Study On Controlled Polymerization For Preparation Of Bio-based Myrcene Functional Elastomers And Its Properties

Synthetic rubber has excellent chemical and physical properties,low manufacturing cost,and superior processing performance.It has been widely used in modern human life.The production and utilization of synthetic rubber has become an important indicator to measure the national economic development of the country.However,traditional synthetic rubber raw materials are all from petrochemical products,which contradicts the concept of vigorously advocating the development of green and sustainable materials in the new era.Scientists are struggling to find biological monomers to replace irreversible and environmentally harmful petroleum-based raw materials,and terpene biological compound—myrcene has become a research hotspot.Such monomers are only composed of carbon and hydrogen,and the lack of polar groups leads to poor surface properties and bonding properties of polyolefins.Therefore,in this paper,a series of new bio-based myrcene-derived polarities were synthesized on the basis of myrcene monomer,and its structure was characterized.Reversible addition fragmentation chain transfer（RAFT）method and Neodymium catalyst-initiated coordination polymerization method were used for polymerization,and the new functional elastomer prepared was studied in detail.1.Designed and synthesized five kinds of myrcene-derived monomers based on the bio-based myrcene,and the radical bulk homopolymerization of myrcene-derived monomers was successfully achieved by RAFT method.Under this polymerization system,the polymer has a relatively high yield（>65%）and a high 1,4-structure（about 90%）.In the study of its performance testing,it has relatively stable thermal properties(T_{g My-EPO}=-14 ^oC<Tg My-OH-Py=13 ^oC<Tg My-OH-Fu=18 ^oC<Tg My-OH=21 ^oC<Tg My-（OH）2=40 ^oC);With the addition of polar groups,the hydrophilicity is also more obvious,both of which are lower than the contact angle of polymyrcene（WCA=121^o）.When the polymer contains dihydroxy groups,the polymer’s WCA=21.5^o.It can be clearly seen from the AFM morphology of the polymer that the rubber phase with polar parts protrudes fr om the surface and is evenly distributed.In the kinetic study,the molar mass of the polymer has a linear relationship with the conversion rate,and the correlation coefficient R²=0.9,highlighting the controllability of the polymerization process.2.Radical bulk copolymerization of My/My-EPO,St/My-EPO,and St/My-OH was achieved by RAFT method.The microstructure of the polymer is mainly 1,4-structure（>92.5%）,and the proportion of the polar portion in the copolymer corresponds to the feeding ratio of the polar monomer,such as f（My-EPO:My=20:80）,then F（My-EPO:My=27.9:72.1）.the polymer has stable thermal properties.As the polar content increases（10mol%-50mol%）,the glass transition temperature（T_g）of My/My-EPO copolymer increases（-47 ^oC–-35 ^oC）,and the contact angle decreases significantly（118.3^o to 85.0^o）;The T_g of St/My-EPO copolymer decreased from 45.9 ^oC to 6.3 ^oC,and the hydrophilic effect changed significantly（54.7^o to 30.4^o）;The T_g of St/My-OH copolymer increased from 28 ^oC to 65 ^oC,the hydrophilicity increased（98.9^o to 89.5^o）.It can be seen from the AFM morphology diagram that the polar part of the polymer is uniformly dispersed.3.Adopt Nd（vers）₃/AlⁱBu₃/Al Et₂Cl catalyst system to obtain myrcene homopolymer with high cis-1,4（>90%）structure.At the same time,different proportions of myrcene are added to isoprene and butadiene during the copolymerization,the polymer main chain is still dominated by cis-1,4（>91%）,and the glass transition temperature is-79 ^oC–-61 ^oC,which has good thermal stability.And for the first time,a neodymium catalyst was used for the coordination polymerization of My/My-OH,and a polymer with a high cis-1,4（>90%）structure was successfully obtained.With the introduction of polar groups,the glass transition temperature from-66 ^oC of PMy to-47 ^oC.As the content of polar groups increases,the hydrophilicity becomes stronger（WCA=99^o–89^o）.This paper modified the myrcene monomer,designed and synthesized a new bio-based myrcene-derived sustainable monomer,and successfully introduced the polar group into the non-polar myrcene.A variety of methods were used to systematically investigate the homopolymerization and copolymerization behavior of polar monomers and their polymer properties,providing novel functionalized polymers for the synthesis of sustainable materials.