2 research outputs found
Polyphosphoramidates That Undergo Acid-Triggered Backbone Degradation
The
direct and facile synthesis of polyphosphoramidates (PPAs)
with acid-labile phosphoramidate backbone linkages are reported, together
with demonstration of their hydrolytic degradability, evaluated under
acidic conditions. The introduction of acid-labile linkages along
the polymer backbone led to rapid degradation of the polymer backbone
dependent upon the environmental stimuli. An oxazaphospholidine monomer
bearing a phosphoramidate linkage was designed and synthesized to
afford the PPAs via organobase-catalyzed ring-opening polymerization
in a controlled manner. The hydrolytic degradation of the PPAs was
studied, revealing breakdown of the polymer backbone through cleavage
of the phosphoramidate linkages under acidic conditions
Two-Dimensional Controlled Syntheses of Polypeptide Molecular Brushes via <i>N</i>‑Carboxyanhydride Ring-Opening Polymerization and Ring-Opening Metathesis Polymerization
Well-defined molecular
brushes bearing polypeptides as side chains
were prepared by a “grafting through” synthetic strategy
with two-dimensional control over the brush molecular architectures.
By integrating <i>N</i>-carboxyanhydride ring-opening polymerizations
(NCA ROPs) and ring-opening metathesis polymerizations (ROMPs), desirable
segment lengths of polypeptide side chains and polynorbornene brush
backbones were independently constructed in controlled manners. The
N<sub>2</sub> flow accelerated NCA ROP was utilized to prepare polypeptide
macromonomers with different lengths initiated from a norbornene-based
primary amine, and those macromonomers were then polymerized via ROMP.
It was found that a mixture of dichloromethane and an ionic liquid
were required as the solvent system to allow for construction of molecular
brush polymers having densely-grafted peptide chains emanating from
a polynorbornene backbone, polyÂ(norbornene-<i>graft</i>-polyÂ(β-benzyl-l-aspartate)) (PÂ(NB-<i>g</i>-PBLA)). Highly efficient
postpolymerization modification was achieved by aminolysis of PBLA
side chains for facile installment of functional moieties onto the
molecular brushes