nature works u2122 a division of cargill dow llc tlf 6267 polyglycolic acid u201c pga u201d from dupont specialty chemicals polycaprolactams and mixtures of pla and pga solid acids such as sulfamic acid trichloroacetic acid and citric acid held together with a wax or other suitable binder material polyethylene homopolymers and paraffin waxes polyalkylene oxides such as polyethylene oxides and polyalkylene glycols such as polyethylene glycols these polymers may be preferred in water based drilling fluids because they are slowly soluble in water in one specific embodiment having an encapsulating dissolvable material the expandable material is one or more chemical components that undergo a chemical reaction when expandable seal inserts 60 62 are contacted with the fluid being pumped through bore 44 and port 46 of the downhole tool for example the expandable material may be a combination of solid particles of magnesium oxide and monopotassium phosphate encapsulated by one or more of the above referenced encapsulating dissolvable materials after the dissolution of the encapsulating dissolvable material the chemical components of the expandable material react in the presence of the fluid e g water or hydraulic fluid causing the chemical components to form a gel phase and ultimately a crystallized solid ceramic material magnesium potassium phosphate hexahydrate which is a chemically bonded ceramic in such embodiments the.