Synthesis of Polyesters Containing Long Aliphatic Methylene Units by ADMET Polymerization and Synthesis of ABA-Triblock Copolymers by One-Pot End Modification and Subsequent Living Ring-Opening Polymerization.

The synthesis of high-molecular-weight ( M n up to 62,000 g/mol) polyesters has been achieved by acyclic diene metathesis (ADMET) polymerization of α,ω-dienes prepared from biobased bis(undec-10-enoate) and diols [ethylene glycol ( M1 ), propylene glycol ( M2 ), 1,9-nonanediol ( M3 ), 1,4-benzenedimethanol ( M4 ), and hydroquinone ( M5 )] using ruthenium-carbene catalysts. Replacement of the solvent during the ADMET polymerization was effective for obtainment of the high-molecular-weight polymers (expressed as P1 - P5 ). The melting temperatures ( T m ) in the resultant polyesters were dependent upon the diol (middle) segment employed, and the polymer prepared from M5 exceeded 100 °C (a T m value of 122.5 °C). The polymerization of M3 and M4 in the presence of 1,4- cis -diacetoxy-2-butene (DAB, as the chain transfer agent) afforded the telechelic polyesters [ P3(OAc) 2 and P4(OAc) 2 , respectively] containing acetoxy end groups exclusively. The resultant polymers containing hydroxy group termini [ P3(OH) 2 and P4(OH) 2 ], prepared by the selective deprotection of the acetoxy end groups, were treated with AlEt 3 followed by addition of ε-caprolactone to afford the ABA-type triblock copolymers exclusively, through a living ring-opening polymerization. The depolymerization (hydrolysis) under basic conditions (NaOH aqueous solution) of P3 was explored.