## 3 HCL Polystyrene Based Nanocomposites
### Nanocomposites Containing Carbon-Based Nanostructured Fillers  
Nanostructured carbon materials, such as carbon nanotubes (CNT) and graphene, at first being mainly studied for their remarkable electronic, thermal, and mechanical properties [99], have soon been considered extremely attractive for their adsorption properties. Several researches have been focused on their adsorption properties, either for gas adsorption or for water purification [100; 101; 102; 103; 104; 105]. Filters based on CNT have been realized for purification of contaminated drinking water, which are able to electrochemically oxidize organic contaminants, bacteria, and viruses [106]. Depending on synthetic parameters, different interesting applications of nanostructured carbons are exploited. [PERSON] et al. [107] prepared sponges by graphene oxide processing that were able to adsorb different dyes, oils, and organic solvents from water. Graphene and graphene oxide (GO) interactions with organic substances in aqueous dispersion were studied by many research groups, and methylene blue (MB) adsorption, in particular, was exploited to correlate the amount of methylene blue adsorbed to the GO specific surface area [108; 109; 110; 111]. MB uptake was found to be increasing with increasing the oxidation degree of graphene oxide, while, for nano-graphene oxides that were prepared by a modified Hummers method, MB adsorption was found to be notably high, around 600-700 mg/g, almost indifferently from the oxidation level, probably due to the good stability of the nano-graphene oxide water dispersions, due to their reduced lateral size [112]. While considering the wide adsorption mechanisms of carbon-based nanostructured fillers, ranging from \(\pi\)-\(\pi\) interactions, hydrophobic effect, hydrogen bonds to electrostatic interactions [113], recently, in our research group, we investigated the interaction of such highly adsorbent materials with high surface area polymers as HCL styrene-based polymers. In particular, we prepared a new category of nanocomposites, based on a polymer phase made of DVB, ST and VBC and containing surface modified carbon nanotubes [114], graphene nanoplatelets (GNP), and surface modified graphene oxide [34], inspecting the structure, morphology, and adsorption properties of the obtained nanocomposites. In a first work, HCL polymers and nanocomposites based on DVB, ST, and VBC and containing multi-walled carbon nanotubes were prepared by a classical hyper-crosslinking two-step route, consisting in a suspension polymerization followed by Friedel-Crafts reaction [114]. The effect of CNT on nanocomposites with a different degree of hyper-crosslinking was explored by realizing polymers and nanocomposites that are composed of a polymeric matrix based on DVB, ST, and VBC in two different molar composition with a variable VBC content. In particular, a DVB/VBC system containing 2 mol % of DVB and 98 mol % of VBC, and a DVB/ST/VBC set of sample containing 2 mol % of DVB and 49 mol % of either ST and VBC, both containing up to 3 phr of CNT, were prepared. CNT were included in the monomeric matrices after proper surface grafting with poly(vinylbenzyl chloride) (PVBC) to promote the nanofiller inclusion and dispersion in the organic matrix, and to induce their participation to the hyper-crosslinking reaction. In fact, the functionalization strategy yields surface modified CNT with a layer of PVBC rich of unreacted chloromethyl groups that can be activated in the hyper-crosslinking step. CNT surface modification was effective to induce the inclusion of the nanofillers into the polymer beads, but, at higher loadings, the selective localization of the nanofiller became a relevant phenomenon (see Figure 8). The surface area analysis of the HCL polymers and nanocomposites revealed that the carbon nanotubes inclusion had a significant effect on the pore size distribution of the nanocomposites, leading to higher microporous fractions in the nanocomposites containing 1.5 phr of CNT.