ma7b00747_si_001.pdf (3.69 MB)
Dendronized Polymers with Ureidopyrimidinone Groups: An Efficient Strategy To Tailor Intermolecular Interactions, Rheology, and Fracture
journal contribution
posted on 2017-06-19, 18:52 authored by Leon F. Scherz, Salvatore Costanzo, Qian Huang, A. Dieter Schlüter, Dimitris VlassopoulosA library of poly(methyl
methacrylate)-based dendronized polymers
with generation numbers g = 1–3 was prepared,
which contain different degrees of dendritic substitution (0–50%)
with strongly hydrogen bonding 2-ureido-4[1H]pyrimidinone
(UPy) moieties at their respective g = 1 levels.
Our rheological and thermal studies demonstrate that the strong intermolecular
UPy interactions are suppressed for g = 2 and essentially
eliminated for g = 3. Focusing on samples with short
backbone degrees of polymerization (Pn ≈ 40), the linear viscoelastic response alters from liquid-like
in the absence of UPy to gel-like with ever increasing moduli as the
UPy content increases. Nonlinear rheological measurements indicate
a transition from ductile to brittle behavior and, in parallel, a
transition from shear strain thinning to shear strain hardening. This
unique behavior makes UPy-DPs promising candidates for the design
of new functional materials.