Organic Nanoparticles Whose Size and Rigidity Are Finely Tuned by Cross-Linking the End Groups of Dendrimers

Abstract

Dendrimers with molecular weights ranging from ca. 2700 to 11 000 and from 16 to 64 homoallyl ether end groups were cross-linked using the Grubbs ring-closing metathesis reaction. A combination of SEC, MALDI-TOF-MS, and AFM were used to characterize the cross-linked nanoparticles. The data suggest a significant decrease in volume with cross-linking and a concomitant increase in rigidity, both of which can be controlled independently with a fair degree of precision.

The Olefin Metathesis Reactions in Dendrimers

“…For instance, a third generation Fréchet-type dendrimer containing 24 allyl ether end-groups was synthesized by the Zimmerman group, cross-linked using the ring-closing metathesis (RCM) reaction, and the core was removed hydrolytically without significant fragmentation [31,32]. The results are analogous to those previously reported for homoallyl ether dendrimers suggesting that the less readily available homoallyl ether dendrimers can be replaced by their allyl ethers analogues [33].…”

Conjugated Polymer Nanoparticles via Intramolecular Crosslinking of Dendrimeric Precursors

“…Chemical or physical crosslinking of dendrimers has attracted a lot of attention recently with focus on both inter-and intramolecular crosslinking. [12,13] For example, the placement of functional groups at the termini or in well-defined segments can ultimately dictate their properties and provide highly controlled macromolecular systems. [14] In the present work, we have used a third generation carbazole-terminated Fréchet-type polybenzylether dendrimers (G3-D), which have been synthesized in our group.…”

“…Thus, the results show seemingly contradictory data in terms of change in height, while crosslinking results in the formation of a more rigid structure and a lower radius of gyration R g value, owing to the compact nature of the crosslinked dendrimer. [12] To delineate the effect of rigidity and dendrimer nanoparticle-substrate interaction, we also studied the uncrosslinked and intramolecularly crosslinked dendrimer on a low free-energy silanized silicon wafer as compared to the high free-energy surface of mica. The dendrimers were spin-coated following similar protocols and using exactly the same solution concentrations as before.…”

Synthesis of Core‐Crosslinked Nanoparticles with Controlled Cylindrical Shape and Narrowly‐Dispersed Size via Core‐Shell Brush Block Copolymer Templates

“…[1,2] As an interesting class of nanoobject, crosslinked polymeric core-shell nanoparticles with well-defined macromolecular architectures have been synthesized, typically by convergent synthetic polymer and organic chemistries using either core-shell dendrimers or block copolymer micelles as templates. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Their shape and size control, however, remains challenging. Such crosslinked nanoparticles derived from core-shell dendrimers generally have globular shapes with relatively small dimensions, of several nanometers.…”

“…Such crosslinked nanoparticles derived from core-shell dendrimers generally have globular shapes with relatively small dimensions, of several nanometers. [4][5][6][7] When formed by self assembly, block copolymer micelles have abundant morphologies with dimensions varied from tens to hundreds of nanometers and, therefore, can be considered as versatile templates. Although such a self-assembly strategy offers core-shell nanostructures with spherical, [10][11][12]21,22] cylindrical, [13][14][15][16]22] disk, [17] toroidal, [18,19] and other shapes, [23][24][25] it suffers from limited size control.…”