antireflective coatings using organically modified silica and polyimide via solution casting method.

by:ZHENHUA     2020-04-05
Introduction to anti-reflection (AR)
The coating can improve the transmission of lighting display screens, windows, optical filters, solar cells and light detectors (1-4).
The first antireflection (AR)
In 1817, Fraunhofer discovered the coating on the glass substrate (5).
A few years later, Poisson and fenfresnel define the AR phenomenon as destructive interference between light reflected from the air --
Coating and coating
Sub-interface (6).
Therefore, the AR coating should show the refraction index between the air and the substrate.
For an ideal uniform single layer, the film thickness and refractive index can be used to quantify the anti-reflection degree using the following two equations (7), (8): [n. sub. c]= [Square root ()[n. sub. s]x [n. sub. m])](1)[d. sub. 1]= [lambda]/4[n. sub. 1](2)where [n. sub. c], [n. sub. m], [n. sub. s]
It is the refractive index of the coating, medium and substrate. Where [d. sub. 1]
Thickness of AR coating and [lambda]
The wavelength of accidental light that usually falls on the substrate in the air.
As the index of light (RI)
The material is inherent, and the atypical way to change the RI is to add air to the matrix in two or three dimensions (9-11). The [n. sub. c]
The best AR performance can be achieved by adjusting the hole degree in the film.
There are a variety of other techniques to make films with adjustable refractive index such as chemical etching, vacuum deposition, and sol--gel method.
One way is to rough the surface by chemical etching to produce a sub-visible-wave-
Scalp length (12-15).
The main disadvantages are the time-consuming and use of harmful etchant such as HF and [H. sub. 2]Si[F. sub. 4]. Si[F. sub. 4].
As an alternative to chemical corrosion, chemical deposition is also an important technology for the preparation of AR Films (16-19).
Surface roughness and particles can be formed on the surface of the film by sputtering (16-18)
Physical Vapor Deposition (19), and plasma-
Enhanced chemical vapor deposition (20).
AR coating can also be prepared by aself-in multi-layer process
Assembly method (21-23).
Both the spin and dip processes are used, sometimes in combination. A post-
In order to produce roughness on the surface of the coating, treatment such as sintering and sintering is usually required. Li et al. (21)produced self-
Clean permeable membrane frommesoporous silica nanoparticles pass through a layerby-layer (LBL)
It is calledized. Zhang (22)
Reported self-made
Deposited Si [clean AR Coating0. sub. 2]single-
Layered particle coating on polyelectrolyte
The modified glass substrate is attracted by static electricity, then another layer of nanoparticles is deposited by electrostatic attraction, and then roasted at [50 °c]degrees]
C remove polymer. Rouse (23)
By sequential adsorption of cation polyelectrolyte and silica soil, AR coatings with controllable thickness and refractive index were prepared. Sol--
AR coating is also produced using gel method. Yoldas(24)
Patented and quarterly porous AR layer
Obtain the wavelength-thick light on the glass substrate from the transparent sol of aluminum alkoxidea by dipping coating process, and then heat to 300 [degrees]C-500[degrees]
C converts the porous layer into a metal oxide. Nostell et al. (2)
Preparation of AR Film on glass by dip
From sol--
A gel of 50 nm monodispersed silica particles is added to the mixture of ethanol and water and then roasted.
The sun transmission ratio of 99. Achieved 2%. Vicente (25)reported sol--
Gel polymer Ti [O. sub. 2]
The AR film is coated by dipping and then sintering in air.
The film thickness and refractive index can be customized by changing the withdrawal rate of the dipping coating process and the ratio of Titanium four oxygen compounds (TbuTi)to ethanol. Faustini (26)
Developed an elf.
Cleaning and anti-fog coating using two methods
One-Step stewing process.
The AR layer consists of a mixed methyl group.
Functional nano-pore Si [0. sub. 2]
From sol.
The second level is self. cleaning Ti[O. sub. 2]
Hard layer obtained from adip coating roasting process.
In this study, the film was prepared from soluble pi and organic modified silica gel using a streamer.
Pi provides optical transparency and mechanical properties in the visible range.
Modification of silica gel (
Used to drive the gel into the air. film interface.
The pi and colloid prepared were characterized by ir and NMR.
