The Synthesis Of Sustainable Polymers Of α-Oinene And δ-Valerolactone

In recent years,sustainable polymers have attracted more and more researchers’attention because of their more conformity to the concept of human green chemistry.On the one hand,people seek natural renewable resources as raw materials for monomers,and on the otherhand,they design and synthesize biodegradable polymers in the short-term.In this paper,α-pinene,which is rich in natural yield,is selected as a raw material,which is quantitatively converted into pinocarvone for polymerization by one-step photo-oxidation reaction.The difference from previous studies is that we found that only selective vinyl addition occurred in the polymerization process using Lewis base as catalyst.At the same time,when different Lewis bases are used,we can get polymers of different topologies-ring and linear;When carbene is used as the catalyst,the carbene will preferentially attack the double bond conjugated with the carbonyl group,then carry out chain growth by Michael addition,forming zwitterion during the chain growth process,and finally terminate the chain by anion attack on the LB⁺initiating group forming cyclic polymer.when potassium tert-butoxide or organic superbase phosphazene ligand P4-tert-butyl（t-Bu-P4）is used as a catalyst,the organic base first deprotonates the monomeric carbonylα-H,then chain-growth in the same manner as Michael addition,The difference is that when organic bases are used,there are no departable groups at the beginning of the chain,thus forming a linear polymer.The ring-opening polymerization of two lactone derivatives was also studied.We modified the two lactones with cyclopentadiene to obtain a monomer with spiro ring structure.On the one hand,we hope to increase the ring tension of monomers to make it easier to initiate ring opening polymerization,and on the other hand it is desirable that the introduction of a rigid ring can alter the thermodynamic properties of the polyester.The results show that the structure ofγ-butyrolactone was more non-polymerizable after the introduction of the spiro ring.On the contrary,the polymerization of theδ-valerolactone derivative under the catalysis of the metal complex was well controlled,and the degradation rate of the obtained polymers could reach more than 95%after adding Sn（Oct）₂ at 150℃in vacuum for 12 hours.