We investigated the ring opening polymerization (ROP) of di- and tri-ethylene glycol monomethyl ether functionalized L-glutamate

N

-carboxyanhydrides (NCAs) using hexamethyldisilazane (HMDS) as primary initiator and 1

5

7-triazabicyclo-[4.4.0]dec-5-ene (TBD) as co-initiator. The binary initiator system afforded a living ROP for these pegylated NCAs

and a series of homopolypeptides with controlled molecular weight (MW) and low polydispersity were obtained. We then systematically studied the helical content and clouding point (CP) dependence on polypeptide MW using circular dichroism (CD) spectroscopy and turbidity measurements

respectively. We found that the helical content of both homopolypeptides increased with MW

but the triethylene glycol functionalized poly-L-glutamate (poly-L-EG

3

Glu) intended to form more stable

α

-helical structure than diethylene glycol functionalized counterpart (poly-L-EG

2

Glu) at similar MW. Accordingly

the CP of poly-L-EG

2

Glu with known end group has strong dependence on its helical content

which is essentially determined by MW. Our results suggested that the thermal responsive properties of these unique pegylated poly-L-glutamates not only rely on their chemical structure but also on their secondary structures

which is different from conventional thermal responsive polymers.