One-Step Routes from Di- and Triblock Copolymer Precursors to Hydrophilic Nanoporous Poly(acrylic acid)-b-polystyrene

Abstract

Nanoporous polystyrene with hydrophilic pores was prepared from di- and triblock copolymer precursors. The precursor material was either a poly(tert-butyl acrylate)-b-polystyrene (PtBA-b-PS) diblock copolymer synthesized by atom transfer radical polymerization (ATRP) or a polydimethylsiloxane-b-poly(tert-butyl acrylate)-b-polystyrene (PDMS-b-PtBA-b-PS) triblock copolymer synthesized by a combination of living anionic polymerization and ATRP. In the latter copolymer, PS was the matrix and mechanically stable component, PtBA was converted by acidic deprotection to hydrophilic poly(acrylic acid) (PAA) providing at the same time part of the nanoporosity, and PDMS was quantitatively etched to provide additional nanoporosity. Both the deprotection of the PtBA block and the etching of PDMS were realized by one-step operations using either anhydrous hydrogen fluoride (HF) or trifluoroacetic acid (TFA). The finding that TFA can remove PDMS is important, not least as an alternative to the more hazardous HF. The investigated di- and triblock copolymer samples were of either hexagonal or lamellar morphology. The resulting nanoporous polymers were characterized by infrared spectroscopy, small-angle X-ray scattering, and scanning electron microscopy. In contact with water, all the prepared nanoporous polymers showed spontaneous water uptake close to the amounts expected from the precursor block copolymer compositions.

Gyroid Nanoporous Membranes with Tunable Permeability

“…18 We successfully generated a series of nanoporous polymers by selectively and quantitatively etching polydimethylsiloxane (PDMS) with anhydrous hydrogen fluoride, 14À16 trifluoroacetic acid, 14 or tetrabutyl ammonium fluoride.…”

Ultralow Friction with Hydrophilic Polymer Brushes in Water as Segregated from Silicone Matrix

“…Initially, PDMS-b -P t BA diblock copolymer was prepared by ATRP of tert-butyl acrylate ( t BA) from PDMS-Br macro initiator. [ 37 ] A clear shift of the SEC trace toward the lower elution volume ( Figure 1 A) and the narrow molecular weight distribution ( / w n M M = 1.23) verifi ed high macroinitiator efficiency. n M (p t BA) ≈ 10.6 kDa was determined by 1 H nuclear magnetic resonance (NMR) spectroscopy.…”

“…[ 34,36,37 ] It was then chain-extended by CuBr/ N , N , N´ , N″ , N″ -pentamethyldiethylenetriamine (PMDETA) mediated ATRP of t BA to obtain a well-defi ned diblock copolymer PDMS-b -P t BA. [ 37 ] Afterward tertbutyl protecting groups were removed by pyrolysis in a TGA instrument furnace resulting in PDMS(4.7)-b -PAA(6.1) (Scheme 1 , 2 ). [ 38 ] For comparison, PDMS(5.0)-b -PEG(2.1) ( 1-2 ) was purchased from Polymer Source Inc. (Montreal, Quebec, Canada) with a reported PDI of 1.16.…”

Nanomaterial with Variable d‐Spacing Prepared from Self‐Assembly of Cleavable Triblock Polystyrene‐(S2)Poly(tert‐butyl acrylate)–Polystyrene

“…And they also prepared PLA nanoporous material by metathesis degradation of polyolefin microphase . Vigild and co‐workers prepared nanoporous polystyrene with hydrophilic pores by deprotecting P t BA or etching PDMS of di‐ and triblock copolymer; Composto and co‐workers prepared amphiphilic nanostructures with stimuli‐responsive behavior from P t BA– b ‐PS by thermal deprotection of the tert ‐butyl groups. These well‐defined dispersed nano‐objects and nanoporous polymer materials have great potential applications in nanotechnologies related to delivery, loading, electronics, separation, etc.…”

“…On the other hand, the P t BA layers of the self‐assembly can be hydrolyzed into PAA layers in solid state of PS microdomains with the ordered structure well kept . Since the PAA layers show reverse response with change of pH and humidity, the d ‐spacing of the self‐assembly shrinks and expands accordingly like an accordion. This kind of material can show some visible color when the d ‐spacing fall in certain ranges, and then could be used as a indicator to show important information about the environment.…”