three-dimensional patterning of solid microstructures through laser reduction of colloidal graphene oxide in liquid-crystalline dispersions - dupont mylar film
Graphene materials and structures have become an important part of modern electronics and photovoltaic.
However, despite many production methods, the application of graphene
Due to the high cost, lack of scalability and limitations of spatial patterns, structure-based structures are hindered.
We made three here.
Reduction of three-dimensional multi-functional Solid Microstructure of graphene oxide-soluble to-column liquid crystal graphene oxide sheets using pulse approachinfrared laser.
This reliable, scalable approach is shielding
Free, no special chemical reducing agent is required, and can be achieved under environmental conditions starting from graphene oxide sheets.
Ordered orientation of graphene oxide sheet in self
The crystal phase can achieve complex three-
Reduced-size graphene oxide structures and colloidal particles, such as trefoil knots, have a "frozen" orientation order for thin sheets.
These structures and particles are mechanically rigid, ranging in sizes from a few hundred nanometers to a few millimeters, which is the need for applications of colloidal, electronic, photon and display technologies.
The main improvement is single
The layer GO sheet used in this work is through the large-
Large-scale production, obtained as a dispersion in Deion (DI)
Water with a concentration of 2. 5u2009gu2009l (0. 25u2009wt%).
The synthesis and purification process of GO sheet are as follows: xGnP 5-3gm-graphite-nanoplatelets (
Add 200 ml of 9:1 HSO/HPO solution to 1-l Pyrex beaker.
Mix continuously using IKA Werke RW 16 mechanical mixer.
Slowly, stir 9G KMnO into the mixture, which turns into a dark green color.
Precautions were taken to avoid adding 5 wt % more than KMnO each time, and to ensure that the change in color from green to purple was completed before more antioxidants were introduced (
This is important because a solution with KMnO more than 7 wt % added to HSO can explode when heated).
Use aluminum foil to cover the mouth of the Beaker as much as possible and use a resistor to heat the reaction to 40 °c-
After 6 h, the mixture thickens from dark green to purple-pink.
At this point, an additional 9G KMnO was added and a reaction to another 6G was allowed.
When the reaction is completed, the ice of the obtained slurry is 200 ml-
5 ml of water containing 30% HO.
Bright yellow GO suspended solids obtained by a series of centrifugation and re-purification
Suspended in pure solvent.
All centrifuges are performed at 4,000 µr. p. m.
90 minutes, all over again
Suspension is carried out by shaking the centrifugal GO 4 u2009 h at 200r. p. m.
On the platform rocking bed using 200 solvent.
The product is centrifugal once as is, once in di ho, once in 30% HCl and twice in di ho.
To determine the concentration of the Final Solution, a 10-
Filter ml equal sample
Wash with 200 ml of methanol, acetone and diethyl ether in three different solvents.
The final material is vacuum dried overnight at 4 tortorr and room temperature and weighed (25u2009mg).
In addition, the water dispersion of the GO sheet is tip
The use of the Branson 250 ultrasonic generator for ultrasonic treatment of 2 Thanh at 35 w ultrasonic power (VWR Scientific)
The operating frequency is 20 khz, equipped with a micro-tip with a diameter of 4.
8mm, can achieve a single scattered sheet of smaller size.
Uniform column liquid crystal phase ()
By controlled removal of excess water from a centrifugal dispersion in a Sorvall Legend 14 centrifuge, a higher concentration of GO flakes were obtained in the dispersion (
Thermal Science)at 12,000u2009r. p. m. for 10-15u2009min.
GO's LC dispersion is sandwiched between two glass substrates.
Clean untreated glass substrates were used in laser samples
Induced reduction of GO flakes and observation of optical and nonlinear microscopy.
Use Mylar film to set the gap between substrates (DuPont Teijin)
The dispersion of GO flakes is ultrasound-in Cole-
Parmer 8891 ultrasonic bath for 5 min before assembling cells.
Prevent water evaporation during the experiment by sealing the sample with UV curing glue (
NOA 63 Norland Products Co. , Ltd. ).
To retrieve the resulting rGO microstructure for SEM imaging, a sample was removed and the GO dispersion and rGO microstructure were released together into a petri dish with DI water.
Then, after "cleaning" it in DI water, soak the rGO microstructure with some water into the tip of the transfer tube and place it on the silicon wafer ().
After the residual water evaporated, we performed SEM imaging.
Using a multimodal nonlinear optical microscope setup coupled with inverted Olympus microscope IX-, an integrated 3D laser-induced reduction and nonlinear light-emitting imaging of GO aqueous solution samples at room temperature81 (). A tunable (680-1,080u2009nm)
Titanium: sapphire oscillator (
14 Xperia fs, 80 mhz, Chameleon Ultra II, coherent)
Used as an incentive source.
The excitation beam is directed to the sample through a mirror system (DMs)
Focus into the sample using Olympus high numerical aperture (NA)
Oil target 100 ×/NA = 1. 4 (OL1).
The spatial 3D position of the excitation beam in the sample volume is controlled by a mirror scanning unit (
Average laser power from a pair of Glan polarizers and a half-control luminous imaging
The wave sheet in the sample should be less than 1 mw to prevent taking pictures
And heat damage.
The excitation of GO flakes is carried out at 8nm ()
, And non-polarized light is detected in the 400-range700u2009nm ()
H5784 with binsong photoelectric multiplier tube in reverse mode-20 (PMT1).
Mode single wave long bright-
Collect live images in forward mode with pmt2.
The polarization of excitation can be changed in half. or quarter-
The wave delay plate installed in front of the target.
The same setting is used for 3D reduction of the water GO sheet using the pulse laser beam of 8nm and the laser injection amount