Syntheses And Properties Of Benzoxazine Copolymer Containing Double Bond And Its Cured Polymer

The 5G era requires copper clad laminate(CCL)to obtain the functions of high frequency,high speed,large capacity storage,miniaturization.The signal transmission rate is inversely proportional to the square root of dielectric constant,and the signal loss is directly proportional to the square root of dielectric constant and dielectric loss.In order to meet the requirements of 5G communication,we must use polymer materials with low dielectric constant(<2.5)and low dielectric loss(<0.005)to reduce the reduction of transmission rate and signal loss.Polyolefine,also known as hydrocarbon resin,is a polymer synthesized by unsaturated hydrocarbon containing vinyl or diene.It has excellent low dielectric properties(Dk<2.0,Df<0.003),because it only contains carbon and hydrogen elements and has no molecular polarity.Maleimide resin has excellent heat resistance and dimensional stability.The double bond in maleimide can only be copolymerized,which can not be homopolymerized.The copolymer of maleimide monomer and olefin monomer has excellent low dielectric properties(Dk<2.0,Df<0.004).However,the heat resistance of the copolymer can not meet the require-ments of post-processing of copper clad laminate.At the same time,the adhesion between copolymer and metal is also poor,which leads to poor processability.Therefore,it is necessary to modify the resin system.Benzoxazine is a six membered heterocyclic intermediate with nitrogen and oxygen atoms,which is synthesized from primary amines,phenols,and formaldehyde.Ring opening polymerization occurs under heating or catalysis,and the resulting polymer with cross-linked network structure is called benzoxazine resin or poly-benzoxazine.Benzoxazine resin has the advantages of good heat resistance,good dimensional stability,low moisture absorption,and flexible molecular design.At the same time,it has good dielectric properties,and especially the dielectric loss can remain stable in a wide frequency range.Based on the above advantages,benzoxazine resin has been widely used in the field of copper clad laminate.Based on the flexibility of benzoxazine molecular design,benzoxazine monomers with different double bonds were synthesized.Meanwhile,styrene-maleimidobenzoxazine,styrene-allylbenzoxazine,and styrene-styrylbenzoxazine,and styrene-maleimide-maleimidobenzoxazine,styrene-maleimide-styrylbenzoxazine ter-polymer for high frequency and high speed copper clad laminates were synthesized by copolymerization of the synthesized benzoxazine monomers with styrene monomer and maleimide monomer.Subsequently,the copolymer was heated to open the ring to synthesize the cured polymer.The specific research contents of this thesis are as follows:1.Allylbenzoxazine was synthesized from allylamine,paraformaldehyde,and phenol.Maleimidobenzoxazine and styrylbenzoxazine were synthesized by the reaction of 4-maleimide phenol and 4-vinylphenol with aniline and paraformaldehyde respectively.Three kinds of benzoxazines with different double bond and non-polar styrene were used as reaction monomers,and styrene-benzoxazine copolymer with double bond was synthesized by AIBN initiator.Finally,the copolymer was heated to open the ring and the styrene-benzoxazine cured polymer was synthesized.The molecular weight and structure of the three copolymers were studied by GPC,1H-NMR,and FTIR.The heat resistance,thermal stability,and dielectric properties of the three copolymers were further studied by DMA,TGA,and dielectric constant tester.The results show that the three cured polymers have excellent low dielectric properties.The cured styrene-styrylbenzoxazine copolymer has the best low dielectric properties.At 1GHz,the dielectric constant is 2.45 and the dielectric loss is 0.0053.The glass transition temperature(Tg)of cured styrene-styrylbenzoxazine copolymer is 200℃,and the temperature of 5%weight loss(Td5)is 296℃.2.Styrene-maleimide-maleimidobenzoxazine terpolymer was synthesized by copolymerization of styrene monomer,N-phenylmaleimide monomer and maleimide benzoxazine monomer initiated by AIBN.The copolymers were heated to form styrene-maleimide-maleimidobenzoxazine cured copolymer.The molecular weight and structure of the copolymer were characterized by GPC,1H-NMR,and FTIR.The heat resistance,thermal stability,and dielectric properties of the cured copolymer were further studied by DMA,TGA,and dielectric constant tester.The results show that the cured polymer has excellent dielectric properties.At 1GHz,the dielectric constant is 2.15 and the dielectric loss is 0.0057.The cured polymer has excellent thermal properties,Its Tg is 215℃ and Td5 is 390℃.3.Styrene-maleimide-styrylbenzoxazine terpolymer was synthesized by copoly-merization of styrene monomer,N-phenylmaleimide monomer,and styrene monomer initiated by AIBN.The copolymers were heated to form styrene-maleimide-styrylbenzoxazine cured copolymer.The molecular weight and structure of the copolymer were characterized by GPC,1H-NMR,and FTIR.The heat resistance,thermal stability,and dielectric properties of the cured copolymer were further studied by DMA,TGA,and dielectric constant tester.The results show that the cured polymer has good dielectric properties.At 100MHz,the dielectric constant is 2.01 and the dielectric loss is as low as 0.0053.The copolymer has excellent thermal property.Its Tg is 190℃ and Td5 is 375℃.