The film was characterized using SEM and UV--
Experimental material four ethyl positive Silicon (
Reagent, premium level, 98%)
, Hexamethyltricyclosiloxane (D3, 98%), n-
Butyllithium in Berlin (n-BuLi,2. 5 M)
Nitrogen chloride (98%), anhydrous N-methyl-pyrrolidione(NMP, 99. 5%)
, No ding erone (DMAc, 99. 8%)
Huanpentone (99%)
Water free toluene (99. 8%)
B thin (
Reagent grade 98%),platinum(0)-1,3-divinyl-1,1,3,3-tetra-
Methyl disilicone (
Karstedt\' scatalyst)in xylene (2% Pt)
Bought from Sigma. Aldrich. Anhydroustetra-furan (99%)
It was obtained from Acros. 2,2\'-Bis[4-(3,4-
2) phenol oxygen)phenyl]
Propane Malay (BPADA)
It is obtained from the polymerization science, and it is re-crystallized from the mixture of toluene and ethylene. The 4,4\'-oxydia-niline (ODA, 97%)
Purchased from Aldrich and purified according to US patent [j]20],(Heptaecafluoro-1,1,2,2-()
Three ethoxy silane andvinyltrimethoxysilane (VTMS)
It was obtained from Gelest.
Ammonia hydroxide (28-30% wt)
From J. T. Baker.
Get ethanol from pharmaceutical companiesaaper (
Proof of absolute, waterless, ACS/USPgrade 200).
All reagents are used as received unless otherwise stated.
Infrared spectrum (
Hot electronic Com)
The spectrum was taken on Nicollet 380 (
Preparation of samples, ultrasonic oxidation of silica in acetone, dripping on the surface of KBr particles and drying. Resolution: 4 [cm. sup. -1].
Number of scans: 32, [. sup. 1]
H nmr spectra were obtained from Mercury
300 spectrometer (Varian)
In solid methanol or methane-state [. sup. 13]C NMR and [. sup. 29]
Si NMR was recorded on AGeminin-
400 spectrometer (Varian)
At room temperature
The water system is used to predict and analyze HR4, HT2, HR1 and hr0.
5 Styragel and 500A Ultrastyragel columns are connected in series.
Four fluorine ether was transported as mobile phase at a rate of 1. 0 mL/min.
Transmission electron microscope (
TEM, Movement for Justice and Equality)
Used to observe the morphology and size of silica particles (
Preparation of samples, dilute solution of ethanol, drop on copper mesh surface coated with carbon film). UV-
HP Agilent 8 UV/vis spectrometer in 200-
1000 nm, the coating on pet is stripped (PET)substrate.
Field emission scanning electron microscope (SEM, jeol jsm-7401f)
Used to study the morphology and distribution of silica particles in reduction reactionair interface.
Atomic force microscope (
Nano microscope III)
The morphology of some coatings was also studied by tapping mode.
Synthesis of fluorine silicon particles: fluorine Silicon-5,Fluorosilica-
10, fluorine Silicon-30.
Ethanol without water (50 mL)
And ammonia hydroxide (3. 7 mL)
Was stirred for half an hour on [65]degrees]C in the three-
Neck bottle with condenser. Then,TEOS (1. 5 mL, 1. 41 g, 0. 0067 mol, 0. 14 mol/L)
Add in the mixture and stir for 24 hours at 65 [degrees]C.
After that, the three fluorine-Silicon colloidal compounds (Fluorosilica-5, fluorine Silicon-
10, fluorine Silicon-30)
By changing the Moore ratio (hepadecafluoro-1,1,2,2-()
Silicon and TEOS. Fluorosilica-
5 was prepared with a molar ratio of 1: 51,1,2,2-()
Silicon three oxygen (1. 64 g, 2. 35 mmol)toTEOS.
Again, silicon fluoride-
10 and silicon fluoride-
30 prepared at 1: 10 and 1: 30 moles ratio1,1,2,2-()-
Silicon three oxygen (0. 82 g, 0. 67mmol; 0. 273 g, 0. 225 mmol), respectively.
All three reactions were carried out at 65 [degrees]
C 10 h more, then in 80 [degrees]C for1 h.
The nanoparticles were characterized by DLS, showing an average diameter of 42 nm ([sigma]= 3. 8 nm).
The characteristic of silica gel particles is 【. sup. 1]H NMR, solid-state [. sup. 13]C NMR, solid-state [. sup. 29]
Infrared spectrum: NMR (300 MHZ, Me0D)[sigma]3. 85(-Si-C[H. sub. 2]C[[H. bar]. sub. 2][C. sub. 8][F. sub. 17]), 1. 04(-Si-C[[H. bar]. sub. 2]C[H. sub. 2][C. sub. 8][F. sub. 17]), 3. 49(OC[[H. bar]sub. 2]C[H. sub. 3]), 1. 18 (OC[H. sub. 2]C[[bar. H]. sub. 3])ppm; [. sup. 13]C NMR (300 MHZ)[sigma]112. 3 ([C. bar][F. sub. 3]), 118. 5([bar. C][F. sub. 2]), 25. 1 (-[bar. C][H. sub. 2]), 3. 3 (Si-[bar. C][H. sub. 2]),60. 5(O[bar. C][H. sub. 2]C[H. sub. 3]), 17. 3(OC[H. sub. 2][bar. C][H. sub. 3])ppm; [. sup. 29]Si NMR (400 MHZ)[sigma]= -110 (Si[(OSi). sub. 4],[Q. sup. 4]), -100 (Si[(OSi). sub. 3]0H, [Q. sup. 3]), -65 ([T. sup. 2]), -73([T. sup. 3])ppm. IR: 1030(Si-O-Si), 1053-1250(Si-C, C-F)[cm. sup. -1].
