TY  - JOUR
A1  - Gäbert, Chris
A1  - Rosenstingl, Tobias
A1  - Linsler, Dominic
A1  - Dienwiebel, Martin
A1  - Reinicke, Stefan
T1  - Programming viscosity in silicone oils
BT  - reversible tuning of rheological properties in 9-anthracene ester-terminated polydimethylsiloxanes
JF  - ACS applied polymer materials
N2  - Programmable oils feature tunable viscosity and therefore possess potential for technical improvements and innovative solutions in many lubricated applications. Herein, we describe the first assessment of the variability of rheological properties of light-programmable 9-anthracene ester-terminated polydimethylsiloxanes (PDMS-As), including implications that arise with UV-light as an external trigger. We applied a modified rheometer setup that enables the monitoring of dynamic moduli during exposure to UV-light. The reversible dimerization of anthracene esters is used to either link PDMS chains by UV-A radiation (365 nm) or cleave chains by UV-C radiation (254 nm) or at elevated temperatures (>130 degrees C). Thermal cleavage fully restores the initial material properties, while the photochemical cleavage of dimers occurs only to a limited extent. Prolonged UV radiation causes material damage and in turn reduces the range of programmable rheological properties. The incomplete cleavage contributes to a gradual buildup of viscosity over a course of several switching cycles, which we suggest to result from chain length-dependent reaction kinetics. Material property gradients induced during radiation due to attenuation of the light beam upon its passing through the oil layer have to be considered, emphasizing the need for proper mixing protocols during the programming step. The material in focus shows integrated photorheology and is suggested to improve the performance of silicone oils in friction systems.
KW  - polysiloxane
KW  - lubricant
KW  - light-programmable viscosity
KW  - anthracene
KW  - dimerization
KW  - reversible chain extension
Y1  - 2020
U6  - https://doi.org/10.1021/acsapm.0c00794
SN  - 2637-6105
VL  - 2
IS  - 12
SP  - 5460
EP  - 5468
PB  - ACS Publications
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Liebig, Ferenc
A1  - Sarhan, Radwan Mohamed
A1  - Sander, Mathias
A1  - Koopman, Wouter-Willem Adriaan
A1  - Schuetz, Roman
A1  - Bargheer, Matias
A1  - Koetz, Joachim
T1  - Deposition of Gold Nanotriangles in Large Scale Close-Packed Monolayers for X-ray-Based Temperature Calibration and SERS Monitoring of Plasmon-Driven Catalytic Reactions
JF  - ACS applied materials & interfaces
KW  - gold nanotriangles
KW  - monolayer formation
KW  - SERS
KW  - dimerization
KW  - heat measurement
Y1  - 2017
U6  - https://doi.org/10.1021/acsami.7b07231
SN  - 1944-8244
VL  - 9
SP  - 20247
EP  - 20253
PB  - American Chemical Society
CY  - Washington
ER  -