Synthesis and Micellization of Thermosensitive PNIPAAm-b-PLA Amphiphilic Block Copolymers Based on a Bifunctional Initiator

Feng Xu; Ting-Ting Yan; Yan-Ling Luo

Macromolecular Research, Vol.19, No.12, 1287-1295, December, 2011

DOI10.1007/s13233-011-1209-x Export Citation

Synthesis and Micellization of Thermosensitive PNIPAAm-b-PLA Amphiphilic Block Copolymers Based on a Bifunctional Initiator

Feng Xu^†, Ting-Ting Yan, and Yan-Ling Luo^†

Key Laboratory of Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi’an, 710062, P. R. China

E-mail:,

The thermo-sensitive amphiphilic block copolymer poly(N-isopropylacrylamide)-block-poly(D,L-lactide)(PNIPAAm-b-PLA) was synthesized using a simple free radical copolymerization route based on a bifunctional initiator, 2,2-azobis(2-methylpropion amidine) dihydrochloride followed by the ring-opening polymerization of D,L-actide in the presence of a Sn(Oct)2 catalyst. The chemical structure of the PNIPAAm-b-PLA copolymers was verified using Fourier transform-infrared spectrophotometry and nuclear magnetic resonance, and the molecular weight and polydispersity index were examined using gel permeation chromatography. The amphiphilic PNIPAAm-b-PLA block copolymers could self-assemble into spherically shaped micelles in an aqueous solution with a transmission electron microscopy diameter range of 40-56 nm and a dynamic laser scattering hydrodynamic diameter of 90-200 nm. This behavior depends on the environmental temperature, the hydrophobic interactions among PNIPAAm molecular chains, the intermolecular hydrogen bonding between the PNIPAAm chains and water molecules, and the intramolecular hydrogen bonding between the -CONH2 groups. The copolymers held a critical micellization concentration of 4.93-7.21 mg·L-1 and a low critical solution temperature of 31.15- 32.62 ℃ being more or less affected by their compositions, PLA or PNIPAAm block length, and polymerization temperature. The as-prepared PNIPAAm-b-PLA block polymers are anticipated to be applied as candidate drug release carriers.

Keywords:block copolymers;bifunctional initiators;poly(N-isopropylacrylamide);thermo-sensitivity;micelles.

[References]

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[Referenced By]

[1] Rosler A, Vandermeulen GWM, Klok HA, Adv.Drug Deliv. Rev., 53, 95 (2001)

[2] Torchilin VP, J. Control. Release., 73, 137 (2001)

[3] Kwon GS, Kataoka K, Adv. Drug Deliv. Rev., 16, 295 (1995)

[4] Li J, Li X, Ni XP, Leong KW, Macromolecules, 36(8), 2661 (2003)

[5] Loh XJ, Wu YL, Seow WTJ, Norimzan MNI, Zhang ZX, Xu F, Kang ET, Neoh KG, Li J, Polymer, 49(23), 5084 (2008)

[6] Satturwar P, Eddine MN, Ravenelle F, Leroux JC, Eur. J. Pharm. Biopharm., 65, 379 (2007)

[7] Na K, Lee KH, Bae YH, J. Control. Release., 97, 513 (2004)

[8] Kohori F, Sakai K, Aoyagi T, Yokoyama M, Sakurai Y, Okano T, J. Control. Release., 55, 87 (1998)

[9] Chung JE, Yokoyama M, Yamato M, Aoyagi T, Sakurai Y, Okano T, J. Control. Release., 62, 115 (1999)

[10] Choi C, Chae SY, Nah JW, Polymer, 47(13), 4571 (2006)

[11] Lefaux CJ, Zimberlin JA, Dobrynin AV, Mather PT, J. Polym. Sci. B: Polym. Phys., 42(19), 3654 (2004)

[12] Oiseth SK, Krozer A, Lausmaa J, Kasemo B, J. Appl. Polym. Sci., 92(5), 2833 (2004)

[13] Kim BS, Qiu JM, Wang JP, Taton TA, Nano Lett., 5, 1987 (2005)

[14] Heskins M, Guillet JE, J. Macromol. Sci. Chem., A2, 1441 (1968)

[15] Kohori F, Sakai K, Aoyagi T, Yokoyama M, Yamato M, Sakurai Y, Okano T, Colloids Surf. B., 16, 195 (1999)

[16] Wei H, Cheng SX, Zhang XZ, Zhuo RX, Prog.Polym. Sci., 34, 893 (2009)

[17] Riess G, Prog. Polym. Sci., 28, 1107 (2003)

[18] Lieske A, Jaeger W, Macromol. Chem. Phys., 199, 255 (1998)

[19] Szwarc M, J. Am. Chem. Soc., 78, 2656 (1956)

[20] Baskaran D, Muller AHE, Prog. Polym. Sci., 32, 173 (2007)

[21] Smith TJ, Mathias LJ, Polymer, 43(26), 7275 (2002)

[22] Storey RF, Baugh DW, Choate KR, Polymer, 40(11), 3083 (1999)

[23] Tang XD, Liang XC, Han NF, Chin. Chem. Lett., 20, 1353 (2009)

[24] Lee JM, Lee BH, Choe S, Polymer, 47(11), 3838 (2006)

[25] Li JB, Ren J, Cao Y, Yuan WZ, React. Funct.Polym., 69, 870 (2009)

[26] Qu TH, Wang AR, Yuan JF, Shi JH, Gao QY, Colloids Surf. B., 72, 94 (2009)

[27] Chen WQ, Wei H, Li SL, Feng J, Nie J, Zhang XZ, Zhuo RX, Polymer, 49(18), 3965 (2008)

[28] Qu TH, Wang AR, Yuan JF, Gao QY, J. Colloid Interface Sci., 336(2), 865 (2009)

[29] Qiao P, Niu QS, Wang ZB, Cao DP, Chem. Eng. J., 159(1-3), 257 (2010)

[30] Lee RS, Chen WH, Huang YT, Polymer, 51(25), 5942 (2010)

[31] Loh XJ, Tan YX, Li ZY, Teo LS, Goh SH, Li J, Biomaterials., 29, 2164 (2008)

[32] Wang WW, Yi Z, Jiang L, Dan Y, Polym. Mater. Sci.Eng., 26, 12 (2010)

[33] Li YY, Zhang XZ, Cheng H, Zhu JL, Li UN, Cheng SX, Zhuo RX, Nanotechnology., 18, 1 (2007)

[34] Kallay N, Tomasiae V, Zalac S, Chittofrati A, Colloid Polym. Sci., 272, 1576 (1994)

[35] Khougaz K, Gao ZS, Eisenberg A, Macromolecules, 27(22), 6341 (1994)

[36] Du BY, Mei AX, Yang Y, Zhang QF, Wang Q, Xu JT, Fan ZQ, Polymer, 51(15), 3493 (2010)

[37] You YZ, Hong CY, Wang WP, Lu WQ, Pan CY, Macromolecules, 37(26), 9761 (2004)

[38] Zhang XF, Zhou L, Zhang X, Dai H, J. Appl. Polym. Sci., 116(2), 1099 (2010)

[39] Wei H, Wu DQ, Li Q, Chang C, Zhou JP, Zhang XZ, Zhuo RX, J. Phys. Chem. C., 112, 15329 (2008)