Complex-mediated microwave-assisted synthesis of polyacrylonitrile nanoparticles

Figures & data

Scheme 1 a) Formation of [Co(III)en₂Cl₂]Cl complex (I), and b) coordination of monomer acrylonitrile (AN) with [Co(III)en₂Cl₂]Cl.

Table 2 Variation of particle size in microwave and conventional processes at different concentrations of complex at [AN] = 2.0 × 10⁻² mol dm⁻³, [APS] = 10.0 × 10⁻³ mol dm⁻³

[Co(III)en2Cl2]Cl (mol dm^−3)	Diameter of particle (nm)
	Microwave process	Conventional process
0	347	454
2	50	40
4	67	86
8	79	98
12	88	111
16	101	122
20	115	147

Abbreviations: AN, acrylonitrile; APS, ammonium persulfate.

Table 1 Effect of concentration of AN, APS, and [Co(III)en₂Cl₂]Cl on the % conversion and Rp by microwave and conventional processes and on Mv and Mn by viscosity and GPC methods of PAN

[AN] × 10^−2	[Co(III)en2Cl2]Cl		MW irradiation process		Heating process		Molecular weight by MW process
mol dm^−3	mol dm^−3	× 10^−3 mol dm^−3	Conversion (%)	Rp × 10^6 dm^−3s^−1	Conversion (%)	Rp × 10^8 dm^−3s^−1	Mv × 10^−6	Mn × 10^−6
0	10.0	10.0	0.0	0.0	0.0	0.0	–	–
0.5	10.0	10.0	86.22	3.6	62.89	6.90	1.07	0.87
1.0	10.0	10.0	87.16	7.45	67.32	12.43	1.45	1.0
1.5	10.0	10.0	88.12	9.98	70.43	15.45	1.78	1.22
2.0	10.0	10.0	90.46	10.92	71.90	16.56	2.03	1.54
2.5	10.0	10.0	89.0	11.45	70.34	17.56	2.34	1.78
3.0	10.0	10.0	87.43	12.32	69.98	18.87	2.65	2.01
3.5	10.0	10.0	84.56	12.89	67.67	19.67	2.89	2.34
2.0	0	10.0	0.0	0.0	0.0	0.0
2.0	2.5	10.0	67.84	5.67	56.65	14.78
2.0	5.0	10.0	75.98	8.5	65.89	15.89
2.0	10.0	10.0	90.46	10.92	71.90	16.56
2.0	15.0	10.0	91.02	11.56	72.21	16.97
2.0	20.0	10.0	91.34	11.87	72.87	17.22
2.0	25.0	10.0	91.78	12.02	73.03	17.99
2.0	10.0	0	5.98	0.12	1.23	0.20
2.0	10.0	2.5	69.98	5.67	49.98	9.12
2.0	10.0	5.0	80.45	8.23	51.23	11.34
2.0	10.0	10.0	90.46	10.92	68.85	14.32
2.0	10.0	15.0	90.98	11.89	71.90	16.56
2.0	10.0	20.0	91.34	12.43	72.23	18.20
2.0	10.0	25.0	91.56	12.86	72.67	18.65

Notes: Polymerization rates (Rp) are presented for microwave oven for 240 s and for conventional heating at 50°C for 3 h.

Abbreviations: AN, acrylonitrile; APS, ammonium persulfate; Rp, rate of polymerization; Mv, viscosity average molecular weight; Mn, number average molecular weight; GPC, gel permeation chromatography; PAN, polyacrylonitrile nanoparticles; MW, microwave.

Figure 1 Spectral evidence for the interaction of Co-complex, APS, and AN: a) CoCl₂; b) [Co(III)en₂Cl₂]Cl; c) [Co(III)en₂Cl₂]Cl + APS + AN before reaction; and d) [Co(III)en₂Cl₂]Cl + APS + AN after reaction.

Abbreviations: AN, acrylonitrile; APS, ammonium persulfate.

Figure 2 % conversion PAN (a) in microwave oven and (b) in conventional heating.

Abbreviation: PAN, polyacrylonitrile nanoparticles.

Figure 3 Dependence of the reciprocal of degree of polymerization (1/DP) of AN on Rp on varying [APS]; from 2.5 × 10⁻³ to 25 × 10⁻³ mol dm⁻³ at [AN] = 2 mol dm⁻³, and [Co(III)en₂Cl₂]Cl = 10 × 10⁻³ mol dm⁻³.

Abbreviations: AN, acrylonitrile; APS, ammonium persulfate; Rp, rate of polymerization; 1/DP, reciprocal of degree of polymerization.

Figure 4 Variation of sound velocity with molecular weight of PAN solution in DMF at 30°C.

Abbreviations: PAN, polyacrylonitrile nanoparticles; DMF, dimethylformamide.

Figure 5 SEM of PAN nanoparticle prepared by MW irradiation at different magnification.

Abbreviations: SEM, scanning electron microscope; PAN, polyacrylonitrile nanoparticles; MW, microwave.

Figure 6 TEM of PAN nanoparticle by (a) MW irradiation and (b) conventional heating methods.

Abbreviations: TEM, transmission electron microscope; PAN, polyacrylonitrile nanoparticles; MW, microwave.