Superabsorbent Polymers Based on Citric Acid Having Enhanced Biodegradability and Water Absorptivity

A superabsorbent polymer which:

• has one or more glass transition temperatures, determined by Dynamic Mechanical Thermal Analysis, and each one of the one or more glass transition temperatures is in the range of from and including 10 up to and including 140° C.,
• has a decomposition temperature determined by Thermogravimetric Analysis, of at least 190 and at most 350° C.,
• has a rubbery plateau storage modulus at 160° C. (abbreviated as G′p), determined by Dynamic Mechanical Thermal Analysis, of at least 30 kPa and at most 5000 kPa, and
• comprises in an amount of at least 80 and at most 100 mol % on superabsorbent polymer, reacted residues of a citric component and a multi-functional component,
• wherein
• the citric component is present in an amount of at least 40 and at most 75 mol % on superabsorbent polymer,
• wherein
• the citric component consists of a citrate component and a citric acid component,
• and wherein
• the citrate component is selected from the group consisting of mono-sodium citrate, mono-potassium citrate, mono-silver citrate, mono-lithium citrate, di-sodium citrate, di-potassium citrate, di-silver citrate, di-lithium citrate and mixtures thereof, and is present in an amount of at least 15 and at most 50 mol % on superabsorbent polymer,
• and wherein
• the citric acid component is selected from the group consisting of citric acid, citric acid anhydride, citric acid esters, and mixtures thereof, and is present in an amount of at least 15 and at most 50 mol % on superabsorbent polymer,
• and wherein
• the multi-functional component is present in an amount of at least 25, and at most 60 mol % on superabsorbent polymer,
• and wherein
• the multi-functional component consists of a polyhydroxy component and optionally of a component A which component A consists of one or both of a dihydroxy alcohol component and an amino-hydroxy component,
• and wherein
• the polyhydroxy component is selected from the group consisting of C3-C10 saturated aliphatic trihydroxy alcohols, C5-C14 saturated aliphatic tetrahydroxy alcohols, C4-C24 sugar alcohols, C3-C10 saturated aliphatic trihydroxy ethers, C4-C12 saturated aliphatic tetrahydroxy ethers, C5-C14 saturated aliphatic pentahydroxy ethers, C6-C16 saturated aliphatic hexahydroxy ethers, and mixtures thereof, and wherein
• the polyhydroxy component is present in an amount of at least 25 and at most 60 mol % on superabsorbent polymer,
• and wherein
• the dihydroxy alcohol component is selected from the group consisting of C2-C12 saturated aliphatic dihydroxy alcohols and mixture thereof;
• and wherein
• the amino-hydroxy component is selected from the group consisting of C2-C14 saturated aliphatic secondary amines comprising two hydroxyl groups, C3-C20 saturated aliphatic tertiary amines comprising three hydroxyl groups, and mixtures thereof.