Influence of the Fraction of Comonomers and Diluents on the Preparation of Polymeric Microspheres Based on Poly (Methacrylic acid-<i>co</i>-divinylbenzene) Obtained by Precipitation Polymerization

Piccaglia Neto, Mario; Castanharo, Jacira Aparecida; Oliveira, Márcia Gomes de; Costa, Marcos Antonio da Silva

doi:10.1590/1980-5373-MR-2017-0909

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Articles • Mat. Res. 22 (2) • 2019 • https://doi.org/10.1590/1980-5373-MR-2017-0909 copy

Influence of the Fraction of Comonomers and Diluents on the Preparation of Polymeric Microspheres Based on Poly (Methacrylic acid-co-divinylbenzene) Obtained by Precipitation Polymerization

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Preparation and characterization of polymeric microspheres based on poly(methacrylic acid-co-divinylbenzene) (P(MAA-co-DVB)) by precipitation polymerization are reported. The influence of the change in comonomer composition, crosslinking degree, ratio of total monomers/diluents by weight/volume (g/100 mL) and the volume ratio of diluents were studied. Spherical particles were obtained in the range from 1.42 to 8.41 µm. An increase in particle size and thermal resistance with decreasing molar fraction of methacrylic acid (MAA) were observed, associated with increases in critical chain length (CCL) and the number of crosslinks in this system, respectively. The analysis of particles with molar fraction of 50% MAA and acetonitrile/toluene volumetric ratio of 75/25 showed that larger particle size and yield were achieved with increasing ratio of total monomers/diluents (g / 100 mL). The particles prepared with 14% molar fraction of MAA obtained greater swelling ratios than the particles prepared with 50% MAA.

Keywords:
Precipitation polymerization; Microspheres; Swelling ratio

Molar fraction of methacrylic acid (%)	14	23	50	80
Average particle diameter (µm)	7.37	4.37	2.42	1.63
Yield (%)	43.0±4.3	43.3±4.3	64.3±6.4	49.7±5.0
Range of diameters (µm)	4.36 - 11.48	2.51 - 6.61	1.44 - 3.80	0.96 - 2.51
Variation of the diameter range with respect to the mean (%)	- 40.8 to + 55.9	- 42.5 to + 51.2	- 40.4 to + 56.9	- 41.5 to + 53.8
Standard deviation (µm)	2.17	1.15	0.68	0.47
Coefficient of variation (%)	29.5	26.3	28.2	28.5
Onset temperature (Co)	436	428	426	404
Derivative temperature (DTG) (Co)	466	458	452	451
Mass swelling ratio (%)	66.4	79.6	52.4	45.7
Standard deviation of swelling ratio (%)	8.9	12.5	9.6	5.0
Coefficient of variation of swelling ratio (%)	13.4	15.7	18.3	10.9
Confidence interval (%) with 95% confidence level	39.3 - 93.6	41.6 - 117.6	23.3 - 81.6	30.6 - 60.8

Diluents(s) or monomer	δ(Mpa^1/2) ^a	δ_d(Mpa^1/2) ^b	δ_p(Mpa^1/2) ^c	δ_h(Mpa^1/2) ^d
Acetonitrile	24.43	15.34	18.00	6.14
Acetonitrile/Toluene 75/25 (V/V)	23.04	16.06	15.60	5.41
Acetonitrile/Toluene 50/50 (V/V)	21.55	16.74	12.77	4.58
Toluene	18.21	18.04	1.43	2.05
Divinylbenzene	19.90	18.60	1.00	7.00
Methacrylic acid	19.01	15.80	2.80	10.20

Ratio of total monomers / diluents (g/100 mL)	Average particle diameter (µm)	Polymerization yield (%)	Diameter range studied (µm)	Diameter range variation in relation to the average (%)	Standard deviation (µm)	CV^* * CV = variation coefficient (%)
2.0	very low yield	2.4±0.2	-	-	-	-
3.0	1.42	34.6±3.5	0.83 - 2.19	-41.4 to +54.0	0.40	28.5
4.0	2.42	64.3±6.4	1.44 - 3.80	-40.4 to +56.9	0.68	28.2
5.0	2.86	71.9±7.2	1.66 - 4.36	-42.1 to +52.2	0.78	27.1
6.7	coagulated	79.3±7.9	-	-	-	-
8.0	coagulated	83.4±8.3	-	-	-	-
10.0	coagulated	87.8±8.8	-	-	-	-
12.0	coagulated	95.8±9.6	-	-	-	-

Acetonitrile/toluene volumetric ratio (v/v)	Molar fraction of metacrylic acid (%)	Average particle diameter (µm)	Diameter range of particles (µm)	Diameter range variation (%)	Standard deviation (µm)	Particle size coefficient of variation ratio (%)	Particle yield (%)
100/0		2.82	1.66 -4.36	-41.2 to +54.7	0.85	30.2	47.2±4.7
75/25	50	2.42	1.44 – 3.8	-40.4 to +56.9	0.68	28.2	64.3±6.4
50/50		microgel	microgel	microgel	microgel	microgel	microgel
100/0		5.64	3.31 – 8.71	-41.3 to +54.5	1.65	29.3	37.9±3.8
75/25	14	7.37	4.36 – 11.48	-40.8 to +55.9	2.17	29.5	43.0±4.3
50/50		microgel	microgel	microgel	microgel	microgel	microgel

Acetonitrile/toluene volumetric ratio (v/v)	Molar fraction of metacrylic acid (%)	Average particle diameter (µm)	Diameter range of particles (µm)	Diameter range variation (%)	Standard deviation (µm)	Particle size coefficient of variation ratio (%)	Particle yield (%)
100/0		8.41	5.01 – 13.18	-40.4 to +56.8	2.53	30.1	45.2±4.5
75/25	50	coagulated					79.3±7.9
50/50		microgel					microgel
100/0		5.68	3.31 – 8.71	-41.7 to +53.4	1.70	30.0	46.8±4.7
75/25	14	coagulated					76.1±7.6
50/50		microgel					microgel

Acetonitrile/toluene volumetric ratio (v/v)	Molar fraction of metacrylic acid (%)	Mass swelling ratio (%)	Standard desviation (%)	Coefficient of variation of swelling ratio (%)	Confidence interval (%) with 95% confidence level
100/0		29.6	5.3	18.1	13.3-45.9
75/25	50	52.4	9.6	18.3	23.3-81.6
50/50		75.5	5.7	7.5	58.2-92.8
100/0		38.0	5.7	14.9	20.8-55.2
75/25	14	66.4	8.9	13.4	39.3-93.6
50/50		137.8	19.2	14.0	79.4=196.3

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