Synthesis of vinyl silica particles.
Ethanol without water (50 mL)
Ammonium hydrogen (3. 7 mL)
Was stirred for 30 minutes on [65]degrees]C in a three-
Neck bottle with condenser. Then, TEOS(1. 5 mL, 1. 41 g, 0. 14 mol/L)
Add in the mixture and stir for 24 hours at 65 [degrees]C.
After that, vinyl three-oxygen Silicon (0.
8g, Moore ratio: VTMS: TEOS = 1:10)
Add in the flask and the reaction lasts for 10 hours.
Reaction temperature increased to 80 [degrees]
C completed the response for 1 h.
The nanoparticles are characterized by dynamic light scattering with a diameter of 63 nm ([. sup. 29]Si NMR (400 MHZ)[sigma]-110(Si[(OSi). sub. 4], [Q. sup. 4]), -100 (Si[(OSi). sub. 3]0H, [Q. sup. 3]), -65([T. sup. 2]), -73 ([T. sup. 3])ppm. IR: 3300(-0H), 1100 (Si-O-Si), 1200(Si-C), 1630(-C=C-), 2830(-C[H. sub. 2]-), 2950(-C[H. sub. 3])[cm. sup. -1].
Synthesis of silicone rubber with single hydrogen sealing end: high molecular weight, h silicone rubber;
Medium molecular weight, MPDMS;
Low molecular weight, l principle.
N-n-butyllithium (10 mL, 25.
0, note: very dangerous, must be used carefully)
There are good and bad, 250 ml tricolor in monthly mLanhydrous
Neck bottle in ar atmosphere.
After 30 minutes of stirringdegrees]
C, hexamethylcyclotríloxane (D3, 14 g, 62. 5 mmol)
Dissolve in a waterless THF (40 mL)
Added to the flask.
Stir the reaction mixture at room temperature for 4 hours.
Then, Silicon dichloride (5. 5 mL, 50 mmol)
Add to terminate the polymerization and remove the unreacted reactants and solvents at a vacuum of 150 [degrees]
C: 3 hours, 12 hours2 g of low-
Single hydrogen end-based silicone rubber with molecular weight (LPDMS)
A colorless liquid of 72%.
The average degree of polymerization of L silicone rubber section is 7. 5.
Changed the amount of D3 for MPDMS (27. 8 g, 125 mmol)and HPDMS(55. 6 g, 250 mmol)
The average degree of polymerization is 15 and 30, respectively.
The amount of other reactants is the same as the program for lpdm, which is keptconstant.
78% yield of MPDMS and hpdm affordeda (23. 9 g)and 74% (43. 2 g), respectively.
The characteristic of the product is [. sup. 1]H NMR, [. sup. 13]
As shown in Table 1, c nmr, IR and molecular weight and distribution were characterized by Gel chromatography. [. sup. 1]H NMR (300 MHZ, CD[Cl. sub. 3])[sigma]4. 8 (Si-[H. bar]),0-0. 21 (Si-C[[H. bar]. sub. 3]), 0. 58 (Si-[C. bar][H. sub. 2]), 1. 24(-[C. sub. 2][[H. bar]. sub. 4]), 0. 92 (-C[[H. bar]. sub. 3])ppm; [. sup. 13]CNMR (300 MHZ, CD[C1. sub. 3])[sigma]0-1. 28 (
Carbon in silicon units),1. 78 (-SiH([C. bar][H. sub. 3])2),14. 2 (Si-[C. bar][H. sub. 2]C[H. sub. 2]C[H. sub. 2]C[H. sub. 3]), 18. 0 (-[bar. C][H. sub. 3]), 25. 7(Si-C[H. sub. 2][bar. C][H. sub. 2]C[H. sub. 2]C[H. sub. 3]), 26. 6(Si-C[H. sub. 2]C[H. sub. 2][C. bar][H. sub. 2]C[H. sub. 3])ppm. IR: 2160(Si-H), 1090, 1110 (siloxane unit), 1020 (Si--O--Si)--1266 (Si-C), 2862(-C[H. sub. 2]-), 2963 (--C[H. sub. 3])[cm. sup. -1].
