Hydrogels that undergo volumetric expansion in response to changes in their environment and their methods of manufacture and use

Abstract

Hydrogels are described that expand volumetrically in response to a change in their environment and as well as their methods of manufacture and use.

We claim: 
     
         1 . An environmentally responsive hydrogel comprising:
 a base treated acrylic polymer having de-protonated amine functional groups comprising a reaction product of environmentally responsive monomers or prepolymers and a multifunctional crosslinker,   wherein said environmentally responsive hydrogel is dry and wherein the environmentally responsive hydrogel has a controlled rate of expansion at physiological pH.   
     
     
         2 . The environmentally responsive hydrogel of  claim 1  wherein the environmentally responsive hydrogel is subjected to a basic bath to form the environmentally responsive monomers or prepolymers having de-protonated amine functional groups. 
     
     
         3 . The environmentally responsive hydrogel of  claim 1  wherein the hydrogel expands as the surrounding pH decreases. 
     
     
         4 . The environmentally responsive hydrogel of  claim 1  wherein the base treated acrylic polymer having de-protonated amine functional groups comprises a reaction product of a mixture comprising the environmentally responsive monomers or prepolymers and the multifunctional crosslinker. 
     
     
         5 . The environmentally responsive hydrogel of  claim 1  wherein the multifunctional crosslinker is biodegradable. 
     
     
         6 . The environmentally responsive hydrogel of  claim 1  wherein the environmentally responsive hydrogel is biodegradable. 
     
     
         7 . The environmentally responsive hydrogel of  claim 1  wherein the multifunctional crosslinker is N,N′-methylenebisacrylamide. 
     
     
         8 . The environmentally responsive hydrogel of  claim 1  wherein the hydrogel has a pore size of less than about 25 μm. 
     
     
         9 . The environmentally responsive hydrogel of  claim 1  wherein the hydrogel has a pore size of less than about 10 μm. 
     
     
         10 . The environmentally responsive hydrogel of  claim 1  wherein the environmentally responsive hydrogel is non-porous. 
     
     
         11 . The environmentally responsive hydrogel of  claim 1  further comprising radiopaque monomers. 
     
     
         12 . The environmentally responsive hydrogel of  claim 1  wherein the environmentally responsive hydrogel has a shape selected from pellets, elongated filaments or particles. 
     
     
         13 . The environmentally responsive hydrogel of  claim 1  wherein the environmentally responsive hydrogel is delivered to a physiological environment through a catheter. 
     
     
         14 . The environmentally responsive hydrogel of  claim 13  wherein the catheter has a lumen with a diameter of 0.005 inch to 0.050 inch. 
     
     
         15 . The environmentally responsive hydrogel of  claim 1  wherein the controlled rate of expansion at physiological pH lasts for up to 15 minutes. 
     
     
         16 . The environmentally responsive hydrogel of  claim 1 , wherein the base treated acrylic polymer comprises a reaction product of a mixture comprising the environmentally responsive monomers or prepolymers having amine groups and the multifunctional crosslinker. 
     
     
         17 . The environmentally responsive hydrogel of  claim 1 , wherein the environmentally responsive hydrogel is introduced through a microcatheter filled with saline at physiological pH 
     
     
         18 . The environmentally responsive hydrogel of  claim 1 , wherein the environmentally responsive hydrogel is introduced through a microcatheter filled with blood.