2 research outputs found
Diversity-Oriented Polymerization: One-Shot Synthesis of Library of Graft and Dendronized Polymers by Cu-Catalyzed Multicomponent Polymerization
Graft
and dendronized polymers have attracted much attention in
the polymer community, and there have been significant efforts to
develop better synthetic methods. Herein, we report the highly efficient
synthesis of graft and dendronized polymers by using Cu-catalyzed
multicomponent polymerization (MCP). Based on diversity-oriented synthesis,
we prepared a library of various graft and dendronized polymers from
combinations of three types of monomers (mono-functionalized alkynes,
bis-sulfonyl azides, and diamines/diols) that are bench stable and
readily accessible. After reaction optimization, 54 samples of high-molecular-weight
graft and dendronized polymers were prepared, the MCP method allowing
simultaneous manipulation of the structures of both the main chains
and the side chains. Moreover, because of the severe steric hindrance
of the side chains, these polymers adopted extended conformations,
as shown by the large shape parameter in solution. Also, the extended
morphology of the single polymer chains was directly visualized by
atomic force microscopy and transmission electron microscopy in the
solid state. Most importantly, this diversity-oriented polymerization
became possible because of highly step-economical and efficient one-step
MCP, paving the way toward the easily tunable synthesis of graft and
dendronized polymers
Structure and Dynamics of Dendronized Polymer Solutions: Gaussian Coil or Macromolecular Rod?
We
investigate the conformation of well-defined dendronized polymers
(denpols) based on poly(norborene) (PNB) and poly(<i>endo</i>-tricycle[4.2.2.0]deca-3,9-diene) (PTD) backbones employing static
and dynamic light scattering. Their synthesis by ring-opening metathesis
polymerization (ROMP) led to fully grafted and high molecular weight
denpols with narrow polydispersity. In dilute solutions, the persistence
lengths were estimated by static (radius of gyration) and dynamic
(translational diffusion) chain conformational properties of the denpols
and were compared to their homologue precursor PNB. The conformation
of denpols with a third generation side dendron conforms to a semiflexible
chain with a persistence length of about 6–8 nm, virtually
independent of the contour length. In the semidilute regime, the thermodynamics
and cooperative diffusion of denpols resemble the behavior of the
precursor solutions as described by the scaling theory of flexible
polymers above the crossover concentration. The assumption of extremely
high chain rigidity for this class of polymers is clearly not supported,
at least for the third generation dendron