Synthesis of silicone rubber grafted silica particles.
Vinyl silica particles (0. 3 g)
Dispersed in acetone (30 mL)
Ultrasound for 20 minutes at the output of 3.
5 and charge two-
Flask and N-acid (30 mL)
Principle of single hydrogen root l containing end (1 g, [bar. M][. sup. 29]Si NMR: (400 MHZ)[sigma]= 22 (
Carbon on a silicon sheet), -110(Si[(OSi). sub. 4], [Q. sup. 4]), -100 (Si[(OSi). sub. 3]0H, [Q. sup. 3]), -65([T. sup. 2]]), -73 ([T. sup. 3])ppm.
IR: 1090, 1110 (siloxane unit). 1020(Si-O-Si)-1266 (Si-C), 2862 (--C[H. sub. 2]-), 2963 (-C[H. sub. 3])[cm. sup. -1].
Synthesis of soluble pi.
Three dry flames.
Equipped with a mechanical mixer, a nitrogen Inlet and an aDean-
Stark trap with condenser, 4,4 \'-ODA (1. 0022 g, 5 mmol)
Dissolve in NMP (18 g).
For this homogeneous solution, BPADA (2. 6035 g,5 mmol)
Add slowly.
Water free toluene (4 g)
When the solvent is added to the boiling water produced during the reaction process. Toluene (3 mL)
Also used to fill the reverse Dean-
Stark traps that maintain a constant solvent volume in the flask.
In the solution of 180 [, the mixture of reactants is heat simulateddegrees]C for 6 h.
After cooling the product, pour it into 1l ethanol to precipitate, and then filter and dry in a vacuum oven of 120 [degrees]
C made 2 overnight.
74 g products with output of 80%.
Pi was characterized by Gel chromatography [. sup. 1]HNMR, [. sup. 13]Nuclear magnetic resonance and infrared spectroscopy. The Ain(
Average molecular weight of numbers),[bar. M]w (
Average molecular weight), and PDI (
Multi-dispersion index)
17,000g/mol, 34,000g/mol and 2 respectively. 0, respectively. [. sup. 1]HNMR: (300 MHZ, DMSO)[sigma]= 1. 71 (-C[H. sub. 3]), 7. 13, 7. 21, 7. 37,7. 47, 7. 95 (Aromatic protons)ppm; [. sup. 13]C NMR: (300 MHZ, DMSO)[sigma]= 129. 6, 129, 120. 2(Aromatic carbon), 28. 1 (-[C. bar][H. sub. 3])ppm. IR: 1780 (C=0), 1720 (C=0), 1370 (C-N)[cm. sup. -1].
Film Casting solution casting on pro-
Use the double doctor blade to cast precision tape casting equipment. The polyimide (PI)
Solution inNMP (7. 5% wt)
Used to make the first layer on the PET carrier.
Table 2 lists the temperature of a modified silica/PI solution as an AR coating formulation.
The total weight of each preparation is 3G and all concentrations are based on the weight percentage.
In a typical process, the pi solution in the NMP (7. 5 wt%)
With a 12 \"doctor blade (
The gap distance is set to 0. 007 in,145 pm)
On a PET substrate moving 10 cm/min.
After the film is dried, cast an AR layer on the pre-dried pi film with a clearance distance of 0. 001\" (
Minimum available time: 25 points)
At a speed of 10 cm/min
Then dry the wet film at room temperature 2-
The coating is then stripped from the pet substrate and characterized by evaporation solvent for 3 h.
Results The purpose of this study was to prepare AR coatings using a solution pouring process.
Pi was selected because of its solubility in the casting solvent and its transparency in visible lighting.
A silica gel grafted with silicone or fluoride group was added to the pi to provide AR effect.
This article is divided into two parts, one is the comprehensive part (
Pi and silica gel)
Film Evaluation Section (
AR and film surface).
Pi was prepared by solution imiation in NMP (27), (28)
From BPADA and ODA as shown in Scheme 1.
The IR shows imidizedcarbonyls with undetectable polyamide acid.
The NMR confirmed IRresults and was consistent with the previously reported spectra (27),(28).
Silicone rubber and fluorine-based are tied to silicon anarticle to reduce the surface area of silica particles, thus promoting the migration of silica particles to air
Coating interface during coating drying (29).
In order to change the surface energy of the modified silica nanoparticles, the content of fluorine-substituted hydrocarbons has changed.
The size of the modified silica particles should be small enough to reduce the loss of light due to scattering and other losses (30)
Therefore, the diameter of silica particles prepared in this paper is about 50 nm.
