Ecological disasters resulting from oil spills have created a great need to find more efficient materials for oil spill cleanup. This research highlights the use of a novel macroporous polymeric material based on butyl rubber (BR) as a sorbent in an oil spill cleanup. The sorption capacity of BR for crude oil and petroleum products is 15-23 g g(-1) as compared to the value of 10-16 g g(-1) obtained using a nonwoven polypropylene (PP), a widely used commercial oil sorbent. BR sorbent is reusable after simple squeezing and its continuous sorption capacity for crude oil is 7.6 g g(-1) in each cycle, about 3 times the capacity of the PP sorbent BR sorbents also remove efficiently polycyclic aromatic hydrocarbons (PAHs) such as acenaphthene and pyrene from seawaters. The results suggest that the rubber sorbents are a better alternative to the widely used PP sorbents by improving the efficiency of oil sorption and the reusability of the sorbent.

Macroporous gels were prepared by solution crosslinking of butyl rubber (PIB) in frozen benzene solutions using sulfur monochloride (S2Cl2) as a crosslinking agent. The effect of different preparation conditions, including the crosslinker concentration and the gel preparation temperature, on the gel properties was investigated. S2Cl2 was found to be an efficient crosslinking agent even at very low reaction temperatures up to −22 °C and at crosslinker ratios down to about 0.9 mol S2Cl2/mol internal vinyl group on PIB. The gels prepared from frozen solutions of PIB contain about 97% organic liquid, and they are very tough; they can be compressed up to about 100% strain without any crack development, during which the total liquid inside the gel is removed. Further, the compressed gel immediately swells in contact with good solvents to recover its original shape. The low-temperature gels have a porous structure with irregular large pores of 101−102 μm in diameter, separated by pore walls of about 10 μm in width with a high polymer concentration, which provide structural support to the material. The gels also exhibit completely reversible swelling−deswelling cycles in toluene and methanol, respectively, i.e., they return to their original shape and original mass after a short reswelling period. The results suggest that both phase separation of PIB chains at low temperatures and the presence of frozen benzene templates are responsible for the porosity formation in PIB gels.

A series of ionic poly(acrylamide) (PAAm) gels was prepared by free-radical crosslinking copolymerization of acrylamide and N,NЈ-methylenebisacrylamide in aqueous solutions. The gels were prepared both below and above the bulk freezing temperature of the polymerization solvent water, which are called as the cryogels and the hydrogels, respectively. The deswelling behavior of swollen gels in acetone as well as the reswelling behavior of the collapsed gels in water were investigated. It was shown that the cryogels respond against the external stimuli much faster than the hydrogels. The interior morphology of the cryogel networks exhibits a discontinuity and a two-phase structure, compared to the continuous morphology of the hydrogel networks. Introduction of the ionic units in the network chains further increased the response rate of the cryogels. In contrast to these advantages of cryogels, they exhibit lower swelling capacities than the conventional hydrogels.

Aerogels are structural materials with ultralow bulk densities (often less than 0.1 g cm -3 ), which stand out as good candidates for a variety of applications. In the present study, natural rubber (NR)/ clay aerogel composites were produced by freeze-drying of the aqueous aerogel precursor suspensions, followed by solution cross-linking of the aerogel samples in benzene using sulfur monochloride (S 2 Cl 2 ) as a cross-linking agent. The influences of cross-linking conditions, i.e., cross-linker concentration and reaction temperature, as well as polymer loading on the aerogel structure and properties were investigated. 1% (v/v) of S 2 Cl 2 and reaction temperature of -18°C were found to be the optimum conditions for producing a strong and tough rubber composite; the 2.5 wt % NR aerogel, for example, after being cross-linked, exhibited a compressive modulus of 1.8 MPa, 26 times higher than that of the neat control. These favorable mechanical properties are attributed to the high local concentration of rubber and S 2 Cl 2 in the freeze-dried structures, giving rise to the high cross-linking efficiency. Increasing the rubber concentration led to a substantial increase in the mechanical strength, in accord with the changes in microstructure and degree of cross-linking. The swelling capacity of the NR aerogels decreased with either increasing the cross-linker concentration or decreasing the weight fraction of rubber. Cross-linking of the rubber aerogels brought about increased thermal stability, consistent with restricted thermal motion of NR chains.

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