A facile strategy for manipulating micellar size and morphology through intramolecular cross-linking of amphiphilic block copolymers. Issue 23 (5th June 2017)

• Record Type: Journal Article
• Authors: Tanaka, Ryoto; Watanabe, Kodai; Yamamoto, Takuya; Tajima, Kenji; Isono, Takuya; Satoh, Toshifumi
• Is Part Of: Polymer chemistry. Volume 8:Issue 23(2017)
• Page Start: 3647
• Page End: 3656
• Publication Date: 2017-06-05
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/c7py00646b
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : The effect of intramolecular cross-linking on aqueous self-assembly behavior was systematically investigated based on an amphiphilic block copolymer system. Abstract : The effect of intramolecular cross-linking in an amphiphilic block copolymer (BCP) system was systematically investigated in terms of its thermal properties, critical micelle concentration (CMC), and aqueous self-assembly. A series of linear BCPs consisting of poly(ethylene glycol) (PEG) as a hydrophilic block and poly(ε-caprolactone- co -7-allyloxepan-2-one) (P(CL- co -ACL)) as a hydrophobic block were prepared by the ring-opening copolymerization of ε-caprolactone (CL) and 7-allyloxepan-2-one (ACL) using poly(ethylene glycol)monomethyl ether as an initiator. The intramolecular olefin metathesis reaction in the P(CL- co -ACL) block was subsequently carried out under various conditions to prepare the cross-linked BCPs with different degrees of cross-linking. The thermal analysis confirmed that the linear P(CL- co -ACL) block was found to crystallize, while the cross-linked one showed no crystallinity. In addition, glass transition temperature of the P(CL- co -ACL) block increased upon cross-linking. On the other hand, the intramolecular cross-linking had no significant influence on the CMC. The self-assembled micelles were prepared from the obtained BCPs and their size and morphology were investigated. For the BCPs with relatively short PEG chains, the micellar size decreased from 36.6 nm to 16.7 nm as the degree of cross-linking of the P(CL- co -ACL) block increased. On the other hand, the BCPs with relatively long PEG chains showed a change in the micellar morphology from spherical micelles to short worm and large compound micelles upon cross-linking.