RAFT Polymerization Technology For The Rosin Based Functional Polymers As Well As Its Structure And Properties

Rosin,one of important forestry chemical products featured with biodegradable,renewable and abundant,has been widely used to preparation of polymer materials for its high value utilization.In particular,converting rosin and its derivatives into monomers for the synthesis of rosin-based functional polymer materials by controlled polymerization,has become an important research hotspot in this field.In this paper,dehydroabietic acid,one of rosin acids,was firstly used to synthesize a rosin-based monomer bearing an acrylate functional group.This rosin based monomers with the inherent rigid structure and hydrophobic properties was then used to fabricate a serials of biomass-based ethyl cellulose graft copolymers and amphiphilic block copolymers via reversible addition-fragmentation chain transfer polymerization?RAFT?.Additionally,dispersion polymerization of rosin monomer and styrene were also studied.The detail of our search is described as follows.In first section,we reported a strategy to prepare a series of grafted copolymers from rosin,fatty acids and ethyl cellulose.The process involved the preparation of EC-based macro-RAFT agent through a simple esterification reaction,followed by a“grafting from”RAFT of DAGMA?derived from rosin?and LMA?derived from fatty acid?to achieve a class of EC-g-P?DAGMA-co-LMA?graft copolymers with a tunable T_g tuned by the DAGMA/LMA molar ratio.The structure of macromolecular RAFT reagent and graft copolymer was studied by ¹H NMR and GPC.The thermodynamic properties,ultraviolet absorption properties and mechanical properties of the graft copolymer were characterized by TGA,DSC,UV-vis,DMA and the universal test machine.The results showed that the introduction of rosin monomer endowed the graft copolymers with better thermal stability.The glass transition temperature increased with the increment of the molar ratio of rosin-based monomer.All these polymers showed an excellent UV absorption performance.Then,hexamethylene diisocyanate?HDI?was used to crosslink these graft copolymers.The mechanical and dynamic thermo-mechanical properties of tests showed that elastic recovery values of copolymers were enhanced to 90%,as compared to the un-crosslinked samples.This study provides a facile way to fabricate biobased elastomeric materials with improved mechanical properties.In the second section,a range of rosin-based amphiphilic block copolymers were prepared throughthe RAFT polymerization.Hydrophilic poly?ethylene glycol?methyl ether methacrylate?PEGMA?homopolymer were prepared at first step through the RAFT polymerization.Then PEGMA homopolymer was used as macromolecular RAFT reagent to further carry out RAFT polymerization of DAGMA to synthesize rosin-based amphiphilic block copolymer PPEGMA-b-DAGMA.The obtained block copolymers were characterized by ¹H NMR,FT-IR and GPC.The results indicated that the polymerization reaction was controllable and the polymerization kinetic curve was linear.TGA and UV-vis showed that the block copolymer have better thermal stability and ultraviolet absorption properties due to the introduction of the rosin segment.Surface tension meter,DLS and TEM studies showed that the self-aggregation behavior of block copolymers in aqueous solution.Block copolymers capable of aggregating into a spherical structure of micelles.With the growth of hydrophobic segments in the block copolymer,the obtained micelle size increased from 97 nm to 142 nm.In addition,the drug loading experiments of the block copolymer on the model drug DOX showed that the micelles have a drug-loading capacity.In the third section,dispersion polymerization of styrene in an aqueous alcohol solution using amphiphilic block copolymer PPEGMA-b-DAGMA as a stabilizer,and AIBN was used as the initiator was performed to prepare monodisperse stable polystyrene microspheres.The effects of dispersant content,initiator concentration,monomer dosage,dispersion medium and reaction temperature on the polymerization were studied.The structure of the polymer microspheres,the morphology and size of the microspheres were characterized by FT-IR,SEM,DLS,GPC.The results showed that the microspheres prepared by the ethanol-water system have a more uniform distribution with a size of 90 nm.The particle size of the PS microspheres decreased with the amount of the dispersant.While increasing the initial styrene concentration from 0.5 g to1.5 g,the bimodal distribution of PS microspheres obtained.It was also found that the larger the amount of initiator,the smaller the molecular weight of the polymer.Considering the conversion rate and the particle size distribution of PS microspheres,the suitable reaction temperature of this system was 70^oC.In the fourth section,a new type of monodisperse microspheres consisted of poly?2-methacryloyloxyisopropanol ester of dehydroabietic acid??PDAGMA?was prepared via dispersion polymerization in the presence of isopropyl alcohol/H₂O,using2-methacryloyloxyisopropanol ester of dehydroabietic acid?DAGMA?as a monomer,polyvinylpyrrolidone?PVP?as stabilizer,2,2'-azobis?2-methylpropionitrile??AIBN?as an initiator.And these microspheres were crosslinked with cross-linking agent for the adsorption of rutin solution.FT-IR,¹H NMR,GPC and SEM were applied to characterize the structure,morphology and size of the microspheres,respectively.The influences of PVP content,monomer concentration and reaction temperature on the particle size and distribution of microspheres were investigated.The results showed that the DAGMA monomer could polymerized in the alcohol/water medium.GPC analysis showed that the relative molecular weight of the polymer was about 55000 g/mol.By the optimize the polymerization technology,monodispersed microspheres with particle size 1.37?m and PDI 1.014 were obtained.Specially,the cross-linked rosin polymer microspheres exhibited an improved thermal stability and the adsorption capacity of rutin was 12.3 mg/g.In addition,PPEGMA was then used as the dispersion stabilizer and a chain transfer agent for the dispersion polymerization of DAGMA,a stable dispersed emulsion was obtained with particle size changing from 2.05?m to 0.92?m.Moreover,the particle size decreased with the hydrophobic chain length longer of PPEGMA.