Effect of Architecture on the Micellization Properties of Block Copolymers:  A₂B Miktoarm Stars vs AB Diblocks

Abstract

Light-scattering and viscometric results are presented from micellar solutions of (PI)2PS (I2S) and (PS)2PI (S2I) three-miktoarm stars and a PSPI (SI) diblock copolymer in n-decane. The influence of architecture on the micellization properties of simple graft copolymers is investigated by keeping the overall molecular weights and compositions of the samples constant. All samples formed spherical micelles in n-decane, a selective solvent for polyisoprene. Aggregation numbers were found to increase in the order I2S < S2I < SI. Hydrodynamic radii of the micelles increased in the same order. The thickness of the corona is determined by the length of the soluble blocks, which they were found to be stretched to almost the same extent in all cases. The area of the core−corona interface per copolymer chain, A c, depends on the architecture of the molecule, and it is larger in the case of I2S micelles. In the case of S2I, larger A c values were found compared to the SI reference sample, indicating that the PS arms are arranged in different ways in the two kinds of micelles. The presence of only one grafted chain per molecule can change considerably the micellar characteristics of complex block copolymers. A simple scaling theory is developed taking into account the free energy contributions from the core, the corona, and the interfacial region of the micelle in the different cases. Theoretical predictions agree qualitatively with the experimental results.

Synthesis of Amphiphilic Tadpole-Shaped Linear-Cyclic Diblock Copolymers via Ring-Opening Polymerization Directly Initiating from Cyclic Precursors and Their Application as Drug Nanocarriers

“…[1][2][3] It has been well-established that the topological structures and chemical composition of nonlinearshaped block copolymers can exhibit dramatic effects on the solution properties and self-assembling morphologies as compared with their linear counterpart. [4][5][6][7][8][9] It is worthy of noting that the developments of a variety of controlled radical polymerization techniques 10 such as atom transfer radical polymerization (ATRP), [11][12][13] reversible addition-fragmentation chain transfer (RAFT) polymerization, [14][15][16] and nitroxide-mediated polymerization (NMP) 17,18 have facilitated the synthesis of nonlinear-shaped polymers with varying chain architectures such as cyclic, 8,9,[19][20][21][22][23] (miktoarm) star, [24][25][26] star block copolymers, 27,28 comb, [29][30][31][32] sun-shaped, [33][34][35] H-shaped, [36][37][38] and θ-shaped 39,40 polymers. Among these nonlinear chain topologies, tadpole-shaped linearcyclic diblock copolymers [41]…”

Di-Stimuli Responsive Poly(<i>N</i>-Isopropylacrylamide-co-Diethylaminoethylmethacrylate) Copolymer: Synthesis, Characterization and Investigation of Aqueous Dispersion Properties

“…It is water-insoluble at neutral or alkaline pH, whereas below pH 6, it is soluble as a weak cationic polyelectrolyte due to protonation of tertiary amine residues. [35][36][37][38][39] Thus, we can expect that the copolymer, P(NIPAAm 85 -co-DEAEMA 140 ),…”

Dendrimers and miktoarm polymers based multivalent nanocarriers for efficient and targeted drug delivery

“…Other reports have also suggested that miktoarm polymers self-assemble differently from their linear counterparts. 144,145 Gou et al have reported the synthesis and drug loading of ibuprofenconjugated amphiphilic A 14 B 7 miktoarm stars composed of 14 PCL arms and 7 PEG arms with b-cyclodextrin (b-CD) as a core moiety. 146 These amphiphilic star polymers selfassembled into multimorphological aggregates in aqueous solution and showed higher drug loading capacity compared to the corresponding non-drug conjugated copolymers.…”