The synthesis of fluorine-silica particles prepared three fluorine-silica gels by changing the mixing agent, as shown in Scheme 2 below.
Adjust the molar ratio of positive silicate to intermediate to 30: 1, 10: 1 and 5: 1 to prepare the corresponding fluorine Silicon-
30, fluorine Silicon-
10, fluorine Silicon-5.
Silicon fluoride-
10 and silicon fluoride-
30 well dispersed while fluorine Silicon-
5 cannot be dispersed in any solvent system (
Any of).
So only fluorine Silicon-
10 and silicon fluoride-30 were used.
TEM image of silica
Figure 10 shows. 1.
The average diameter of quartz is about 42 nm ([sigma]= 3. 8 nm)
Obtained from DLS and very close to the results obtained from TEM.
The particle surface of fluorine silicon is rough, which can be explained by the solidification relationship of Smoluchowski (31)
Among them, during the growth of primary particles, the aggregation integrates larger coacervate, resulting in large particles. The [. sup. 1]H NMR, solid-state [. sup. 13]C and solid-state (29)
The SiNMR of fluorine Silicon shows the distribution of each resonance in figure 12a-C, respectively.
Proton resonance [delta]1. 04 ppm and 3.
49ppm attributed--Si--C[H. sub. 2]C[[H. bar]. sub. 2][C. sub. 8][F. sub. 17]and--Si--C[H. sub. 2]C[[H. bar]. sub. 2][C. sub. 8][F. sub. 17], respectively.
Resonance in [delta]3. 85 and 1.
18 ppm assigned to toOC [[H. bar]. sub. 2]C[H. sub. 3]and OC[H. sub. 2]C[[H. bar]. sub. 3]
Belonging to tounhydrozed TEOS (see Fig. 2a).
Chemical transformation [delta]112. 3 ppmand 118.
5 ppm corresponding 【C. bar][F. sub. 3]and [C. bar][F. sub. 2]
Agent from coupling
Chemical transformation [delta]25. 1 ppm and 3.
3 ppm can be assigned to the other two MEPs next [C. bar][F. sub. 2]
In the coupling agent.
Although the two small resonance in [delta]60. 5ppm and 17.
3 ppm attributed to unhydrolysis [bar. C][H. sub. 2]C[H. sub. 3]and OC[H. sub. 2][C. bar][H. sub. 3]
The coupling agent was obtained from ethyl silicate.
Resonance (29)SiNMR at 6--110 ppm and--
100 ppm corresponding to theSi [(OSi). sub. 4],([Q. sup. 4])and Si[(OSi). sub. 3]0H ([Q. sup. 3])
Environment in colloidal silica (32), (33).
Other resonance from [delta]--63 ppm to--
73 ppm is relative to the Si atom in the coupling agent.
All evidence from NMR, solid 13 c nmr and solid [. sup. 29]
Si NMR proves the formation of fluorine Silicon10.
Vinyl silica particles vinyl silica nanoparticles were prepared by Stober method (34-36)
As shown in Scheme 3.
The average diameter of vinyl silicon products is about 63 nm ([sigma]= 1. 6 nm)
From DLS, this is consistent with the TEM shown in the following figure3.
As observed in the TEMimage and DLS data, the distribution of silica particles is very narrow. Solid state [. sup. 13]
C nmr shows that there are two resonances in [delta]131 ppmand [delta]
138 ppm attributed to vinyl group (--CH=C[H. sub. 2]--)
OfVTMS and solids-state [. sup. 29]Si-
NMR reveals the resonance [delta]--110 ppm and [delta]--
100 ppm corresponding to theSi [(OSi). sub. 4]([Q. sup. 4])and Si[(OSi). sub. 3]0H ([Q. sup. 3])
Environment in colloidal silica (32), (33).
Both carbon and silicon NMR confirm the formation of vinyl
Contains silicone.
Synthesis of silicone rubber grafted silica particles Silicon hydrogen addition of three single hydrogenation vinyl modified silica particles with different molecular weights-
Silicone rubber with tension was prepared with Karstedt catalyst (37-39).
A typical synthesis process of silicon-based hydrogenation (40)
As shown in Scheme 4.
Dme for the determination of three single hydrogen (
For raw materials, through environmental protection-
Open Response to D3
Proton nuclear magnetic resonance of [j]delta]4.
8 ppdemand infrared stretch band, located at 2160 [1 [cm. sup. -1]
Is a feature of si-H and the [. sup. 13]
Nuclear magnetic resonance [delta]0-0.
21 ppm corresponds to the carbon attached to the silicon sheet.
Proton, carbon NMR and IRconfirmed all confirm the successful synthesis of silicone rubber with a single hydrogen-terminated root.
