TY  - JOUR
A1  - Machatschek, Rainhard Gabriel
A1  - Heuchel, Matthias
A1  - Lendlein, Andreas
T1  - Thin-layer studies on surface functionalization of polyetherimide
BT  - hydrolysis versus amidation
JF  - Journal of materials research : JMR / Materials Research Society
N2  - Among the high-performance and engineering polymers, polyimides and the closely related polyetherimide (PEI) stand out by their capability to react with nucleophiles under relatively mild conditions. By targeting the phthalimide groups in the chain backbone, post-functionalization offers a pathway to adjust surface properties such as hydrophilicity, solvent resistance, and porosity. Here, we use ultrathin PEI films on a Langmuir trough as a model system to investigate the surface functionalization with ethylene diamine and tetrakis(4-aminophenyl)porphyrin as multivalent nucleophiles. By means of AFM, Raman spectroscopy, and interfacial rheology, we show that hydrolysis enhances the chemical and mechanical stability of ultrathin films and allows for the formation of EDC/NHS-activated esters. Direct amidation of PEI was achieved in the presence of a Lewis acid catalyst, resulting in free amine groups rather than cross-linking. When comparing amidation with hydrolysis, we find a greater influence of the latter on material properties.
KW  - Membrane
KW  - Nanostructure
KW  - Polymer
KW  - Raman spectroscopy
KW  - Scanning probe microscopy (SPM)
KW  - Surface reaction
KW  - Thin film
Y1  - 2021
U6  - https://doi.org/10.1557/s43578-021-00339-7
SN  - 0884-2914
SN  - 2044-5326
VL  - 37
IS  - 1
SP  - 67
EP  - 76
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Izraylit, Victor
A1  - Liu, Yue
A1  - Tarazona, Natalia A.
A1  - Machatschek, Rainhard Gabriel
A1  - Lendlein, Andreas
T1  - Crystallization and degradation behaviour of multiblock copolyester blends in Langmuir monolayers
JF  - MRS communications / a publication of the Materials Research Society
N2  - Supporting the wound healing of soft tissues requires fixation devices becoming more elastic while degrading. To address this unmet need, we designed a blend of degradable multiblock copolymers, which is cross-linked by PLA stereocomplexation combining two soft segments differing substantially in their hydrolytic degradation rate. The degradation path and concomitant structural changes are predicted by Langmuir monolayer technique. The fast hydrolysis of one soft segment leads to a decrease of the total polymer mass at constant physical cross-linking density. The corresponding increase of the average spacing between the network nodes suggests the targeted increase of the blend's flexibility.
KW  - Degradable
KW  - In situ
KW  - Microstructure
KW  - Thin film
Y1  - 2021
U6  - https://doi.org/10.1557/s43579-021-00107-y
SN  - 2159-6859
SN  - 2159-6867
VL  - 11
IS  - 6
SP  - 850
EP  - 855
PB  - Springer
CY  - Berlin
ER  -