Hypercrosslinked materials: preparation, characterisation and applications

Abstract

11This review article provides an overview of hypercrosslinking technology. In particular, it 12 covers the preparation and characterisation of hypercrosslinked materials and their 13 applications. The synthesis section examines the different monomers, precursor polymers and 14 reagents used to prepare hypercrosslinked materials, but also the different synthetic 15 approaches disclosed in the literature. The various chemical modification reactions relevant to 16 this area are also reviewed. 17Several examples of applications for hypercrosslinked materials are described; these 18 applications are grouped into thematic areas such as chromatography, gas storage and the 19 trapping of organic contaminants. 20 21 3 as a whole, but draw particular attention to the innovations and developments which have 55 come out of the Sherrington research group over the past years. 56 SYNTHETIC APPROACHES 57Originally, HXL networks were obtained via the post-crosslinking of polystyrenic 58 chains/structures in an expanded/swollen state by using external crosslinkers. These external 59 crosslinkers bridge between adjacent aromatic residues, setting in place short, rigid 60 (hyper)crosslinks, and these are very often installed through F-C reactions. Figure 1A shows the 61 different steps involved during a post-crosslinking reaction of PS. The structure of a typical HXL 62 polymer is a rigid and expanded three-dimensional network. The main structural element of 63 this network is a spatially non-planar cycle formed by crosslinking bridges, and very short chain 64 segments confined between the branching points. By using an external crosslinker together 65 with a F-C catalyst almost all of the aromatic rings can be crosslinked/bridged and ultra-high 66 SSAs achieved. The resulting hypercrosslinked network displays a high degree of crosslinking, 67

Fibers with Hyper‐Crosslinked Functional Porous Frameworks

“…With the formation of more and more structural bridges, the peaks at 672 and 818 cm −1 became gradually less intense as a result of the CCl bond breakage and the transformation of para‐substituted benzene rings to multisubstituted ones. The peak at 2976 cm −1 in all hyper‐crosslinked samples (denoted as VBC@PE–HXL) was attributed to the formation of a six‐membered ring through the cyclisation of two benzyl chloride bonds . As expected, the vibrations of the –CH 2 – backbone (e.g., 2916, 2848, and 719 cm −1 ) became weaker, owing to the increasing numbers of dark crosslinked VBC layers that covered the PE surface and blocked the IR beam, rather than to damage to the PE core structure.…”

Comparative study of strong anion exchange hypercrosslinked poly(HEMA-co-EGDMA-co-VBC) and strong anion exchange poly(Styrene-co-EGDMA-co-VBC): Synthesis and characterization

“…For PSEV, the precursors were easier to swell in solvent during hypercrosslinking reaction compared to macroporous PHEV due to small amount of crosslinker presence in precursor.This causing more chloromethyl group being transformed to methylenebridge and subsequently formed pores. 15 However, for PHEV, the precursor containing high amount of crosslinker resulting the particles more rigid and less swell in solvent. This contributes to less conversion of chloromethyl group to methylene bridges.…”

Oil Sorbents based on Methacrylic Acid - Grafted Polypropylene Fibers: Synthesis and Characterization

“…It turns out that in the beginning, the oil sorption capacity increased and reached a maximum level of 19.5 g/g with DVB concentration went up to 1.5%, but beyond this it fell down. This result can be explained as follows: a strong rising concentration of DVB causes a serious increased cross-linking level as well as a high density network, which reduces the space inside the gel, restricts the ability of the network to expand, therefore resulting in a decreased oil sorption capacity of the material [50,51].…”