A rigid, chiral, dendronized polymer with a thermally stable, right-handed helical conformation.
First- and second-generation dendronized polymethacrylates PG1 and PG2 carrying chiral 4-aminoproline-based dendrons were obtained on the half-gram scale in high molar masses (PG1: M(n)=5 x 10(6) g mol(-1), PG2: M(n)=1x10(6) g mol(-1)) by spontaneous (radical) polymerization of the corresponding vinyl macromonomers. NMR spectroscopic studies on PG2 together with its unprecedented high glass transition temperature (T(g)>200 degrees C, decomp) and structural parameters provided by atomistic MD simulations show this polymer to be rather rigid. Optical rotation and CD measurements revealed that PG2 adopts a helical conformation that remains unchanged over wide ranges of temperature and solvent polarity. It is also retained when the polymer is deprotected (and thus positively charged, de-PG2) at its terminal amino groups, by which the mass and steric demand of the dendrons is reduced by roughly 50 %. Molecular dynamics simulations on models of PG2 reveal its helical conformation to be right-handed, irrespective of backbone tacticity, and initial results also indicate that de-PG2 retains the right-handedness.
Zhang
Afang
A
Institute of Polymers, Department of Materials, ETH Zürich, Wolfgang-Pauli-Straase 10, Zürich, Switzerland. azhang@zzu.edu.cn
Rodríguez-Ropero
Francisco
F
Zanuy
David
D
Alemán
Carlos
C
Meijer
E W
EW
Schlüter
A Dieter
AD
D002942:Circular Dichroism; D050091:Dendrimers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D011108:Polymers / Q000737:chemistry*; D013053:Spectrophotometry; D013237:Stereoisomerism; D013696:Temperature
D050091:Dendrimers; D011108:Polymers