Ionic salts as anti-icing agents have been extensively used to eliminate accumulation of ice on asphalt surfaces. However, salt can be easily removed by rain or automobiles and requires frequent application on roads. Besides this economic consideration, anti-icing agents compromise the mechanical properties of asphalt and have a negative impact on living organisms and the environment when used in large amounts. Incorporation of hydrophilic salts into bitumen, a hydrophobic asphalt binder, and controlled release of specific molecules from this hydrophobic medium can provide an effective solution for reducing ice formation on pavements. Bitumen has previously been modified by various polymers, including styrene-butadiene-styrene (SBS) for improved strength and thermomechanical properties. However, an anti-icing function was not considered in those previous designs. In a previous study, we developed a functional polymer composite consisting of potassium formate (HCOOK) salt pockets dissolved in a hydrophilic gel medium and dispersed in a hydrophobic SBS polymer matrix. Here, we developed an innovative method to obtain polymer composite-modified bitumen and investigated further the anti-icing properties of the functional bitumen. We improved incorporation of this polymer composite into bitumen and demonstrated proper distribution of the composite within bitumen through morphological and rheological analysis. We characterized the anti-icing properties of modified bitumen surfaces and demonstrated significant increases in freezing delay of composite-modified bitumen compared to base bitumen in a temperature- and humidity-controlled chamber. In addition, we characterized the release of HCOOK salt from polymer composite-modified bitumen and observed salt release within the range of 1.07–10.8% (w/w) in 67 days, depending on the composite content. The results demonstrate the potential of this polymer composite-modified bitumen for anti-icing functionality and for industrially relevant applications.

Styrene-butadiene-styrene (SBS) triblock copolymer has been conventionally used as synthetic rubber. However, the potential of SBS for biomedical applications has only been considered in limited earlier reports. Here, we demonstrate an effective approach to designing a photocrosslinked SBS network. Rheological analysis has been conducted for the investigation of the storage modulus of the resultant network. Crosslinked SBS networks were synthesized and characterized through optical and electron microscope imaging. The crosslink density of the network, calculated from swelling experiments, was 643 mol m(-3), where higher swelling in a hydrophobic medium was observed compared to the swelling measured in water. Cell survival analysis with HeLa cells and NIH/3T3 fibroblasts revealed that these networks are non-toxic, and that they could be considered for a variety of biomedical applications.

Polymer composites consisted of small hydrophilic pockets homogeneously dispersed in a hydrophobic polymer matrix are important in many applications where controlled release of the functional agent from the hydrophilic phase is needed. As an example, a release of biomolecules or drugs from therapeutic formulations or release of salt in anti-icing application can be mentioned. Here, we report a method for preparation of such a composite material consisted of small KCOOH salt pockets distributed in the styrene-butadiene-styrene (SBS) polymer matrix and demonstrate its effectiveness in anti-icing coatings. The mixtures of the aqueous KCOOH and SBS-cyclohexane solutions were firstly stabilized by adding silica nanoparticles to the emulsions and, even more, by gelation of the aqueous phase by agarose. The emulsions were observed in optical microscope to check its stability in time and characterized by rheological measurements. The dry composite materials were obtained via casting the emulsions onto the glass substrates and evaporations of the organic solvent. Composite polymer films were characterized by water contact angle (WCA) measurements. The release of KCOOH salt into water and the freezing delay experiments of water droplets on dry composite films demonstrated their anti-icing properties. It has been concluded that hydrophobic and thermoplastic SBS polymer allows incorporation of the hydrophilic pockets/phases through our technique that opens the possibility for controlled delivering of anti-icing agents from the composite.

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