A new initiating system based on [(SiMes)Ru(PPh₃)(Ind)Cl₂] combined with azo-bis-isobutyronitrile in the polymerization and copolymerization of styrene and methyl methacrylate

Figures & data

Table 1. Polymerization conditions of styrene, methyl methacrylate and their copolymerization.

Copolymer	St (g)	St (mol. × 10^2)	MMA (g)	MMA (mol. × 10^2)	Yield (wt %)
PS	3.64	3.50	–	–	79.38
PSMMA90	3.27	3.14	0.37	0.37	81.25
PSMMA75	2.81	2.70	0.91	0.91	74.48
PSMMA50	1.87	1.80	1.87	1.87	75.55
PSMMA25	0.91	0.88	2.81	2.81	75.18
PSMMA10	0.37	0.36	3.27	3.27	89.03
PMMA	–	–	3.74	3.74	76.75

Notes:

[AIBN] = 2.0 mg (1.22.10⁻⁵ mol); M₂₀ = 11.3 mg (1.22.10⁻⁵ mol); aging time of AIBN/M₂₀ system: 5 min; aging temperature: 80 °C; polymerization temperature: 80 °C; polymerization time: 2 h; M₂₀/AIBN = 1.0 (mol mol⁻¹).

Table 2. Molar fractions of comonomers St (f_St) and MMA (f_MMA) before the copolymerization reaction and those incorporated in the PSMMA copolymers (F_St) and (F_MMA).

Copolymer PSMMA	fSt	fMMA	FSt		FMMA		Conversion (%)
			^13C NMR	^1H NMR	^13C NMR	^1H NMR
PSMMA10	0.094	0.905	0.166	0.180	0.834	0.82	8.92
PSMMA25	0.237	0.763	0.578	0.545	0.422	0.455	5.11
PSMMA50	0.444	0.555	–	0.608	–	0.392	6.52
PSMMA75	0.650	0.350	–	0.560	–	0.440	5.42
PSMMA90	0.892	0.107	–	0.95	–	0.05	7.37

Table 3. Variation of the yield, molecular weight and polydispersity index in the polymerization of PSt vs. the aging time of the initiator system.

Experiment	Aging time (min)	Yield (%)	(g mol^−1) × 10^−4	(g mol^−1) × 10^−4
1	5	79.18	9.58	12.17	1.27
2	25	72.26	9.04	11.03	1.22
3	30	65.35	7.52	9.85	1.32
4	60	58.10	7.42	8.89	1.20
5	120	43.26	5.32	6.75	1.27

Notes:

Aging temperature: 80 °C; polymerization temperature: 80 °C; polymerization time: 2 h; St = 3.64 g (3.50 × 10⁻² mol); AIBN = 2.0 mg (1.22.10⁻⁵ mol); M₂₀/AIBN = 1.0 (mol mol⁻¹).

Table 4. Variation of the yield, molecular weight and polydispersity index in the polymerization of MMA vs. the aging time of the initiator system.

Experiment	Aging time (min)	Yield (%)	(g mol^−1) × 10^−4	(g mol^−1) × 10^−4
1	5	78.23	9.68	11.90	1.23
2	25	59.53	6.97	9.03	1.30
3	30	52.25	5.92	7.91	1.34
4	60	40.90	5.41	6.30	1.16
5	120	38.86	4.95	6.01	1.21

Notes:

Aging temperature: 80 °C; polymerization temperature: 80 °C; polymerization time: 2 h; MMA = 3.74 g (3.74 × 10⁻² mol); AIBN = 2.0 mg (1.22.10⁻⁵ mol); M₂₀/AIBN = 1.0 (mol mol⁻¹).

Figure 1. FTIR spectra of PSt, PMMA and PSMAA25 films.

Figure 2. ¹³C NMR spectra of PSt, PMMA and PSMMA50 obtained in CDCl₃.

Figure 3. ¹H NMR spectra of PSt, PMMA and PSMMA50 obtained in CDCl₃.

Figure 4. Mayo–Lewis plots, the variation of r_St vs. r_MMA for PSMMA.

Figure 5. Deconvolution of the ¹H NMR spectra (1.10–2.15 ppm) of PSt, PSMMA and PSMMA25 via lorentzian peaks.

Table 5. Molecular weight distribution of polystyrene, poly(methylmethacrylate) and poly(styrene-co-methylmethacrylate) copolymers with different St/MMA compositions.

System	Composition St:MMA (g%)	(g mol^−1)	(g mol^−1)	(g mol^−1)
PS	–	8.75	11.11	11.84	1.269
PSMMA1	90:10	5.72	6.87	–	1.200
PSMMA2	75:25	5.21	6.50	–	1.247
PSMMA3	50:50	5.97	7.17	–	1.201
PSMMA4	25:75	8.80	9.64	–	1.095
PSMMA5	90:10	4.34	6.10	–	1.407
PMMA	–	11.72	13.33	11.78	1.137

Figure 6. DSC thermograms of PSt, PMMA and PSMAA obtained with a heating rate of 20 °C min⁻¹.

Figure 7. TGA and DTA curves of PMMA, PSt and PSMMA spectra obtained at a heating rate of 10 °C min⁻¹.

Figure 8. SEM micrographs of PMMA, PSt, and PSMMA specimens.

Scheme 1. Scheme of the polymerization and copolymerization of styrene and methyl methacrylate using the M₂₀/AIBN system.

Scheme 2. Proposed mechanism of polymerization and copolymerization of styrene and methyl methacrylate using the M₂₀/AIBN system.