Beyond Simple AB Diblock Copolymers: Application of Bifunctional and Trifunctional RAFT Agents to PISA in Water

Abstract

The influence of the macromolecular reversible addition-fragmentation chain transfer (macro-RAFT) agent architecture on the morphology of the self-assemblies obtained by aqueous RAFT dispersion polymerization in polymerization-induced self-assembly (PISA) is studied by comparing amphiphilic AB diblock, (AB) triblock, and triarm star-shaped (AB) copolymers, constituted of N,N-dimethylacrylamide (DMAc = A) and diacetone acrylamide (DAAm = B). Symmetrical triarm (AB) copolymers could be synthesized for the first time in a PISA process. Spheres and higher order morphologies, such as worms or vesicles, could be obtained for all types of architectures and the parameters that determine their formation have been studied. In particular, we found that the total DP of the PDMAc and the PDAAm segments, i.e., the same overall molar mass, at the same M (PDMAc)/M (PDAAm) ratio, rather than the individual length of the arms determined the morphologies for the linear (AB) and star shaped (AB) copolymers obtained by using the bi- and trifunctional macro-RAFT agents.

Loop-stabilized BAB triblock copolymer morphologies by PISA in water

“…The control over the polymerization was investigated by SEC, and as reported in Table 1 and Figure 1). As previously observed for diblock, 43 triblock 30 and star copolymers 16 an increase of the sphere diameter with the hydrophobic block length was observed by TEM and DLS measurements. However, no higher order morphologies, e.g.…”

“…35 They were used in the solution polymerization of DMAc in DMF in presence of AIBN as an initiator. 16,40,41 The purified polymers were characterized by 1 H NMR and SEC (Table S1). In comparable polymerization conditions, the kinetics were similar for both RAFT agents and relatively high monomer conversions (~75%) were reached after 2.2 h ( Figure S1A and B).…”

“…1,3,6,7 Another important parameter, that has received much less attention so far in PISA, should be the macromolecular architecture of the polymer chains. Hitherto there are only few reports in the literature comparing notably linear chains with stars or branched structures, 13,14 diblocks with triblocks or multiblocks [15][16][17][18][19][20][21][22] in PISA. Nonetheless, most of the studied systems are currently based on simple AB diblock copolymers, where A is the solvophilic, stabilizer block, and B is the solvophobic block.…”

Probing the mechanism for hydrogel-based stasis induction in human pluripotent stem cells: is the chemical functionality of the hydrogel important?

“…This new synthetic hydrogel comprises highly anisotropic worm-like particles formed by the self-assembly of an amphiphilic poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) [PGMA-PHPMA] diblock copolymer. 18,19 The worms are formed directly in aqueous solution during the synthesis of the diblock copolymer chains via a highly efficient and convenient process known as RAFT aqueous dispersion polymerization, [20][21][22][23][24][25][26][27][28][29][30][31][32] which is an example of polymerization-induced self-assembly (PISA). [33][34][35][36][37][38] Gelation is believed to be the result of multiple inter-worm contacts, which leads to local arrest of translational diffusion.…”

Polymerization‐Induced Self‐Assembly

“…An alternative way to tune particle morphology is proposed by Zetterlund and co‐workers by conducting PISA under different CO 2 pressures using a CO 2 ‐responsive macroRAFT agent stabilizer . The group of Rieger and Stoffelbach used standard experimental conditions, but tuned the particle morphology by using multifunctional RAFT agents generating amphiphilic triblock and star copolymers. They rationally correlated the observed particle morphology with the macromolecular characteristics.…”