Cryotropic hydrogels and their use as filters

Abstract

There is provided a particle-filter comprising at least one hydrogel formed in aqueous solution at a temperature below 0° C. The filter can arrest particulates of smoke by physisorption on the solid surface of the gel or by chemisorption if the gel is suitably functionalized. The effectiveness of filter in arresting the solid particles and the pressure drop can be controlled by varying the porosity and the pore size distribution of the filter which in turn can be modulated by varying the monomer to water and monomer to cross-linker ratio in the pre-polymer solution. The filter is able to reduce the particle content of the smoke. There is further provided a cigarette comprising at least one particle-filter according as well as a method for the filtration of smoke.

1 . A method of manufacturing a particle-filter, said particle filter comprising at least one hydrogel, said method comprising the step of forming the hydrogel in aqueous solution at a temperature below 0° C., wherein said particle filter is dried to an essentially dry condition, wherein the dried particle filter is ready to use as a particle filter. 
     
     
         2 . The method according to  claim 1 , wherein said particle-filter is a cigarette filter. 
     
     
         3 . The method according to  claim 1 , wherein said particle-filter is insoluble in water. 
     
     
         4 . The method according to  claim 1 , wherein said particle-filter is at least partially enclosed by paper. 
     
     
         5 . The method according to  claim 1 , wherein said particle-filter is supermacroporous. 
     
     
         6 . The method according to  claim 1 , wherein said particle-filter comprises at least one material selected from the group consisting of poly-acrylamide, agarose, and alginate. 
     
     
         7 . The method according to  claim 1 , wherein said particle-filter is formed at a temperature below −10° C. 
     
     
         8 . The method according to  claim 1 , wherein said particle-filter is formed without using any organic solvents.