Biodegradable Copolymers Obtained by Solution Polymerization

Miranda, Katiusca Wessler; Souza, Eduarda Cani de; Tomaz, Michele; Duarte, Marcia Adriana Tomaz; Pezzin, Sérgio Henrique

doi:10.1590/1516-1439.365514

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Articles • Mater. Res. 18 (suppl 2) • Dec 2015 • https://doi.org/10.1590/1516-1439.365514 copy

Biodegradable Copolymers Obtained by Solution Polymerization

Authorship SCIMAGO INSTITUTIONS RANKINGS

This study aims the synthesis of copolymers of poly (l-lactic acid) and polycaprolactone by ring opening polymerization. The reactions between l-lactide (LLA) and ε-caprolactone (CL) monomers, in 100/0, 95/5, 90/10 and 80/20 LLA/CL mass ratios, were conducted in refluxing toluene, using Stannous octoate as iniciator, methanol as co-iniciator and inert atmosphere (N₂). The reaction medium was maintained under stirring at 120 °C for 24 hours. The samples were characterized by carbon-13 and proton nuclear magnetic resonance (C¹³-NMR and H¹-NMR), and gel permeation chromatography (GPC). Monomers were characterized by thermogravimetry (TG). Copolymers were formed only in samples containing 20 wt% ε-caprolactone. NMR spectra of the other samples showed no evidence of CL units. This fact may be associated with the low-temperature volatilization of monomers. The GPC analysis showed that the increase of CL concentration decrease the molecular weight of copolymers.

Keywords:
ring opening polymerization; copolymer; poly(l-lactide acid); polycaprolactone

Reagents	100/0		95/05		90/10		85/15		80/20
Reagents	m (g)	n (mol)	m (g)	n (mol)	m (g)	n (mol)	m (g)	n (mol)	m (g)	n (mol)
LLA	50.0	0.3472	47.5	0.3298	45.0	0.3125	42.5	0.2951	40.0	0.2777
εCL	-	-	2.5	0.0219	5.0	0.0438	7.5	0.0657	10.0	0.0877
CH₃OH	7.8×10^-3	2.3×10^-4	7.8×10^-3	2.3×10^-4	7.8×10^-3	2.3×10^-4	7.8×10^-3	2.3×10^-4	7.8×10^-3	2.3×10^-4
Sn(Oct)₂	7.3×10^-3	2.3×10^-4	7.3×10^-3	2.3×10^-4	7.3×10^-3	2.3×10^-4	7.3×10^-3	2.3×10^-4	7.3×10^-3	2.3×10^-4
C₆H₅CH₃	43.3	0.4706	43.3	0.4706	43.3	43.3	43.3	0.4706	43.3	0.4706

	Literature				Experimental
Signal	Castro¹⁰10 Castro ML. Copolímeros estatisticos biodegradáveis de e-caprolactona e l,l-dilactídeo: síntese, caracterização e propriedades. [Thesis]. São Paulo: Escola Politécnica da Universidade de São Paulo; 2006.	Roa et al.¹⁵15 Roa JPB, Mano V, Faustino PB, Felix EB, Silva MESR and Souza JD Fo. Síntese e caracterização do copolímero poli(3-hidroxibutirato-co-ε-caprolactona) a partir de poli(3-hidroxibutirato) e poli(ε-caprolactona). Polímeros. 2010; 20(3):221-226. http://dx.doi.org/10.1590/S0104-14282010005000038. http://dx.doi.org/10.1590/S0104-14282010...	Chen et al.¹⁶16 Chen G-X, Kim H-S, Kim E-S and Yoon J-S. Synthesis of high-molecular-weight poly(l-lactic acid) through the direct condensation polymerization of l-lactic acid in bulk state. European Polymer Journal. 2006; 42(2):468-472. http://dx.doi.org/10.1016/j.eurpolymj.2005.07.022. http://dx.doi.org/10.1016/j.eurpolymj.20...	Motta & Duek⁴4 Motta EAR and Duek AC. Síntese, caracterização e degradação "in vitro" do Poli(L-ácido láctico). Polímeros Ciência e Tecnologia. 2006; 16(1):26-32. http://dx.doi.org/10.1590/S0104-14282006000100008. http://dx.doi.org/10.1590/S0104-14282006...	100/0	95/5	90/10	85/15	80/20
A	-	-	-	-	-	-	-	-	16.75
B	173.50	175	-	-	-	-	-	-	175.01
b1	169.60	-	169.53	166 and 169	169.6	169.6	169.6	169.60	169.59
C	69.06	-	68.93	69	69.02	68.98	68.98	68.96	69.23
c1	-	-	-	-	-	-	-	-	69.02
D	16	-	16.57	16.6	16.61	16.62	16.62	16.57	16.58
e	64.14	65	-	-	-	-	-	-	62.46
f	25	25	-	-	-	-	-	-	25.20
g	24	24	-	-	-	-	-	-	24.56
h	28	28	-	-	-	-	-	-	32.08
i	33	34	-	-	-	-	-	-	33.93

PCL		Poly(lactide acid)
Signal	Hydrogens	Signal	Hydrogens
2.64	-C(O)- CH₂ -CH₂-CH₂-CH₂-CH₂-O-	1.6	-C(O)-CH( CH₃ )-O-C(O)-CH(CH₃)-O-H
1.77	-C(O)-CH₂- CH₂ -CH₂-CH₂-CH₂-O-	1.5	-C(O)-CH(CH₃)-O-C(O)-CH( CH₃ )-O-H
1.86	-C(O)-CH₂-CH₂- CH₂ -CH₂-CH₂-O-	5.1	-C(O)- CH (CH₃)-O-C(O)-CH(CH₃)-O-H
1.77	-C(O)-CH₂-CH₂-CH₂- CH₂ -CH₂-O-	4.4	-C(O)-CH(CH₃)-O-C(O)- CH (CH₃)-O-H
4.43	-C(O)-CH₂-CH₂-CH₂-CH₂- CH₂ -O-

Samples	M_n	M_w	(Mw/Mn)
100/0	1.14×10⁴	2.89×10⁴	1.70
95/5	1.01×10⁴	1.60×10⁴	1.58
90/10	1.35×10⁴	2.00×10⁴	1.48
85/15	1.21×10⁴	2.14×10⁴	1.76
80/20	1.65×10³	2.10×10³	1.27

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