NatureWorks' invention is a ring-opening catalyst to make stereoregular
, high-temperature PLA copolymers starting with this mix of D and L lactic acids.
The poly(methacrylic acid) derived from the above PTrMA with a high optical activity was confirmed to be highly isotactic as expected and completely optically inactive, indicating that the stereoregular
polymer could not maintain the helical structure without the bulky triphenylmethyl groups.
PLA is crystallizable, such as poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), whereas atactic poly (D, L-lactide) (PDLLA), randomly copolymerized from racemic lactide, is amorphous while a certain amount of counit is incorporated.
M, Kawakami, Y, Synthesis of Stereoregular
and Optically Active Polysiloxanes Containing l,3-Dimelhyl-l,3-diphenyldisiloxane as a Constitutional Unit," Macromolecules, 33 (6) 1960-1963 (2000)
Because of the stereoregular
structure of the polymer, natural rubber crystallizes when strained or when stored at low temperatures.
Together with his wife, Professor Jacqueline Jozefowicz, Marcel discovered that random copolymers containing the basic chemical function groups of heparin in the right proportion, can also exhibit heparin-like properties -- contrary to conventional theory that supposes only highly organized, stereoregular
surfaces are capable of molecular recognition.
Structurally, cis-polyisoprene is a highly stereoregular
polymer with a -OH group at the [alpha]-terminal unit and three to four trans-units at the omega end of the molecule (i.
Because of their stereoregular
chain microstructure, optically pure polylactides, poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), are semicrystalline.
Z-N catalysts and metallocenes are each capable of making stereoregular
In Reynold's laboratory, he and his students are working on both the development of new two-dimensional NMR methods for characterization of complex organic compounds, and their applications to structure elucidation of natural products and stereoregular
polylactides result from polymerization of optically pure lactides.
The placement of the propylene residues is predominantly in a stereoregular