Highly Stretchable and Rapid Self-Recoverable Cryogels Based on Butyl Rubber as Reusable Sorbent

Abstract

Cryogels based on hydrophobic polymers combining good mechanical properties with fast responsivity are attractive materials for many applications, such as oil spill removal from water and passive sampler for organic pollutants. We present, here, cryogels based on butyl rubber (BR) with a high stretchability, rapid self-recoverability, and excellent reusability for organic solvents. BR cryogels were prepared at subzero temperatures in cyclohexane and benzene at various BR concentrations in the presence of sulfur monochloride (S2Cl2) as a crosslinker. Although the properties of BR cryogels are independent of the amount of the crosslinker above a critical value, the type of the solvent, the cryogelation temperature, as well as the rubber content significantly affect their properties. It was found that benzene produces larger pore volumes as compared to cyclohexane due to the phase separation of BR from benzene at low temperatures, producing additional pores. Increasing cryogelation temperature from −18 to −2 °C leads to the formation of more ordered and aligned pores in the cryogels. Increasing BR content decreases the amount of unfrozen microphase of the frozen reaction solution, leading to a decrease in the total porosity of the cryogels and the average diameter of pores. Cryogels formed at −2 °C and at 5% (w/v) BR in cyclohexane sustain up to around 1400% stretch ratios. Cryogels swollen in toluene can completely be squeezed under strain during which toluene is released from their pores, whereas addition of toluene to the squeezed cryogels leads to recovery of their original shapes.

Structural Diversity in Cryoaerogel Synthesis

“…Decreasing the temperatures of the cooling medium lead to faster freezing of samples and a lower degree of orientation within the ice template. 37 As already discussed, slower freezing (at higher temperatures) results in aligned and lamellar shapes ( Figure 5 a-b). With faster freezing, on the other hand, more and smaller ice crystallites are formed.…”

Field Study for PAH Absorption Performances of Butyl Rubber, PDMS, and SPMD Passive Samplers

“…BR passive samplers with single network (SN5 and SN10), double network (DN), and triple network (TN) structures were fabricated as detailed before (Muslumova et al 2019). Brie y, to prepare SN5 and SN10 passive samplers, 5 and 10 g puri ed BR was rst dissolved in 100 mL benzene at room temperature overnight, to obtain 5 and 10 w/v% BR solutions respectively.…”

Cryogels: recent applications in 3D-bioprinting, injectable cryogels, drug delivery, and wound healing

“…It has been found that decreasing the pore size will increase the compressive strength [ 26 ], though in contrast to this Dispinar et al found that increased porosity resulted in higher compressive stresses being achieved. Further to this, compressive strain was found to increase with porosity [ 25 ], suggesting that the brittle nature observed for some hydrogels may be due to their lack of macropores [ 27 – 28 ]. One such application where a low compressive strain would not be desirable is if the cryogel was to be injectable (see section 5.2).…”