Preparation of functionalized precursor of SiC ceramic via hydrosilylation polymerization of 1,1-diphenylethylene derivatives

Figures & data

Figure 1. (a) The synthetic routes of monomers and polycarbosilane oligomers; x and y are the contents of β-addition and α-addition in corresponding oligomers, respectively and (b) the ¹H NMR spectra of polycarbosilane oligomers 1 and 2.

Figure 2. The kinetic curves of DPE-SiH/OMe hydrosilylation polymerization (a) Dependence of ln([SiH]₀/[SiH]) on the reaction time and (b) DP on the reaction time.

Table 1. The characteristics of DPE-SiH and DPE-SiH/OMe oligomers obtained by hydrosilylation polymerization.

Sample	Monomer	Mn^a (kg/mol)	PDI	DP^b	Mn^c (kg/mol)	β^d addition (%)	Tg (°C)	Td5^e (°C)	Wr^f (%)
1	DPE-SiH	1.7	2.61	5.9	1.4	88.8	14.3	270	84.8
2	DPE-SiH/OMe	2.1	2.64	6.3	1.7	88.0	24.6	345	91.0

^a Investigated by SEC.

^b The degree of polymerization, the ratio of integral for benzene rings and vinyl group in the chain end, calculated from the ¹H NMR spectra.

^c The number-average molecular weight calculated from M_n = M × DP, and M was the monomer molecular mass.

^d The proportion of β-addition among the polymer chain, calculated from the ¹H NMR spectra of the oligomer using Equation (1(1) ).

^e The temperature of sample weight loss 5%, investigated by TGA.

^f Weight residue at 400 °C and investigated by TGA.

Table 2. The kinetic results of DPE-SiH/OMe hydrosilylation polymerization.

Sample	Temp. (°C)	SiH/Pt	Mn^b (kg/mol)	PDI	DP^c	Mn^d (kg/mol)	k1 (×10^−2 h^−1)
I	100	1200	1.0	1.65	2.6	0.7	1.08
II	65	1200	1.5	1.95	5.2	1.4	1.25
III^a	65	600	0.9	1.5	3.4	0.9	1.58

^a The value was reaction for 192 h, and others were for 240 h.

^b Investigated by SEC.

^c The degree of polymerization, calculated from the ¹H NMR spectra of the oligomer using Equation (1(1) ).

^d The number-average molecular weight calculated from M_n = M × DP, and M was the monomer molecular mass.

Figure 3. The TGA curves of polycarbosilane oligomers 1 and 2 under nitrogen stream.

Figure 4. SEM images of SiC Ceramic cross section sintered form polycarbosilane oligomers 1 and 2.