摘要
用单氨基聚乙二醇(m PEG-NH2)引发ε-三氟乙酰基-L-赖氨酸-N-羧酸酐(Lys(TFA)-NCA)开环聚合,得到了聚乙二醇-b-聚(ε-三氟乙酰基-L-赖氨酸)(PEG-b-PTLL)两嵌段共聚物.将PTLL链段末端的NH2与2-溴异丁酰溴反应得到了大分子引发剂,通过原子转移自由基聚合(ATRP)的方法分别分别引发苯乙烯(St)和N-异丙基丙烯酰胺(NIPAM)聚合,制备了结构明确、聚合度可控的聚乙二醇-b-聚(ε-三氟乙酰基-L-赖氨酸)-b-聚苯乙烯(PEG-b-PTLL-b-PS)和聚乙二醇-b-聚(ε-三氟乙酰基-L-赖氨酸)-b-聚(N-异丙基丙烯酰胺)(PEG-b-PTLL-b-PNIPAM)三嵌段杂化共聚肽.将PEG-b-PTLL-b-PNIPAM去保护后得到温度和p H响应三嵌段共聚物;将PEG-b-PTLL-b-PS去保护后得到p H响应的两亲性三嵌段共聚物.研究了PEG45-b-PLL106-b-PS20在混合溶剂H2O/DMF中的p H诱导胶束化行为.TEM结果表明,当水溶液p H小于PLL的p Ka时,PEG45-bPLL106-b-PS20形成球状胶束,当水溶液p H大于PLL的p Ka时,PLL转变成α-螺旋,PEG45-b-PLL106-b-PS20组装成盘状胶束.
Two polylysine-containing ABC-type triblock hybrid copolymers, poly (ethylene glycol)-b-poly- (TFA-L-lysine) -b-poly ( styrene ) ( PEG-b-PTLL-b-PS ) and poly ( ethylene glycol ) -b-poly ( TFA-L-lysine ) -b- poly(N-isopropylacrylamide) (PEG-b-PTLL-b-PNIPAM), were successfully synthesized via sequential ring- opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The diblock precursor, PEG- b-PTLL-NH2 was prepared via the ROP of ^-trifluoroacetyl-L-lysine N-carboxyanhydride (Lys (TFA)-NCA) with amino-terminated PEG as the initiator. Then the diblock was converted to a macromolecular initiator (PEG-b-PTLL-Br) through the amidation with 2-bromoisobutyryl bromide in the presence of triethylamine (TEA) and 4-dimethylaminopyridine (DMAP). Two series of triblock hybrid eopolymers, PEG-b-PTLL-b-PS and PEG-b-PTLL-b-PNIPAM, were obtained via ATRP under appropriate conditions. The GPC and NMR characterizations verified the successful preparation of triblock copolymers. The above results showed that the DP of each block can be adjusted by molecular design and variation of reaction time. Considering the rich amido groups in both backbone and side chain of PTLL block, we applied a relatively high amount of Cu (I) salts and ligand for effective activation and performed the ATRP in high-polarity organic solvent to overcome the effects of amide groups. Moreover, the self-assembly of amphiphilic PEG-b-PLL-b-PS was explored in mixture solvents at different pH values. It was found that the morphologies of resultant micelles depended on pH values in the water/DMF mixed solvent. When pH 〈 pKa ( ca. 10.5 ) , the PEG45-b-PLL106-b-PS20 triblock formed spherical micelles. When pH 〉 pKa, the PEG45-b-PLL106-b-PS20 triblock formed disk-like micelles.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2015年第8期982-988,共7页
Acta Polymerica Sinica
基金
国家自然科学基金(基金号51303187)资助项目