A ternary rare earth metal coordination catalyst was used for terpolymerization of carbon dioxide

propylene oxide (PO) and maleic anhydride (MA).The chemical structure as well as MA content in the terpolymer was determined by FTIR and 1H-NMR spectra.The terpolymer was denoted as PPCMA

it showed 4.1% MA content when the MA loading in the comonomer (weight ratio of MA to PO

MA/PO) was 3/97.The glass transition temperature of this PPCMA was 13.4 ℃

and the temperature at 5 wt% loss of thermal decomposition was 217 ℃

it also showed tensile strength of 2.88 MPa with elongation at break of 1669%.Therefore

this PPCMA can act as toughening material at room temperature.It was used to solve the brittleness of blend from poly(propylene carbonate) (PPC) and poly(3-hydroxylbutyrate) (PHB).When 10 wt% of PPCMA was added into blend of PPC/PHB

it showed tensile strength of 18.2 MPa

while elongation at break increased to 85%

a 4.25 times increase compared with PPC/PHB sample

therefore

PPCMA can significantly improve the brittleness of PPC/PHB blends.The polarized optical microscopy (POM) image indicated that PPC itself did not show significant influence on the crystallization of PHB

mainly due to their immiscibility.When PPCMA was added into PPC/PHB blends

the number of spherulites increased significantly

while the size of nascent spherulites of PHB became smaller

and developed much fast than that without PPCMA addition

indicating that PPCMA may be a special nuclear agent

though it was an amorphous polymer.The reason may lie in that the soft segment of PPCMA chain may enhance the hydrogen interaction between the hydroxyl group of PHB and the carbonyl group in PPC

which may be beneficial to reduce the spherulite of PHB.