Evolution of molecular composition of polycarbosilane and its effect on spinnability

Abstract

The molecular composition of polycarbosilane (PCS) and its evolution in the synthesis process, as well as the contribution of each component to the spinnability of PCS, were explored by combining distillation separation with gel permeation chromatogram peak-splitting. The results show that PCS is composed of four kinds of molecules with different structures, namely M L , M M , M H , and M SH (number-average molecular weights of 531, 1207, 2731, and 10 977, respectively). In the synthesis process, PCS changed from containing two components to three components, and finally to four components. The PCS can be spun when it is composed of M L , M M , and M H , but is not suitable for spinning when it is composed of one, two, or four components. For a PCS having three components, increasing the amount of M H and restricting M L to within a certain range can enhance the spinnability of PCS. The underlying mechanism is controlled by the linear structure of M H and its low melting point by there being an appropriate M L content, which ensures melting, de-foaming, and stability in spinning. The final optimum ratio is found to be an M H content of 30-45%, an M M content of 30-51%, and an M L content of 18-25%.

Tomographic Volumetric Additive Manufacturing of Silicon Oxycarbide Ceramics

“…In the pyrolyzed state, the bands appear as a smoother curve presenting mainly SiO‐ and SiC‐type bonds after ceramization. Both spectra are in good agreement with prior work of the exact same PCP in the green state, including the added cross‐linker and photoinitiator, [ 27,30,36–42 ] and in the pyrolyzed state. [ 27,31,36 ] As shown in Figure 4b, Raman spectroscopy of green bodies and pyrolyzed parts suggests a conversion from an organic to an inorganic material after pyrolysis.…”

Salt-Templated Solvothermal Synthesis of Dioxane-Linked Three-Dimensional Nanoporous Organic Polymers for Carbon Dioxide and Iodine Capture

“…The formation of 3D-tPOPs was confirmed by using Fourier transform infrared (FTIR) spectroscopy analysis (Figure a). The FTIR spectra revealed the disappearance of C–F vibration bands of TFPN and −Si­(CH 3 ) 3 signals of OTMSTP at ∼1317 and ∼832 cm –1 , respectively. , Moreover, the appearance of the C–O stretching band at ∼1254 cm –1 along with the retention of nitrile stretching band at ∼2253 cm –1 verified the formation of 3D-tPOPs. , In addition, the disappearance of the −C–O–Si– vibration band at ∼1172 cm –1 further confirmed the successful polymerization . Interestingly, the intensities of the −C–H and −Si–C– stretching bands at ∼2956 and ∼740 cm –1 , respectively, for the polymers prepared through the templated synthesis are lower compared to those for the nontemplated sample (Figure S6), implying a higher degree of polymerization in the templated samples .…”

“…The FTIR spectra revealed the disappearance of C−F vibration bands of TFPN and −Si(CH 3 ) 3 signals of OTMSTP at ∼1317 and ∼832 cm −1 , respectively. 30,31 Moreover, the appearance of the C−O stretching band at ∼1254 cm −1 along with the retention of nitrile stretching band at ∼2253 cm −1 verified the formation of 3D-tPOPs. 30,32 In addition, the disappearance of the −C−O−Si− vibration band at ∼1172 cm −1 further confirmed the successful polymerization.…”

Wastewater depollution of textile dyes and antibiotics using unmodified and copper oxide/zinc oxide nanofunctionalised graphene oxide materials

“…After adsorption of antibiotics on GO, the peaks at 1575 cm −1 and 1065 cm −1 owing to CC and C–O–C respectively were slightly diminished, and chemical signatures at 1400 cm −1 and 1242 cm −1 were prominent/appeared owing to C–H and C–H 3 vibrations respectively. 77 Significant differences were not observed in the ATR-FTIR spectra after adsorption of dyes and antibiotics on CuO-rGO and ZnO-rGO and this might have occurred due to the overlapping of the IR measurement peaks. However absorbance at 1567 cm −1 of ATR-FTIR spectra owing to the CC bonding recorded significant changes on GO after adsorption of both dyes and antibiotics on CuO-rGO (Fig.…”