Unexpected strong paramagnetism of hydrogels containing carbon–oxygen double bonds induced by calcium cations

Key Points

• Paramagnetism significantly increases in hydrogels with calcium cations and carbon-oxygen double bonds.
• Key evidence shows a substantial increase in magnetic susceptibility with the addition of calcium cations.
• Observational analysis indicates strong ionic interactions between calcium and hydroxyl groups in the hydrogels.
• This finding highlights the need for further studies on the applications of these hydrogels in material science.