• Top library match: Polyacrylamide #38676

• The 1406 cm⁻¹ band is attributed to carbonate in literature [7], an assignment incompatible with the organic polymer chemistry observed; the band is better explained by carboxylate.
• The library match confidence is low (15%), and the proposed polyacrylamide library candidate does not fully account for the observed ester-like carbonyl and hydroxyl bands without invoking significant modification.
• The presence of amide functionality remains ambiguous because the amide I region overlaps with water bending at 1639 cm⁻¹ and no amide II band is clearly observed.
• Aromatic bands expected from the library direction are not distinct in the spectrum, leaving the aromatic content uncertain.
• The exact composition (e.g., ratio of amide to carboxyl, degree of esterification) cannot be determined from the present data alone.

Recommended next steps: Acquisition of a spectrum after drying or under controlled humidity would resolve water interference and possibly reveal an amide I band. Recording a derivative or difference spectrum could help detect amide II near 1540–1550 cm⁻¹ if present. Complementary techniques such as elemental analysis, nuclear magnetic resonance, or saponification followed by ion chromatography are recommended to confirm the carboxyl and ester content and to verify the absence of aromatic rings.