## 1 Introduction  
The concept of polymer chain hypercrosslinking was introduced by [PERSON], [PERSON] and [PERSON], using linear polystyrene or swollen gel-type poly (styrene-co-divinylbenzene) in the presence of an external crosslinker, solvent and a Lewis base as a catalyst [1]. The result of the reaction was a three-dimensional rigid network with short and rigid connections. Generally, hypercrosslinked polymers are prepared by post-polymerisation crosslinking of long polymer chains in a swollen polymer matrix creating numerous new links. In the case of chloromethylal polystyrene, polymer chains are reacted with a Friedel-Crafts catalyst in a swelling solvent. This creates new connections by converting chlorophyll groups into methylene bridges that interconnect polymer chains resulting in the formation of micropores. Through further stages of the hypercrosslinking process, the crosslinking increases and, therefore, after solvent removal, a stable microporous network is formed [2, 3]. The hypercrosslinked polymers may collapse during drying however reinforcement of their skeleton with additional crosslinks enables their re-expansion both with polar and non-polar solvents [4, 5]. Hypercrosslinked polymers contain a very high density of crosslinks together with micropores and exhibit high surface area (up to 2000 m\({}^{2}\)/g) [4, 6]. The main difference between a post-polymerisation hypercrosslinking and copolymerisation crosslinking is in the pore formation method. In copolymerisation crosslinking,pores are formed due to phase separation during polymerisation between the monomer and the crosslinker, in the presence of an inert diluent. The result is the formation of a two-phase heterogeneous system where one phase represents a crosslinked polymer and the other excess diluent and possibly unpolymerised monomers. Usually, phase separation occurs near the gel point and can appear as macrosyneresis [7] when the fluid and a swollen gel make two continuous phases. Resulting macroreticular polymers have a cauliflower-like morphology [8; 9; 10], with pores as spaces in clusters of crosslinked polymer nodules. Such polymers usually exhibit relatively modest specific surface area and somehow poorer mechanical stability [11] than their gel-type counterparts do. Post-polymerisation crosslinking--hypercrosslinking performed on swollen polymers induces the formation of additional porosity and increases rigidity of the polymer matrix which improves its compatibility with both thermodynamically good and bad solvents [5; 12] and thus improve the accessibility of reactive sites. Therefore, hypercrosslinked polymers are used as separation columns [13; 14; 15; 16], adsorbents [17; 18; 19; 20; 21], solid state supports for catalysts [22; 23; 24], to name the most frequent applications. On the other hand, macroporous polymers in monolithic form can be obtained by the polymerisation of a continuous phase of high internal phase emulsion (polyHIPE) [25; 26; 27; 28]. The internal (or droplet) phase is dispersed in the continuous phase of the emulsion and represents at least 74.05% of the total volume of the emulsion in the uniform packing of monodispersed droplets, or 64% in the case of random packing [29]. Most common are water-in-oil HIPEs, where the continuous phase consists of monomers, surfactants and initiator, while the internal phase is aqueous. After the polymerisation of the continuous phase, the droplet phase is removed, and macro pores are thus formed. The internal topology of polymeric material prepared in this way has two levels of pores, the primary pores, and secondary, interconnecting pores. PolyHIPEs have so far found numerous applications such as tissue engineering [30; 31; 32; 33], as columns in separation systems [34; 35; 36; 37; 38], as supports for catalysts [6; 39; 40] etc. Hypercrosslinking of 4-vinylbenzyl chloride (VBC)-based polyHIPEs results in rigid polymers with induced microporosity in macro porous material, which leads to very high specific surface areas and better compatibility with solvents.