Carboxymethylated-, hydroxypropylsulfonated- and quaternized xylan derivative films

• Three ion-exchanging groups were introduced into xylan in one step.
• The properties were compared with double and single substituted xylan.
• Films were prepared from the derivatives and tested.
• Roughness values of film top sides were bigger than on bottom.

Under alkaline/water conditions carboxymethyl, 2-hydroxypropylsulfonate and trimethylammonium-2-hydroxypropyl groups were introduced into xylan in one step with the goal to prepare film specimens. The materials were characterized by NMR, SEC-MALS, TG/DTG/DTA, AFM and mechanical testing. The properties of triple, double and mono-substituted materials were compared. The numerical molar masses of the specimens were from 12.3 to 17.6 kg/mol with Mw/Mn from 1.27 to 1.34. The elastic modulus values are decreasing in order: xylan (X; 7354 MPa) > carboxymethyl xylan (CX; 6090 MPa) > 2-hydroxypropylsulfonate xylan (SX; 6000 MPa) > carboxymethyl/2-hydroxypropylsulfonate xylan (CSX; 4490 MPa) > quaternized xylan (QX; 3600 MPa) > carboxymethyl/quaternary/2-hydroxypropylsulfonate xylan (CQSX; 3380 MPa) > carboxymethyl/quaternary xylan (CQX; 2805 MPa). The onset temperatures of SX (214 °C), CQSX (212 °C), QSX (211 °C) and CQX (207 °C) were higher than for X (205 °C). The roughness values of the film surfaces (3.634 – 18.667 nm) are higher on top than on the bottom of the specimen.