Through the silicon hydrogen addition reaction catalytic by Karstedt catalyst, the silicone rubber based on the single hydrogen end is grafted onto the silica particles (41)
As shown in Scheme 5. Both solid-state [. sup. 13]C NMR and [. sup. 29]
SiNMR provided evidence that silicone rubber fragments were grafted on silicone.
Appearance of solid-state [. sup. 29]
Si NMR resonance [delta]-
22 ppm and loss--CH=C[H. sub. 2]--resonance at [delta]131 ppm and [delta]
138 ppm is consistent with the silicone rubber that exists on the surface of the particles.
Coating casting and coating formation preparation of AR coating by solution casting process4.
In this process, pi and organic modified silica are mixed in common solvents through a doctor\'s blade and pre-dried pi films are poured on the moving PET carrier.
Organic modified silica particles are dripping onto the coating during drying
Air interface is formed by silicone rubber or fluorine-based groups fixed on the gel, forming bumps on the surface of the coating.
SEM and transmission ratio are used (UV--vis)
Within the scope [lambda]= 200-1000 nm.
The AR coating is evaluated according to the load of modified silicone ,(0.
5 wt %, 1 wt % and 3 wt %)
Type of silica modification (
Silicone or fluoride)
Molecular weight of silicone rubber grafted silica gel (
Content of fluorine-based modified silica (fluorosilica-5, fluorine Silicon-
10, fluorine Silicon-30)was studied.
The transmission ratio of AR coating is affected by many factors, including the content of silica, the degree of dispersion of silica, the surface coverage of silica and the evaporation rate of solvent. The UV--
Visible spectrum of fluorine Silicon
10 and silicon fluoride-
Figure 30 shows the function loaded.
5 and 6, respectively. TheUV--
For comparison, the vis spectrum of pi is included in each diagram.
All coatings loaded with fluorine silica show a higher transmission ratio than pi films, which indicates an increase in AR properties of the coating.
As the concentration of silica increases from 0, the transmission ratio increases. 5% to 1%.
However, the average transmission ratio of the coating with a silicon content of 88% is 3%, which is comparable to the coating containing I % silica.
When pentone (CPT)
After use, the average transmission ratio of the three coatings is almost the same, but higher than pi (see Fig. 5b).
Regardless of the solvent, the coating has a considerable transmission ratio under the same silica load.
In cyclevone, the periodicity of interference seems to be more obvious than that of DMAc.
When Silicon fluoride-
30 for paint (see Fig. 6a and b)
In DMAc, the transmission ratio is proportional to the silica content, so the transmission ratio of all coatings is higher.
In CPT, however, the transmission ratio seems to have nothing to do with the silica load.
The transmission ratio did not increase significantly compared to pi, except for 3 wt %, the transmission spectra of AR coatings made of three different molecular weight silicone rubber modified silica particles in DMAc and CPT are shown below in Fig.
7 and 8, respectively (
Grafting silica with low molecular weight silicone: LPDMA-silica;
Positive migration silica gel of medium relative molecular mass: MPDMS-silica;
Grafting silicone rubber with high molecular weight: h principle-silica).
Unlike fluorine-silica gel, the transmission ratio of the coating did not increase with the increase of the colloidal content.
Packaging with 1% lmcp-
The silica in DMAc is shown to be 89%, an increase of 4% relative to pi, resulting in the highest transmission ratio.
Coating with 3% lmcp-
The transmission ratio of silica particles is lower, even lower than that of pi films. WhenLPDMS-
Silica was prepared in CPT, with an average transmission rate slightly higher than pi, but lower than the corresponding dmac formulation.
The transmission ratio seems to have nothing to do with the silicon content. For 1% MPDMS-
The transmission ratio of the silica coating is lower than that of the pi film below 700 nm, but higher than 700 nm (seeFig. 8a).
For the coating of 3% MPDMS-
Silica particles, in the range of 200 nm to 1000 nm, have lower transmission than pi films.
Loading as hpdm-
Silica particles from 0.
At 5% to 3%, the transmission ratio of the corresponding coating is gradually reduced until it is lower than pi (see Fig. 8b).
The influence of molecular weight (
Grafting onto silicone)
Regarding the AR attribute, as shown in the figure. 9.
The transmission ratio of AR coating is 0.
5% with the increase of silicone rubber molecules, the load of silicone rubber decreased slightly.
The transmission ratio of AR coating is below 1% nm, and the transmission ratio of 0 coating is the same as that of below 800 nm. 5% LPDMS-silica. The 1% LPDMS-
The emission of the silica AR coating is 89% higher than that of pi, 4%, while the emission of the other two molecular weight MPDMS and hpdm is lower than that of pi (see Fig. 9b).
