New Morphologies and Phase Transitions of Rod–Coil Dendritic–Linear Block Copolymers Depending on Dendron Generation and Preparation Procedure

Abstract

Amphiphilic rod−coil dendritic−linear block copolymers PEG(G m )-b-PMPCS (where m is the number of dendron generation, and m = 1, 2, 3) composed of a semirigid Percec-type dendron with hydrophilic poly(ethylene glycol) (PEG) tails and a rodlike mesogen-jacketed liquid crystalline polymer, poly{2,5-bis[(4′methoxy-phenyl)oxycarbonyl]styrene} (PMPCS), were successfully prepared. The self-assembled structures undergo a transition from vesicles through large compound vesicles (LCVs) to short cylindrical micelles with increasing dendron generation. PEG(G 2 )-b-PMPCS forms stable LCVs with porous surfaces of a narrow size distribution in a mixed solvent of tetrahydrofuran and water. The formation mechanism of the supramolecular structure with nano-and microsized scales is studied through changing the rate of water addition. It is composed of two steps: morphological transformation and vesicles fusion or differentiation. Vesicles are precursors for LCVs regardless of what the initial morphology is. However, the final LCV structures are different. Slow addition of water produces spherical LCVs, while those formed during fast water addition are irregular (like deformed spherical) LCVs.

Spherical Compound Micelles with Lamellar Stripes Self‐Assembled from Star Liquid Crystalline Diblock Copolymers in Solution

“…Recently, Fan and co‐workers studied the self‐assembly behavior of a series of amphiphilic dendritic‐linear block copolymers with a semirigid LC linear block in solution. They found that the self‐assembled structures undergo a transition from vesicles through large compound vesicles with porous surfaces to short cylindrical micelles mixed with loops as the dendron generation increases . However, ordered mesostructures from LC groups have not been pointed out in their work.…”

Responsive Linear‐Dendritic Block Copolymers

“…Stupp and co‐workers previously reported the tendency of dendron‐rod‐coil molecules to self‐assemble into one‐dimensional nanostructures, which may be of great interest in the charge transfer process of devices processed from these materials . More recently, Shen, Fan, and co‐workers have described rod‐coil LDBCs based on poly(benzyl ether) dendrons having peripheral PEG chains and a rod‐like mesogen‐jacketed liquid crystalline polymer, and explored the self‐assembly properties in solution in the search of large compound vesicles as potential templates to prepare mesoporous materials …”

A Novel Branched–Hyperbranched Block Polyolefin Produced via Chain Shuttling Polymerization from Ethylene Alone

“…Recently, a large number of architecturally block polymers such as dendritic-linear block polymers, hyperbranched-linear polymers and star-linear polymers were produced via ''living''=controlled polymerization and coupling block polymers techniques [20][21][22][23][24] . However, in all aforementioned strategies, low efficiency of ''living''= controlled polymerization techniques for a catalyst molecule only initiating a polymer chain, tedious polymer functionalization, purification and separation procedures leading to high costs for commercial utility.…”

“…As shown in Fig. 1, homogeneous single site catalyst f2,6-i Pr 2 -C 6 H 3 N=C(CH 3 )-(CH 3 )C=N-i Pr 2 -C 6 H 2 g NiBr 2 (CatA) produces hyperbranched polyethylene containing more than 100 branches=1000 carbons at one ethylene atmosphere and 20 C. Meanwhile, f2,6-Me 2 -C 6 H 3 N = C(CH 3 )-(CH 3 )C = N-Me 2 -C 6 H 2 gNiBr 2 (CatB) yields branched polyethylene with medium branching degree at the same conditions [20] . Besides the chain walking polymerization techniques, chain shuttling polymerization techniques are useful means of producing multiblock polymer which containing two or more chain architectures [28][29][30][31][32] .…”