Synthesis and characterization of amphiphilic cationic symmetrical ABCBA pentablock terpolymer networks: Effect of hydrophobic content

Abstract

Group transfer polymerization was employed for the preparation of six amphiphilic terpolymer networks comprising the hydrophilic, pH‐responsive 2‐(dimethylamino)ethyl methacrylate (DMAEMA), the neutral hydrophilic methoxy hexa(ethylene glycol) methacrylate (HEGMA), and the hydrophobic n‐butyl methacrylate (BuMA). 1,4‐Bis(methoxytrimethylsiloxymethylene)cyclohexane was used as a bifunctional initiator, whereas ethylene glycol dimethacrylate served as the crosslinker to interconnect the linear terpolymer precursors to three‐dimensional terpolymer network structures. Five of the terpolymer networks were model, with linear chains between crosslinks of precise length. Four of the five model networks were based on ABCBA pentablock terpolymers with theoretical structure DMAEMA5‐b‐BuMAn/2‐b‐HEGMA10‐b‐BuMAn/2‐b‐DMAEMA5 with n values equal to 5, 10, 20, and 30. The model network based on the equimolar statistical terpolymer and the nonmodel randomly crosslinked terpolymer network were also prepared. The molecular weights and compositions of the linear pentablock terpolymer precursors to the networks were found to be close to the theoretically expected, while the network sol fractions were found to be relatively low. The degrees of swelling of the networks in water were found to decrease with increasing the hydrophobic content, whereas those in THF exhibited the opposite trend. Small‐angle neutron scattering in deuterium oxide indicated structural organization in the most hydrophobic pentablock terpolymer networks. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4420–4432, 2008

Stepped association of comb‐like and stimuli‐responsive graft chitosan copolymer synthesized using ATRP and active ester conjugation methods

“…In the latter, three different association states were observed, depending on pH due to relatively large difference p K α between the P2VP and PDMAEMA blocks. As an important representative of the pH‐stimuli micelle component, PDMAEMA has also been included into many novel copolymers recently 34–38. By forming nanospheres or micelles via self‐assembly, CS graft copolymers have attracted abroad interests because of their potentials in biomedical applications 39, 40.…”

Microfluidically fabricated pH-responsive anionic amphiphilic microgels for drug release

“…This was expected and similarly observed in macrogels. 34,35,[45][46][47][48][49][50] pK a s of amphiphilic microgels…”

Synthesis of PS-b-PPOA-b-PS triblock copolymer via sequential free radical polymerization and ATRP

“…The sequential feeding method means that block copolymer can be obtained by the sequential feeding of different monomers under the same kind of living polymerization mechanism such as anionic, cationic, group transfer, and living radical polymerization . The site transformation approach refers to synthesizing the block copolymers via different polymerization mechanisms, for which bi‐ and multifunctional initiators have been designed and prepared for attaining different polymerization mechanism demands of the monomers with different chemical structures . By this way, end‐functionalized macroinitiator was first prepared and subsequently employed to initiate the polymerization of the second monomer by another polymerization mechanism.…”

“…the monomers with different chemical structures. [30][31][32][33][34][35] By this way, end-functionalized macroinitiator was first prepared and subsequently employed to initiate the polymerization of the second monomer by another polymerization mechanism. In principle, any block copolymer not easy for synthesis by single polymerization mechanism could be designed and synthesized by this strategy.…”