Self-Organizable Vesicular Columns Assembled from Polymers Dendronized with Semifluorinated Janus Dendrimers Act As Reverse Thermal Actuators

Abstract

The synthesis and structural analysis of polymers dendronized with self-assembling Janus dendrimers containing one fluorinated and one hydrogenated dendrons are reported. Janus dendrimers were attached to the polymer backbone both from the hydrogenated and from the fluorinated parts of the Janus dendrimer. Structural analysis of these dendronized polymers and of their precursors by a combination of differential scanning calorimetry, X-ray diffraction experiments on powder and oriented fibers, and electron density maps have demonstrated that in both cases the dendronized polymer consists of a vesicular columnar structure containing fluorinated alkyl groups on its periphery. This vesicular columnar structure is generated by a mechanism that involves the intramolecular assembly of the Janus dendrimers into tapered dendrons followed by the intramolecular self-assembly of the resulting dendronized polymer in a vesicular column. By contrast with conventional polymers dendronized with self-assembling tapered dendrons this new class of dendronized polymers acts as thermal actuators that decrease the length of the supramolecular column when the temperature is increased and therefore, are called reverse thermal actuators. A mechanism for this reversed process was proposed.

A fluorinated dendrimer achieves excellent gene transfection efficacy at extremely low nitrogen to phosphorus ratios

“…Therefore, fluorination can improve the affinity of polymers to cell membrane 27 and across the lipid bilayer of the cell membrane, as well as the endosome/lysosome membrane 28 , facilitating endosomal escape of the polymers. In addition, fluorinated polymers have low surface energy and prefer to associate with each other at low concentrations [29][30][31] , allowing the formation of polyplexes with nucleic acid at low nitrogen to phosphorus (N/P) ratios. Gene transfection at a low N/P ratio is essential to minimize the toxicity on the transfected cells.…”

Self-Assembly of Dendritic Dipeptides as a Model of Chiral Selection in Primitive Biological Systems

“…Their dendritic sheath modulates the reactivity and chemoselectivity of the polymeric backbone; for example, the thermal isomerization and electrocyclization of polyphenylacetylenes can be tuned depending on the presence and structure of dendritic side-chain substituents [93][94][95][96][97][98]. Moreover, the dendritic sheath generates completely new properties and functions: dendronized polyphenylacetylenes act as molecular gates [95] or as nanomechanical actuators that can displace objects by reversible extension and contraction [96,97]. These properties could potentially be further monitored by the presence of stereocenters in the dendronized polymer.…”

Fluorinated liquid crystalline dendrimers

“…One possibility could be to explore the effect on the supramolecular organization of dendrimers bearing fluorinated chains together with other moieties with different chemical compatibility such as oxyethylenic chains. Besides their self-assembly properties in bulk and segregation phenomena, these amphiphilic fluorinated LC dendrimers could also form well-defined supramolecular arrangements in other media such as water as observed for other fluorinated amphiphilic dendritic systems, [58] which could be appealing for other scientific fields such as nanoscience. Furthermore, their solubility in water could make these fluorinated amphiphilic systems potential vehicles for 19 F magnetic resonance image (MRI)-guided drug therapy.…”