Elastic moduli for a diblock copoly(2-oxazoline) library obtained by hight-hroughput screening

Kranenburg, Johannes M.; Tweedie, Catherine A.; Hoogenboom, Richard; Wiesbrock, Frank; Thijs, Hanneke M. L.; Hendriks, Chris E.; Vliet, Krystyn J. Van; Schubert, Ulrich S.

Abstract:

Using depth-sensing indentation, the elastic modulus E of a diblock copoly(2-oxazoline) library was investigated in order to determine structure–property relationships. The adopted experimental procedure, dropcasting of the copolymer materials and determining the elastic modulus by depth-sensing indentation, was compatible with high-throughput experimentation. The elastic modulus of the investigated materials depended strongly on the side-group. Materials containing poly(nonyloxazoline) exhibited a lower modulus than materials without any poly(nonyloxazoline) block as poly(nonyloxazoline) was at room temperature above its glasstransition temperature Tg, while the other homopolymers in this study were glassy at room temperature. The elastic modulus also depended on the relative humidity (RH) of the testing environment; the stiffness of ethyloxazoline and methyloxazoline decreased significantly due to water absorption from the air. At lower RH, hydrogen bonding or polar interactions among the polymer chains resulted in a surprisingly high modulus for the poly(methyloxazoline). In addition, as anticipated, the elastic moduli of AB diblock copolymers were bounded by those of the A and B homopolymers, both at high and at low RH. The presented results indicate how, and to what extent, for these materials the E (and the change in E) at a given (change in) humidity can be adjusted by tailoring the composition.

Year:

2007

Type of Publication:

Article

Journal:

Journal of Materials Chemistry

Volume:

17

Pages:

2713 - 2713