Optical Materials Express, 11, 371-384 (2022)
Two-photon laser polymerization (TPP) is a state-of-the-art technology that allows for the submicron-resolution printing of freeform 3D objects to be harnessed in various applications, including physics, biology, medicine, and materials science. The TPP is based on using photosensitive polymeric materials that impose restrictions on the minimum feature size and limit the functionality of printed structures within the capabilities of polymers. One of the promising yet insufficiently studied methods for overcoming these limitations is pyrolysis–high-temperature annealing of polymer objects in an inert atmosphere. It may allow both to decrease the size of the objects and modify their chemical composition. Here, we compare the effect of pyrolysis on solid objects being tens of micrometers in size printed by TPP from three commercially available photoresists: IP-Dip, OrmoComp, and SZ2080. For the annealing temperatures of 450°C and 690°C in an argon atmosphere, we assessed the changes in size, chemical composition, and adhesion to the silicon wafer substrate. Our data may be promising for developing pyrolysis as a standard post-processing method for structures created via TPP technology.
IOP Science "Nanotechnology", 32, 095206 (2021)
We demonstrate that single-walled carbon nanotube (SWCNT) membranes can be successfully utilized as nanometer-thick substrates for enhanced visualization and facilitated study of individual nanoparticles. As model objects, we transfer optically resonant 200 nm silicon nanoparticles onto pristine and ethanol-densified SWCNT membranes by the femtosecond laser printing method. We image nanoparticles by scanning electron and bright-field optical microscopy, and characterize by linear and Raman scattering spectroscopy. The use of a pristine SWCNT membrane allows to achieve an order-of-magnitude enhancement of the optical contrast of the nanoparticle bright field image over the results shown in the case of the glass substrate use. The observed optical contrast enhancement is in agreement with the spectrophotometric measurements showing an extremely low specular reflectance of the pristine membrane (≤0.1%). Owing to the high transparency, negligibly small reflectance and thickness, SWCNT membranes offer a variety of perspective applications in nanophotonics, bioimaging and synchrotron radiation studies.
PRX Quantum, 2, 010307 (2021)
Applied Surface Science, 535, 146345 (2020)
Dendrimers are unique macromolecules composed of branched monomers that are characterized by monodispersity, biocompatibility, and multivalent surfaces and are synthesized by the stepwise addition of repetitive units. Over recent years, dendrimers have been attractive materials as detecting agents, targeting components, imaging agents, or pharmaceutically active compounds. This study demonstrates the possibility of the formation and transfer of thin sulfonimide dendrimer films of different generations to solid surfaces using the Langmuir-Blodgett technique. The surface of sulfonimide dendrimers was functionalized with naphthalene end groups (from 4 to 64 groups). The developed noncovalent and covalent films showed the expected different contact angles due to the presence of the naphthyl groups attached to the dendrimer side, which can bond intramolecularly or intermolecularly. Changing the number of naphthyl groups allows control of the hydrophobic properties of the films, providing an opportunity to create two types of films with covalent and noncovalent bonding. The difference in contact angle between the 2nd and 5th generations of dendrimers was approximately 33°. The low-cost formation of such transparent water-repellent film imparting water repellency to a substrate while maintaining its inherent properties, such as color and morphology, can protect glass and painted surfaces from excessive humidity.