Influence of 1,2-PB Matrix Cross-Linking on Structure and Properties of Selectively Etched 1,2-PB-b-PDMS Block Copolymers

Abstract

A series of samples with varying cross-linking degree were prepared from the same 1,2polybutadiene-b-polydimethylsiloxane (1,2-PB-b-PDMS) diblock copolymer precursor. The stability of nanopores generated after PDMS cleaving depends on the cross-linking degree of 1,2-PB. The swelling ratio of the crosslinked samples in toluene was converted into a degree of cross-linking following the Flory scheme; a simple relation between the Flory cross-linking degree and the fraction of consumed double bonds during the crosslinking reaction followed. The structure of the block copolymer at different stages of preparation was characterized by small-angle X-ray scattering (SAXS). In addition, scanning electron microscopy (SEM) gave direct images of the nanoporous polymer structure. Nanocavities are accessible to methanol, and observations of methanol uptake were combined with structural information from SAXS. This permits a classification of the bulk cross-linked and etched polymers into three groups: collapsed, traced, and nanoporous materials.

UV patterned nanoporous solid-liquid core waveguides

“…The morphology of the self-assembled material is determined by the block's volume fraction in block copolymers and by thermodynamical variables [11][12][13]. In our work, the starting material is a self-assembled diblock copolymer of Polybutadiene and Polydimethylsiloxane (PB-PDMS) [ Fig.…”

“…Etching took 36 h and was followed by cleaning of the PB matrix in THF and methanol for a total of 16 h. A porosity of 0.44 [ Fig. 1(b)] was determined by methanol uptake [13] from the obtained material. The volume fraction of crosslinked PB (0.56) is lower than that of the uncrosslinked PB (0.60) due to increase of density induced by cross-linking.…”

“…1(b)]. Photo oxidation [17] in the presence of UV light (300-350 nm) changes the surface wetting property of the naturally hydrophobic 1,2-PB NP polymer [13]. The resultant hydroxyl and carboxyl groups on the matrix air interface, render the exposed region hydrophilic [ Fig.…”

Templating Nanoporous Polymers with Ordered Block Copolymers

“…56 The PB-PDMS material had a number-average molecular weight of 15.0 kg mol -1 , PDI of 1.22, and volume fraction of PDMS of 0.29. Following the synthesis of the parent PB-PDMS material, a series of eight cross-linked samples were prepared using dicumyl peroxide as a cross-linking initiator at 140°C under an argon atmosphere.…”

Transfer of Direct and Moiré Patterns by Reactive Ion Etching Through Ex Situ Fabricated Nanoporous Polymer Masks

“…Then, the 1,2-PB microphase is cross-linked to fix the structure and the PDMS microphase is selectively degraded. 22 The obtained monolith is a rigid cross-linked polybutadiene permeated by aligned hexagonally packed cylindrical nanopores with approximate volume fraction of 30%. Subsequently, the nanoporous polymer is sliced in a microtome obtaining sheets (or flakes) 70−300 μm across with thickness in the range of 30−60 nm.…”