Preparation Of Novel Methacrylate-based Thermoplastic Elastomers

Acrylic thermoplastic elastomers have rubber characteristics and thermoplastic properties,which are available at high temperature and can be plasticized.Acrylic ester has flexible segments,and polar ester groups of side chain could provide properties of heat-resistance,oilresistance and other characteristics.In this paper,a new-style of full acrylate thermoplastic elastomer was prepared using lauryl methacrylate(LMA)and tetrahydrofurfuryl methacrylate(THFMA)as the main monomers,in which LMA acted as soft segment and THFMA acted as rigid segment.The main contents and conclusions are as follows:(1)The solution copolymerization reaction was carried out using LMA and THFMA as monomers.In order to determine the copolymerization type,the ratio of the two monomers was quantified according to 1H-NMR analysis,and reactivity ratio of the two monomers was studied according to Mayo-Lewis equation.Random copolymer was obtained by solution copolymerization reaction of LMA and THFMA using DMF as solution at 70 ℃.The reaction rate and monomer concentration showed first order reaction.The prepared copolymer was characterized by GPC,DSC,NMR and FT-IR methods.Reactivity ratio of THFMA and LMA was 0.43 and 2.30,which was obtained by F-R method and K-T method.And the results showed that the copolymerization behavior of LMA and THFMA accorded with the ideal copolymer model.The F1 of THFMA in the copolymer and the f1 of THFMA in the monomer composition were increased as the increase of conversion rate.(2)The activity polymerization of LMA was investigated by using potassium cyanide dithiobenzoate(CPDB)as RAFT reagent.The effects of temperature,monomer and RAFT reagent dosage on polymerization reaction were analyzed.The segmented copolymer P(LMAb-THFMA)was prepared using THFMA as monomer and the prepared poly(lauryl methacrylate)as RAFT reagent by polymerization reaction.The prepared copolymer was characterized by gel permeation chromatography.RAFT polymerization of LMA was carried out in THF solution using CPDB as chain transfer reagent and AIBN as initiator.The polymerization process showed good activity/controllable characteristics,The GPC results showed that the polymer molecular weight could be controled,molecular weight distribution was narrow,and molecular weight increased with the increase of the conversion rate.RAFT polymerization was affected by temperature.The polymerization at the lower temperature had a longer induction period,and it showed better first order kinetics with the increase of the polymerization temperature.The rate of polymerization was affected by the concentration of chain transfer reagent.Polymerization rate decreased and was controllable with the increasing of the concentration.And the polymerization became uncontrollable and the molecular weight distribution was wide with the decrease of chain transfer reagent.(3)Active controllable reaction of SI-ATRP was carried out by grafting reaction of P(LMAco-THFMA)on the surface of nanocellulose(CNCs)using EBi Br as the sacrificial initiator.Cellulose-based thermoplastic elastomers(CNC-TPEs)was prepared by in situ recombination of linear polymer P(LMA-co-THFMA)and grafted copolymer CNCs-g-P(LMA-co-THFMA).Besides,a series of CNC-TPEs with different composition,molecular weight and glass transition temperature were prepared by adjusting the ratio of LMA and THFMA.And the mechanical properties of CNC-TPEs were tested.The CNCs-Br initiator was prepared by esterification of 2-bromoisobutyryl bromide with hydroxyl groups on the surface of nanosized cellulose(CNCs),and LMA and THFMA were grafted to the the surface of CNCs in the presence of sacrificial initiator(EBi Br).The FT-IR,NMR and GPC results showed that linear polymer P(LMA-co-THFMA)was grafted to CNCs successfully.DSC results showed that the glass transition temperature of CNC-TPEs was improved due to the presence of CNCs.The mechanical properties of CNC-TPEs were improved obviously by introducing CNCs,and the tensile strength and elongation at break of composites were increased with the increase of THFMA in the composites.However,when the ratio of THFMA and LMA was less than 1,the tensile strength of the composites was very low,which was less than 2 MPa,but the elongation at break reached 500 %.