Abstract:A silicon oxide film doped with fluorine was grown on a (100)-oriented Si wafer through liquid-phase deposition (LPD) as a protective mask of the wafer's rear side in order to chemically texture the wafer's unprotected front side in a basic etching bath, which is a new process in solar-cell manufacturing. The growth rate of the LPD-SiO2 film increased monotonically with an increase of the deposition temperature up to 60 °C for a given precursor solution. Field-emission scanning electron microscopy (FE-SEM) ind… Show more
“…Second, a free-standing flexible film of PFCB-Si is also prepared by a two-step procedure as described in the Experimental Section. Usually, TEOS-based solid films, prepared by chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), are hard and brittle. , No reports on the free-standing TEOS-based solid films have been found. This contribution first provides a highly transparent and flexible polysiloxane film (Figure b) derived from TEOS.…”
A novel
fluorinated macromonomer (TFVE-Si) with four functional groups derived
from easily available tetraethoxysilane (TEOS) has been successfully
synthesized through the Piers–Rubinsztajn reaction using B(C6F5)3 as a catalyst. This procedure efficiently
avoids the generation of Si–OH and −Si–CH2–CH2– groups, which greatly affect
the properties of the organosiloxanes. Prepolymerizing the macromonomer
in mesitylene solution gives an oligomer which can form a flexible
and highly transparent free-standing cross-linked polysiloxane film
followed by a postpolymerization procedure at high temperature. The
cross-linked polysiloxane (thickness = 2 mm) shows a transmittance
of higher than 91% in the visible region and an absorbance of near
100% in the UV region (<350 nm), exhibiting its potential application
as a transparent coating for blocking ultraviolet rays in both household
and industrial uses. In particular, the cross-linked film shows low
dielectric constant (D
k
) of 2.50 and low dissipation factor (D
f
) of 4.0 × 10–3 at an ultrahigh
frequency of 10 GHz. This is the first example of nonporous polysiloxane
having both low D
k
and D
f
while conventional TEOS-based
polymers exhibit higher D
k
(>3.0). Moreover, D–E loop tests illustrate that the cross-linked polysiloxane possesses
excellent linear dielectric properties, further suggesting its good
insulating properties. Furthermore, the prepared polysiloxane exhibits
high thermostability with a 5 wt % loss temperature of 476 °C
and a glass transition temperature (T
g) of 110 °C as well as good mechanical strength (with an elastic
modulus of 1.1 GPa). Because of the existence of fluoro-containing
groups, the polysiloxane also shows high hydrophobicity. Furthermore,
TFVE-Si can efficiently improve the T
g of linear polysiloxane prepared from dimethylsiloxane with two functional
groups. These indicate that the fluorinated TEOS has potential application
in the microelectronics industry; especially, it can meet the requirement
of the high-frequency communication fields for the materials with
both low D
k
and D
f
.
“…Second, a free-standing flexible film of PFCB-Si is also prepared by a two-step procedure as described in the Experimental Section. Usually, TEOS-based solid films, prepared by chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), are hard and brittle. , No reports on the free-standing TEOS-based solid films have been found. This contribution first provides a highly transparent and flexible polysiloxane film (Figure b) derived from TEOS.…”
A novel
fluorinated macromonomer (TFVE-Si) with four functional groups derived
from easily available tetraethoxysilane (TEOS) has been successfully
synthesized through the Piers–Rubinsztajn reaction using B(C6F5)3 as a catalyst. This procedure efficiently
avoids the generation of Si–OH and −Si–CH2–CH2– groups, which greatly affect
the properties of the organosiloxanes. Prepolymerizing the macromonomer
in mesitylene solution gives an oligomer which can form a flexible
and highly transparent free-standing cross-linked polysiloxane film
followed by a postpolymerization procedure at high temperature. The
cross-linked polysiloxane (thickness = 2 mm) shows a transmittance
of higher than 91% in the visible region and an absorbance of near
100% in the UV region (<350 nm), exhibiting its potential application
as a transparent coating for blocking ultraviolet rays in both household
and industrial uses. In particular, the cross-linked film shows low
dielectric constant (D
k
) of 2.50 and low dissipation factor (D
f
) of 4.0 × 10–3 at an ultrahigh
frequency of 10 GHz. This is the first example of nonporous polysiloxane
having both low D
k
and D
f
while conventional TEOS-based
polymers exhibit higher D
k
(>3.0). Moreover, D–E loop tests illustrate that the cross-linked polysiloxane possesses
excellent linear dielectric properties, further suggesting its good
insulating properties. Furthermore, the prepared polysiloxane exhibits
high thermostability with a 5 wt % loss temperature of 476 °C
and a glass transition temperature (T
g) of 110 °C as well as good mechanical strength (with an elastic
modulus of 1.1 GPa). Because of the existence of fluoro-containing
groups, the polysiloxane also shows high hydrophobicity. Furthermore,
TFVE-Si can efficiently improve the T
g of linear polysiloxane prepared from dimethylsiloxane with two functional
groups. These indicate that the fluorinated TEOS has potential application
in the microelectronics industry; especially, it can meet the requirement
of the high-frequency communication fields for the materials with
both low D
k
and D
f
.
“…There was also irritant gas generated in the experiment, it was speculated it was the formation of HF. The chemical reactions during deposition were summarized below [24]: Figure 6 Schematic diagram of coating deposition mechanism on carbon fibres by liquid phase deposition.…”
Section: Resultsmentioning
confidence: 99%
“…There was also irritant gas generated in the experiment, it was speculated it was the formation of HF. The chemical reactions during deposition were summarized below [24]:…”
In this study, SiC coating was prepared on carbon fibres from solution at ambient temperatures for the first time. The thickness of the coating was ∼85 nm. Analysis of the coatings revealed the presence of only SiC in the coating. The initial oxidation temperature of the SiC-coated carbon fibres increased by ∼50°C and the complete oxidation temperature was increased by ∼167°C, indicating excellent oxidation resistance owing to the presence of the SiC coating. We believe that the excellent properties and easy preparation process of SiC coating reported in this paper would provide us with a new way to produce SiC coating on carbon substrates.
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