Synthesis and Characterization of Poly(ethylene-co-vinyl alcohol)-graft-poly(ε-caprolactone)

Abstract

ABSTRACT:Graft poly(ε-caprolactone)s (PCLs) with high graft density were synthesized by using random copolymer poly(ethylene-co-vinyl alcohol) (EVOH) to initiate ring-opening polymerization of ε-caprolactone, with and without cocatalyst Sn(Oct) 2 . The graft copolymer were characterized by IR, 1 H and 13 C NMR. The solution property and the crystallization behavior were also investigated.KEY WORDS Poly(ε-caprolactone) (PCL) / Poly(ethylene-co-vinyl alcohol) (EVOH) / Graft Copolymer / Poly(ε-caprolactone) (PCL) is a central important environmental friend and biocompatible polymer. It was synthesized through ring opening polymerization of ε-caprolactone (ε-CL) with various initiators or catalysts. 1, 2 Recently, macromolecular engineering of PCL 3 was also developed in order to synthesize block, graft and hyperbranched (co)polymers.Graft copolymerization of ε-CL can improve the mechanical properties of the homopolymers and the product can also be used as compatibilizer in polymer blends. There are generally two approaches to prepare graft copolymer of PCL. One of them is the macromonomer technique, in which PCL bearing a terminal double bond was synthesized beforehand. Using this approach, Jérôme and co-workers synthesized well-defined polystyrene-g-PCL, 4 poly(alkyl methacrylate)-g-PCL, 5 and poly(norborn-ene)-g-PCL 6 by controlled radical or organometallic catalyzed copolymerization of corresponding monomers and premade PCL macromonomers. The other approach is the "grafting form" technique in which the polymerization of ε-CL is (co)initiated by pendent hydroxyl group of a polymer backbone. For example, many natural polyhydroxy macromolecules such as starch, 7 dextran, 8 chitin, 9 and hydroxycellulose, 10 as well as synthetic polymers such as polyvinyl alcohol, 11 poly(ethylene-co-vinyl alcohol) (EVOH) 12 and functionalized polypropylene, 13 were grafted with PCL by ring opening polymerization from their pendent hydroxyl group. In addition, samarium-mediated graft polymerization of ε-CL on functionalized poly(pxylylene)s was also achieved. 14 In this paper, we report the synthesis and properties of a highly grafted copolymer, EVOH-g-PCL. The product is different from that in ref 12 in graft den- † To whom correspondence should be addressed. sity because the hydroxyl content of EVOH in ref 12 ranges from 3.1 to 6.7 mol% and we use EVOH with much larger hydroxyl contents in this work. Therefore the graft density is so high that the copolymer exhibits special solution and crystallization properties. We will discuss these in details in the following. And the graft copolymer can lead to different end applications, for instance, hand-mouldable and degradable package. EXPERIMENTAL Materialsε-Caprolactone (Aldrich, 99%) was distilled over calcium hydride under a reduced pressure before use. EVOHs (ethylene content 44 mol% and 27 mol%, Aldrich; ethylene content 32 mol%, Kuraray, Japan) were dried at 50 • C in vacuo for 24 h. Stannous 2-ethylhexanoate (Aldrich, 95%) was used as received. PolymerizationIn a typical experime...

Solubility-governed architectural design of polyhydroxyurethane-graft-poly(ε-caprolactone) copolymers

“…Sn-based catalysts, and specifically Sn(Oct) 2 , are well known to induce such side reactions, 53 in linear 49,[54][55][56] and more complex architectures such as star 57 or graft (co)polymers. 58,59 Similarly, transesterification has been observed in some sulfonic acid-catalyzed polymerizations of CL and other lactones towards linear and star-based homoor copolymers. [60][61][62][63][64] Due to the abundance of hydroxyl groups and at high catalyst loadings (CL 100 MSA 3 , CL 100 Sn 1 ), transesterification may take place already from the early stages of the reaction, but at a lower rate compared to the polymerization rate.…”

“…After 24 h the samples had gelled, similarly to what has been previously observed in graft copolymers of poly(ethylene-co-vinyl alcohol) and CL. 58 The samples with higher CL loadings, CL 50 Sn 0.02 and CL 100 Sn 0.02 , reached high conversion, ≥85%, after 8 h and the M n increased continuously during the total 24 h of reaction time. Đ increased more modestly compared to the reactions with a low CL loading, with a slightly higher value for CL 50 Sn 0.02 than CL 100 Sn 0.02 .…”

Poly (ethylene-co-vinyl alcohol)-based polymeric thermo-responsive nanocarriers for controlled delivery of epirubicin to hepatocellular carcinoma

“…The reference peaks of components comprising RA (around 1.00 (s, 6H, –(CH3)2 geminal groups on ring), 1.40-1.50 (m, 4H, –CH2–CH2– in ring), 1.70 (s, 3H, –CH3 group on cyclohexene ring bonded to –C=C–), 2.00 (m. 5H, –CH2, and –CH3 groups), 2.30 (s, 3H, –CH3 group next to the carboxylic moiety), 5.80 (s, 1H, proton next to the –(C=O)O– group), 6.00-6.50 (m, 4H, vinylic protons), and 7.00 (m, 1H (vinylic proton) ppm)(10), succinate subunit (2.50 ppm(–CH2–CH2– moiety)), EVOH (1.5 (bs, 3H, –CH3), 2.05 (m, –CH2–CH2– (ethylenic moiety), around 3.70 (m, –CH2–CH(OH) – and 4.20 (s, 1H, –CH2–CH(OH)– ppm)(1112) and PEGS (3.2 ppm, (OCH 3 ), 3.5 ppm, (–CH 2 CH 2 – of PEG moiety) and 2.50 (CH 2 CH 2 of succinate moiety)) were clearly visible in the final conjugates spectra at the right places with the accurate intensity as predicted. Similarly, the IR bands related to conjugate components were clearly seen in spectral regions for EVOHS, RA, and PEG respectively around 3370, 2929, 1727, 1673, 1109 cm -1 (Fig.…”

Synthesis and characterization of poly(ethylene-vinyl alcohol)-g-poly(phenyl ethyl methacrylate) copolymers by a grafting onto method

“…Ethylene-vinyl alcohol copolymer (EVOH) has invoked particular interest. There are examples of modification of EVOH by conventional esterification to produce a polyethylene chain backbone with attached carboxyl groups [9], phthalate derivatives [10] and side chains of stearly groups [11], methyl methacrylate [12], lactic acid [13] and caprolactone [14,15].…”