高折光指数光学树脂的合成——相转移法合成不饱和硫醇酯单体的条件控制

采用正常的低温相转移催化（ＰＴＣ）和反滴碱溶液ＰＴＣ法分别合成了含硫双烯ＭＥＳＤＭＡ和单烯ＭＥＰＳＭＡ．１Ｈ ＮＭＲ分析证明ＭＥＳ中的杂质主要是由原料ＴＤＧ引入的．对含单个巯基的ＭＥＰＳ的正常ＰＴＣ酯化接枝双键，因存在巯基和不饱和双键的加成反应而导致失败．作者最终得到了折光指数在１６２５以上的ＭＥＳＤＭＡ／ＭＥＰＳＭＡ共聚物．

SYNTHESES OF HIGH REFRACTIVE INDEX OPTICAL RESINS --SYNTHESES OF UNSATURATED MONOMERS FROM THIOLS BY PHASE TRANSFER CATALYSIS REACTION

Plastic materials for optical products are strongly required to exhibit high refractive index and low dispersion (with less chromatic aberration),and the most convenient and effective way is to introduce sulfur element into polymer structures.Therefor,2,2' mercaptoethyl sulfide (MES) dimethacrylate (MESDMA) and p phenylthioethyl thiolmethacrylate (MEPSMA) were synthesized by normal phase transfer catalysis (PTC) and special PTC reaction (dropping caustic solution),respectively.The double bond containing monomers (MESDMA and MEPSMA) and their precursor thiols (MES and p phenylthioethanethiol (MEPS)) were characterized and corroborated by 1H NMR and FTIR spectra.According to the analysis of 1H NMR,the foreign substance in MES was caused by thiodiglycol (TDG),and it can not be eliminated by distillation of MES or TDG.Due to the results of monomer synthesis and polymerization,the little amount of foreign substance in MES has no disadvantageous affect,through quality control,the MES can be used directly.It was proved by 1H NMR and FTIR spectra that the addition reaction between the mercapto of MEPS and the double bond in normal PTC condition leads to the failure of double bond containing monomer (MEPSMA) synthesis.In the condition of special PTC reaction,the thiolate (RS- anion) of MEPS is just appeared following with the dropping of caustic solution,its amount in the organic layer maintains lower and it is more easily to react with MC,which is large amount and freely to move,not with MEPSMA,which is big volume and difficult to move,so MEPSMA can be successfully synthesized by this way.The special PTC reaction,i.e.dropping caustic solution not MC,is the best way to prepare double bond containing monomers from thiols and MC in characterizations of light color,high purity and high yield,especially for those double bond containing monomers with higher molecular weight and difficult to refine.MESDMA/MEPSMA transparent copolymer resins with refractive index higher than 1.625 were obtained by casting the monomers and initiator into glass molds,polymerized in an oven according to a definite curing program.Some basic properties of the resins,e.g.refractive index,Abbe number,density and impact strength etc.are measured finally. 