Synthesis And Applications Of Bio-based Citronellic Polyesters/Polyolefins

Biomass resources are considered as renewable due to their abundant reserves,diverse types,cleanliness,and safety.Their exploitation aligns with the principles of sustainable development and the concept of circular economy in modern society.The scientific significance and research value of using renewable biomass as raw materials to produce polymers to replace petrochemical-based polymers cannot be overstated.In recent times,there has been a rapid development of polymers based on terpenes and terpenoids.However,the research on bio-based citronella polymers has significantly fallen behind other natural terpene polymers.This is mainly due to the high spatial site resistance and low polymerization activity of multi-substituted double bonds found within citronella compounds.In this subject paper,we thoroughly investigated not only the thermal and mechanical properties,as well as the degradation behaviors of the related materials,but also demonstrated the functional applications of the polymers.1.We designed and synthesized 9-membered cyclic lactone monomers,which we used to prepare linear and three-armed star-shaped aliphatic polyesters through organocatalytic ring-opening polymerization.We then converted the three-armed starshaped polymers into free-standing elastomeric films through UV irradiation-induced cross-linking.To better understand the properties of these materials,we systematically investigated their thermal properties,mechanical properties,and chemical recovery characteristics.The tri-substituted double bond was successfully converted into a conjugated double bond using a cross-translocation reaction between the natural product citronellol(a downstream product of citronella oil)and methyl acrylate.The amorphous aliphatic polyesters were obtained by ring-opening polymerization of 9-membered cyclic lactones catalyzed by organic bases.The presence of methyl side chains resulted in the polymer chains showing irregular stacking.Under UV light irradiation,the three-armed starshaped polymers with acrylate end groups were cross-linked to form self-supporting films.In addition,both the resulting polyester and elastomer films were able to achieve methanolysis catalyzed by organic bases to give ω-hydroxy acid methyl esters.This compound can be used both for the synthesis of monomers and directly for the polycondensation to obtain linear polyesters.2.ω-bromo acids were synthesized from citronellol,and a series of bio-based polyesters were prepared by stepwise polymerization using inexpensive inorganic bases as catalysts.The effects of side chain and carbon chain length on the polymer properties(e.g.thermal properties,mechanical properties,and crystallization ability)were investigated in detail.The 9-membered cyclic lactone from the previous chapter was used as the starting material and ring-opened in the presence of hydrobromic acid to obtain an AB-type ω-bromo acid monomer,which successfully avoided the adverse effect of dehalogenation by-products on the polycondensation reaction.The monomer was randomly copolymerized with castor oil derivative 11-bromoundecanoic acid in the ratios of 20/80,40/60,60/40,and 80/20 to prepare all plant-based aliphatic polyesters.Polymer nanoparticles were obtained by the nanoprecipitation method,and then hydrophobic nanoparticles were obtained by surface modification,and the suspension can be used as a spray to achieve superhydrophobic modification of the material surface.3.Citronellyl vinyl ketone monomers were designed and synthesized,and then biobased polyolefins were obtained by photo-induced electron transfer–reversible addition–fragmentation chain transfer polymerization(PET-RAFT)polymerization,and alcoholsoluble bio-based poly(vinyl ketone)s were obtained by deprotection,and a variety of functional coatings were constructed from them.Conversion of citronellol to vinyl ketone monomers using peroxy acid epoxidation and enol interconversion isomerization.A series of bio-based polyolefins were obtained using PET-RAFT polymerization by adjusting the chain transfer agent/monomer feed ratio.The silicone-protecting groups of the side chains were removed by deprotection reactions to obtain alcohol-soluble poly(vinyl ketone)s.By mixing them with powder materials(e.g.pigments,phosphors,magnetic conductive nanoparticles,etc.),various functional coatings can be obtained.