Formation of Polymeric Yolk/Shell Nanomaterial by Polymerization-Induced Self-Assembly and Reorganization

Abstract

Materials: Styrene (St) (Shanghai Chem. Co.) was washed with an aqueous solution of sodium hydroxide (5 wt %) three times and then washed with water until neutralization. After dried with anhydrous magnesium sulfate, St was distilled under reduced pressure. 4-Vinylpyridine (4VP, Acros, 96%) was dried over CaH 2 and then was distilled under reduced pressure prior to use. The 2,2'-azobisisobutyronitrile (AIBN) was purified by recrystallization from ethanol. All other reagents with analytical grade were used as received. Synthesis of S-1-dodecyl-S-(α, 'α -dimethyl-'' α -acetic acid) trithiocarbonate (TC): TC was synthesized in yield of 78.4% according to reference 1. 1 HNMR, δ(TMS, ppm): 0.90 (t, 3H, -CH 3 ), 1.37-1.47 (m, 20H, -(CH 2 ) 10 -), 1.75 (s, 6H, 2-CH 3 ), 3.42 (t, 2H, -CH 2 S), 13.05 (s, 1H, -COOH). Preparation of TC-terminated poly(4-vinylpyridine) (P4VP-TC):The general procedure is as follows. TC (36 mg, 0.1 mmol), 4VP (2.12 g, 20 mmol), isopropanol (2 mL) and AIBN (2 mg, 0.01 mmol) were added into a 10 mL polymerization tube with a magnetic bar. After three freeze-evacuate-thaw cycles, the tube was sealed under high vacuum, and then the sealed tube was placed in an oil bath at 80 o C while stirring. After 6 h, the tube was cooled to room temperature with ice-water, and then the tube was opened. The polymer was precipitated by pouring a polymer solution in

Polymerization-induced self-assembly of block copolymer nanoparticles via RAFT non-aqueous dispersion polymerization

“…Pan and co-workers [28,[52][53][54][55][56][57] have utilized a trithiocarbonate-based chain transfer agent (DDMAT, see Figure 2a) to prepare a range of poly(4-vinylpyridine) (P4VP) macro-CTAs for the subsequent dispersion polymerization of styrene in methanol. The resulting poly(4-vinylpyridine)-polystyrene (P4VP-PS) nanoparticles formed a wide range of copolymer morphologies ( Figure 3 andFigure 4) [28,[52][53][54][55][56][57].…”

“…Pan and co-workers [28,[52][53][54][55][56][57] have utilized a trithiocarbonate-based chain transfer agent (DDMAT, see Figure 2a) to prepare a range of poly(4-vinylpyridine) (P4VP) macro-CTAs for the subsequent dispersion polymerization of styrene in methanol. The resulting poly(4-vinylpyridine)-polystyrene (P4VP-PS) nanoparticles formed a wide range of copolymer morphologies ( Figure 3 andFigure 4) [28,[52][53][54][55][56][57]. Like the analogous RAFT aqueous dispersion formulations [17,25,58], purely spherical, worm-like or vesicular morphologies could be targeted by tuning the block composition, which is consistent with the geometric packing argument for surfactant selfassembly introduced by Israelachvili and co-workers [6], and subsequently extended to block copolymer self-assembly by Antonietti and Förster [7].…”

“…This enabled enhanced fluorescence properties of the resulting vesicles upon exposure to UV radiation as a result of photoisomerization of the SPMA repeat units. In addition to spheres, worms and vesicles, P4VP-PS block copolymer nanoparticles have been used to access more complex structures such as the so-called 'yolk/shell' morphology ( Figure 4d) [53]. In this case, PS homopolymer chains were present during the PISA synthesis of P4VP-PS vesicles.…”

Characterization of Diblock Copolymer Order-Order Transitions in Semidilute Aqueous Solution Using Fluorescence Correlation Spectroscopy

“…[14][15][16] This versatile approach has enabled spherical, worm-like or vesicular copolymer morphologies to be generated in concentrated solution. [ 11,[17][18][19][20][21][22][23][24][25][26] Such a nonionic PGMA-PHPMA diblock copolymer exhibits a thermoreversibleThe temperature and pH-dependent diffusion of poly(glycerol monomethacrylate)-blockpoly(2-hydroxypropyl methacrylate) nanoparticles prepared via polymerization-induced self-assembly in water is characterized using fl uorescence correlation spectroscopy (FCS). Lowering the solution temperature or raising the solution pH induces a worm-to-sphere transition and hence an increase in diffusion coeffi cient by a factor of between four and eight.…”

“…[14][15][16] This versatile approach has enabled spherical, worm-like or vesicular copolymer morphologies to be generated in concentrated solution. [ 11,[17][18][19][20][21][22][23][24][25][26] Such a nonionic PGMA-PHPMA diblock copolymer exhibits a thermoreversible…”