 37−39 For example, Abetz and co-workers reported the successful coating of a PS-b-P4VP membrane with a polydopamine-based layer.…”

Ferrocene-Containing Polycarbosilazanes via the Alkaline-Earth-Catalyzed Dehydrocoupling of Silanes and Amines

“…Ferrocene-containing polymers often present interesting electrochemical properties due to the presence of multiple redox-active sites. ,, Using cyclic voltammetry, a brief and qualitative investigation was undertaken into the electrochemistry of the ferrocene-containing polycarbosilazanes. Polymer P1 displays a well-defined and fully reversible single electron redox process, corresponding to the Fe 3+ /Fe 2+ redox couple, with E 1/2 lying very close to that of the reference ferrocene redox system (Figure ).…”