Table 1.

Composition of samples (in at.%) derived from X-ray photoelectron spectroscopy (XPS) analysis. The traces of sodium, chlorine, and phosphorus were detected but were not taken into account.

Sample Name	[C], at.%	[O], at.%	[N], at.%
PCL-ref	73.9	26.1	0.0
PCL-APO	75.8	22.0	2.2
PCL-ANG	78.0	22.0	0.0
PCL-COOH	72.3	27.5	0.3
PCL-COOH-APO	72.6	24.5	2.9
PCL-COOH-ANG	72.4	26.5	1.1
PCL-COOH-FN	71.3	23.1	5.6