For AR coatings containing 3% silicone rubber modified silica, the transmission ratio decreases with the increase of the molecular weight of silicone rubber under 700 nm.
At temperatures above 700 nm,
Principles of silica gel and h-
There is almost no difference in silicone. The 3%HPDMS-
Over the entire wavelength range, the transmission ratio of silica-containing coatings and any other ARcoatings in this study is the lowest.
Therefore, the molecular weight of the grafted MFC does affect the transmission ratio.
These data are related to fluorine Silicon (
430g/mol for hydrocarbon: C [H. sub. 2]C[H. sub. 2][C. sub. 8][F. sub. 17])
It can be speculated that higher molecular weight or higher grafting coverage is not necessarily better for AR performance.
To study the effect of solvent on AR properties, two solvents, CPT (cyclopentanone)and DMAc (
Thiamine B)
Was selected as a general solvent for the preparation of AR coatings.
The evaporation rate was only considered in this study.
There is no discussion about whether the interaction of solvent with polymer or colloidal is different.
Pi is soluble in CPT and DMAc.
The CPT theevapation rate is three times that of the DMAc determined byexposure 2 ml sample bottle solvent, in a one-month air cover.
In the case of preparing the coating with fluorine Silicon10 inCPT (see Fig. 5a)
, In DMAc, the average transmission ratio is equivalent to the same load (see Fig. 5b).
This means AR performance of fluorine Silicon
The coating has nothing to do with the steaming rate of the solvent type.
With the decrease of fluorineica-
10 to silicon fluoride-
30, the transmission of the coating prepared in CPT is lower than that prepared in DMAc (see Fig. 6a andb).
When CPT is used to prepare lsmc modified silica containing coating, its transmission is lower than that prepared with DMAc (seeFig. 7a and b).
In addition, unlike AR coatings from DMAc, AR coatings from CPT have similar transmission ratios throughout the colloidal load range.
Therefore, the choice of solvent and the activation rate of the solvent can play a certain role in the transparency of the paint.
SEM representation of AR coatings as hierarchical structures can influence and enhance surface roughness (42), (43)
The effect of solvent on the surface distribution of colloidal particles was studied by SEM.
In this study, surface coverage was calculated using image processing software.
SEM of silica-
10 and silicon fluoride-
In both DMAc and CPT, there are 30 images. 10-13.
Overall, SEM shows the random distribution of particles in the air
Coating interface.
It is also clear that surface coverage as a general trend depends on the colloidal load, but the load of 3 wt % indicates that this trend is not simple.
Quantification of surface coverage is listed in Table 3.
If there is no significant difference in aggregation, a higher coverage is expected to result in a higher transmission ratio.
In a coating containing 0.
5% of fluorine Silicon-
10, surface covering from 1. 7% in CPT to 2. 2% in DMAc.
And 1% fluorine-silicon coating-
In DMAc, the surface coverage rate of 10 is twice that of CPT, and 3% of fluorine Silicon-
10 of the coatings contained in the DMAc show 6.
3% surface coverage compared to 2. 5% in CPT.
Compared with the corresponding increase observed in DMAc, there was less increase in the coverage of colloidal surfaces in CPT.
Also observed in SEM (see Figs. 12 and 13)
The surface morphology of the coated substrate is smoother in dmac than in CPT.
As shown in the figure, a smooth background surface can reduce the optical loss by scattering, resulting in a higher transmission ratio7a and b.
For fluorine silica gel bodies with low molar content (fluorosilica-30)
, The coating in DMAc is much higher than the coating surface coverage in CPT.
In this case, the transmission ratio is also affected accordingly as the film surface coverage increases.
By comparing the coating of fluorine-containing silicon
10 with fluorine Silicon-
30 in samesolvent, the surface coverage of the former is higher than that of the latter.
The higher the Alkyflouro content, the more colloid on the surface.
Interestingly, the surface coverage of the coating is 0.
5% and 1% fluorine Silicon-
10 comparable to 1% and 3% fluorine Silicon in CPT
30, respectively in DMAc.
As expected, surface coverage data is consistent with transmission data (see Figs. 5and 6).
Interestingly, the accumulation of fluorine-Silicon Soil Colloid does not increase with the increase of load, which is contrary to the migration of silicone rubber.
Surface coverage of silica particles for lmcp-formulation coatingssilica, MPDMS-
Principles of silica gel and h-
Silica is calculated and listed in Table 4 and SEM and AFM images are shown from the figure. 14-17.
Surface coverage is expected to increase as the silica load increases.
With the increase of silicon concentration of lmcp-AR coating, the degree of aggregation increases
Silicone formulated inDMAc.
The combination of aggregation and surface coverage makes the effect of silicone rubber grafting on the transmission ratio more complicated.
