The electrostatic coassembly of a block copolymer polyelectrolyte poly(ethylene oxide-block-poly-(methacrylic acid), PEO 705 −PMAA 476 , and oppositely charged surfactant, N-dodecylpyridinium chloride (DPCl), has been investigated by a combination of isothermal titration calorimetry (ITC), spin-echo NMR spectroscopy, and timeresolved SAXS measurements. The study (i) confirms the conclusions drawn from our earlier study [Macromolecules 2012, 45, 6474] by scattering and microscopy techniques (i.e., the ITC curves can be interpreted using arguments consistent with conclusions of the earlier study) and (ii) yields new insight into the thermodynamic and kinetic behavior of the self-assembling system. The most important finding obtained by stopped-flow time-resolved SAXS measurements concerns the surprisingly high rate of processes of creation of structurally ordered cores of self-assembled surfactant−polyelectrolyte nanoparticles (<50 ms).

Poly(lactic-co-glycolic acid) (PLGA) were grafted to both ends of Pluronic ® F68 ((EO) 75 (PO) 30 (EO) 75 ) triblock copolymer to produce poly{(lactic acid) m -co-(glycolic acid) n }-b-poly(ethylene oxide) 75 -b-poly(propylene oxide) 30 -b-poly(ethylene oxide) 75 -b-poly{(lactic acid) m -co-(glycolic acid) n } (PLGA-F68-PLGA) pentablock copolymers. Molecular weights of PLGA blocks were controlled and five kinds of pentablock copolymers with different PLGA block lengths were synthesized using in-situ ring-opening polymerization of D,L-lactide and glycolide with tin(II) 2-ethylhexanoate (Sn(Oct) 2 ) catalyst. PLGA-F68-PLGA pentablock copolymers were characterized by ¹H-and ¹³C-NMR, GPC, and TGA. The numbers (2m, 2n) of repeating units for lactic acid and glycolic acid inside PLGA segments were obtained as (48, 17), (90, 23), (125, 40), (180, 59), and (246, 64), with 1 H-NMR measurement. From NMR data, the resultant molecular weights were determined in the range of 12,700-29,700, which were similar to those obtained from GPC. Polydispersity index was increased in the range of 1.32-1.91 as the content of PLGA blocks increased. TG and DTG thermograms showed discrete degradation traces for PLGA and F68 blocks, which indicate the weight fractions of PLGA blocks in pentablock copolymers can be calculated by TG profile and it is possible to remove PLGA block selectively. Hydrodynamic radius and radius of gyration of pentablock copolymer micelle were obtained in the range of 46-68 nm and 31-49 nm, respectively, in very dilute (i.e. 0.005 wt %) aqueous solution of THF:H 2 O = 10:90 by volume at 25 o C.