Xu Feng, Yan Ting-Ting, Luo Yan-Ling
Key Lab of Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi'an 710062, PR China.
J Nanosci Nanotechnol. 2012 Mar;12(3):2287-91. doi: 10.1166/jnn.2012.5705.
Thermo-sensitive amphiphilic block copolymers, poly(N-isopropylacrylamide)-block- poly(D,L-lactide) (PNIPAAm-b-PLA), were synthesized through a simple free radical copolymerization route based on a bifunctional initiator, 2,2'-azobis(2-methylpropion amidine) dihydrochloride (AMAD), followed by the ring-opening polymerization of D,L-lactide in the presence of Sn(Oct)2 catalyst. The Chemical structure characterization were conducted by means of 1H NMR, FT-IR, GPC. The amphiphilic PNIPAAm-b-PLA block copolymers could self-assemble into micelles with regularly spherical shape in an aqueous solution, with a TEM diameter range of 46-56 nm, DLS hydrodynamic diameter of 158-199 nm. This behavior depends on the environmental temperature, the hydrophobic interactions among PNIPAAm molecular chains, intermolecular hydrogen bonding between the PNIPAAm chains and water molecules as well as intramolecular hydrogen bonding between -CONH2 groups. The copolymers held a CMC from 5.50 to 6.17 mg L(-1) and LCST from 31.41-32.03 degrees C, being more or less affected by their compositions, PLA or PNIPAAm block length. The as-prepared PNIPAAm-b-PLA block polymers are anticipated to be applied as a potential candidate of drug release carriers.
通过基于双官能引发剂2,2'-偶氮二(2-甲基丙脒)二盐酸盐(AMAD)的简单自由基共聚路线，随后在Sn(Oct)2催化剂存在下进行D,L-丙交酯的开环聚合，合成了热敏性两亲嵌段共聚物聚(N-异丙基丙烯酰胺)-嵌段-聚(D,L-丙交酯)(PNIPAAm-b-PLA)。通过1H NMR、FT-IR、GPC进行化学结构表征。两亲性PNIPAAm-b-PLA嵌段共聚物在水溶液中可自组装成规则球形的胶束，TEM直径范围为46-56 nm，DLS流体动力学直径为158-199 nm。这种行为取决于环境温度、PNIPAAm分子链之间的疏水相互作用、PNIPAAm链与水分子之间的分子间氢键以及-CONH2基团之间的分子内氢键。共聚物的临界胶束浓度为5.50至6.17 mg L(-1)，最低临界溶液温度为31.41-32.03℃，或多或少受到其组成、PLA或PNIPAAm嵌段长度的影响。所制备的PNIPAAm-b-PLA嵌段聚合物有望作为药物释放载体的潜在候选物。
