Novel thermoresponsive fluorinated double-hydrophilic poly{[N-(2,2-difluoroethyl)acrylamide]-b-[N-(2-fluoroethyl)acrylamide]} block copolymers

作者：Bak Jae Min; Lee Hyung il^*

来源：Journal of Polymer Science Part A: Polymer Chemistry , 2013, 51(9): 1976-1982.

DOI：10.1002/pola.26578

• diblock copolymers
• double-hydrophilic
• fluorinated polymer
• LCST
• reversible addition fragmentation chain transfer (RAFT)
• stimuli-sensitive polymers
• thermoresponsive

Novel thermoresponsive double-hydrophilic fluorinated block copolymers were successfully synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly[N-(2,2-difluoroethyl)acrylamide] (P2F) was synthesized via RAFT polymerization of N-(2,2-difluoroethyl)acrylamide (M2F) using 2-dodecylsulfanylthiocarbonylsulfanyl-2-methylpropionic acid (DMP) as the chain transfer agent (CTA) and 2,2-azobisisobutyronitrile (AIBN) as the initiator. The resulting P2F macroCTA was further chain extended with N-(2-fluoroethyl)acrylamide (M1F) to yield poly{[N-(2,2-difluoroethyl)acrylamide]-b-[N-(2-fluoroethyl)acrylamide]} (P2F-b-P1F) block copolymers with different lengths of the P1F block. Molecular weight and molecular weight distribution were determined by gel permeation chromatography. The average molecular weight (Mn) of the resulting polymers ranged from 2.9 x 104 to 5.8 x 104 depending on the length of the P1F block. The molecular weight distribution was low (Mw/Mn = 1.111.19). Turbidimetry by UV-Visble (UV-Vis) spectroscopy, dynamic light scattering, and in situ temperature-dependent 1H NMR measurements demonstrated that the P2F block underwent a thermal transition from hydrophilic to hydrophobic, which in turn induced self-assembly from unimers to aggregates. Transmission electron microscopy studies demonstrated that polymeric aggregates formed from an aqueous solution of P2F-b-P1F at 60 degrees C were disrupted by cooling down to 20 degrees C and regenerated by heating to 60 degrees C. Temperature-triggered release of a model hydrophobic drug, coumarin 102, was also demonstrated.

• 出版日期2013-5-1