AR coating of 0. 5% LPDMS-
Figure silica in DMAc
14a and d have very small aggregates with low surface coverage;
Therefore, the transparency of the film is slightly higher than that of the pi film.
As shown in the figure, similar images are obtained with AFM14d.
Severe aggregation was observed for 3% lmcp-
Silica coating in SEM and AFM images (see Fig. 14cand f)
, Which resulted in a lower transmission ratio of 0 compared to the other two AR coatings. 5% and 1%silica.
However, I % lmcp-Silica in DMAc (see Fig. 14b and e)
The highest coverage and moderate aggregation were shown from SEM and AFM images, which resulted in the highest transmission ratio (see Fig. 7a). WhenLPDMS-
In CPT (see Fig. 15)
With the increase of the colloidal content, the surface covering only increased slightly, but was lower than the coating prepared in DMAc.
All SEM images of ARcoatings with MPDMS-
Principles of silica gel and h-
Silica exhibits moderate to severe aggregation and low surface coverage (see Figs. 16 and 17).
This is consistent with the results of UV--
Visible transmission ratio (see Fig. 8).
Obviously, the longer the silicone rubber chain, the higher the tendency of colloidal aggregation.
SEM showed that when the surface of the modified silica gel is rough without significant aggregation, the reflection ratio of the polymer is suppressed (44). The MPDMS-
Principles of silica gel and h-
Silica aggregates are formed by entangled soft silicone rubber chains on the surface of the particles (45).
In the current work, Broadband AR coatings have been obtained in the wavelength regions of 400 to 1000 nm.
For 3% fluorine silicon, the emission gain of 4% and 3% is obtained10 and 1%
In the entire visible wavelength range, silica contains coatings, respectively. Using asol--
Li and others, gel method. (21-22), (26)
The maximum increase in transmission 2 was reported. 6%-4.
5%, but only at a specific wavelength, not the entire visible spectrum.
The peak transmission ratio is not related to the thickness of the film, which is not surprising.
In contrast, the AR layer is 250 nm, and the wavelength corresponding to the maximum transmission ratio is 1000 nm (7).
This explains why the transmission ratio of all AR coatings in this study (see Figs. 7-10)
With the increase of the wavelength, there is an increase in the overall trend, regardless of the molecular weight and solvent of the modified silicone grease, silicone rubber used.
More importantly, it was observed that as long as no obvious high concentration Silicon aggregation was formed from the SEM image, the transmission ratio increased with the increase of silica colloidal content, which was similar to the discovery of Li.
In their study, surface roughness was significantly enhanced when the number of deposition cycles increased.
With the increase of the number of deposition cycles, the maximum transmission ratio is reduced, because the silica nanoparticles that are subsequently adsorbed prefer to be filled or seated in the gap between the existing nanoparticles, resulting in more at the same time22).
The advantage of the colloidal method in this manuscript is that the transmission ratio is affected throughout the visible wavelength range and appears to have nothing to do with the wavelength (see Figs. 6-9).
This solution casting is simple and economical for large-scale production of ar coatings
Scale the substrate in industry compared to most previously reported processes.
Vacuum coating systems used in industry are more expensive and complex.
And other processes widely reported by other researchers, such as double coating and rotating coating technology (2), (21-26)
It\'s hard to scale-
Prepare for manufacturing
Conclusion in this study, several factors play a role in determining the properties of AR.
The influencing factors are: silica loading, molecular weight of grafted polymer, grafting density and solvent evaporation rate.
For fluorine-containing silicon coatings where aggregation is not a problem, a higher silica load increases the surface coverage and therefore a higher transmission ratio is obtained.
3% fluorine-silicon coating-10 (DMAc)
The highest transmission ratio of all AR coatings evaluated in this study was shown. For the PDMS-
In the silicon coating system, the relationship between the silicon load and the transmission ratio is more complicated.
Particle aggregation on the surface is observed.
Aggregation depends on the deposition and molecular weight of grafted silicone rubber.
The high molecular weight of silicone rubber chain on silica particles increases the aggregation of silica particles and reduces the transmission ratio.
However, among these two factors, the molecular weight of the grafted silicone rubber is more important than the load.
Solvent evaporation rate affects AR properties of fluorine-silicon coating and silicone rubber solution pouring methodSilicon coating.
A slower evaporation solvent facilitates the migration of silica particles
The coating interface results in a higher transmission ratio.
Roll toroll solution casting production line can manufacture AR coating.
The author thanks the doctor.
Dr. sumayajit SarkarBarton H.
Bobtonfor their great help in film actors.
To: M. D. Soucek; e-
Email: msoucek @ uakronedu DOI 10. 1002/pen.
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