TY  - JOUR
A1  - Melchert, Christian
A1  - Behl, Marc
A1  - Nöchel, Ulrich
A1  - Lendlein, Andreas
T1  - Influence of Comesogens on the Thermal and Actuation Properties of 2-tert-Butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone Based Nematic Main-Chain Liquid Crystalline Elastomers
JF  - Macromolecular materials and engineering
N2  - Although the shape-changing capabilities of LCEs hold great potential for applications ranging from micropumps to artificial muscles, customization of the LCE functionality to the applications' requirements is still a challenge. It is studied whether the orientation of NMC-LCPs and NMC-LCEs based on 2-tert-butyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone can be enhanced by copolymerization with 2-methyl-1,4-bis[4-(4-pentenyloxy)benzoyl]hydroquinone or 2,6-bis[4-(4-pentenyl-oxy)-benzoyl]anthracene. An increasing content of the comonomers stabilizes the nematic phase, which enables a tailoring of T-NI for the NMC-LCP between 45 and 68 degrees C, while for the NMC-LCE T-NI ranges between 69 and 76 degrees C. In addition, NMC-LCE show an increased actuation performance.
KW  - elastomers
KW  - liquid-crystalline polymers
KW  - polysiloxanes
KW  - stimuli-sensitive polymers
KW  - thermal properties
Y1  - 2012
U6  - https://doi.org/10.1002/mame.201200238
SN  - 1438-7492
VL  - 297
IS  - 12
SP  - 1203
EP  - 1212
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Zaupa, Alessandro
A1  - Neffe, Axel T.
A1  - Pierce, Benjamin F.
A1  - Nöchel, Ulrich
A1  - Lendlein, Andreas
T1  - Influence of tyrosine-derived moieties and drying conditions on the formation of helices in gelatin
JF  - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences
N2  - The single and triple helical organization of protein chains strongly influences the mechanical properties of gelatin-based materials. A chemical method for obtaining different degrees of helical organization in gelatin is covalent functionalization, while a physical method for achieving the same goal is the variation of the drying conditions of gelatin solutions. Here we explored how the introduction of desaminotyrosine (DAT) and desaminotyrosyl tyrosine (DATT) linked to lysine residues of gelatin influenced the kinetics and thermodynamic equilibrium of the helicalization process of single and triple helices following different drying conditions. Drying at a temperature above. the helix-to-coil transition temperature of gelatin (T > T-c, called nu(short)) generally resulted in gelatins with relatively lower triple helical content (X-c,X-t = 1-2%) than lower temperature drying (T < T-c, called nu(long)) (X-c,X-t = 8-10%), where the DAT(T) functional groups generally disrupted helix formation. While different helical contents affected the thermal transition temperatures only slightly, the mechanical properties were strongly affected for swollen hydrogels (E = 4-13 kPa for samples treated by nu(long) and E = 120-700 kPa for samples treated by nu(short)). This study shows that side group functionalization and different drying conditions are viable options to control the helicalization and macroscopic properties of gelatin-based materials.
Y1  - 2011
U6  - https://doi.org/10.1021/bm101029k
SN  - 1525-7797
VL  - 12
IS  - 1
SP  - 75
EP  - 81
PB  - American Chemical Society
CY  - Washington
ER  -