聚芳醚腈-聚硅氧烷嵌段共聚物的合成

采用4-烯丙基-2-甲氧基苯酚(Eugenol)为端基的聚二甲基硅氧烷与氟代苯端基含杂萘联苯结构聚芳醚腈,以碳酸钾为催化剂,二甲基亚砜与邻二氯苯为溶剂的条件下进行芳香亲核取代反应(SNAr),合成了一种高分子量的聚芳醚腈-聚硅氧烷嵌段共聚物,并采用FTIR和1H-NMR对该产物的结构进行了表征.DSC测试结果表明该类嵌段共聚物具有两个玻璃化转变温度(Tg),分别为-98～-90℃和255～287℃,而且共聚物具有优良的耐热性,10%的热失重温度(Td)在450℃以上.采用原子力显微镜和透射电镜观测发现该共聚物存在明显的相分离特征.

SYNTHESIS AND CHARACTERIZATION OF POLY(PHTHALAZINONE ETHER NITRILE)-POLYDIMETHYLSILOXANE BLOCK COPOLYMERS

High molecular weight block copolymers with different backbone compositions were synthesized from eugenol end-capped polydimethylsiloxane(PDMS)and fluorophenyl-terminated poly(phthalizinone ether nitrile)(PPEN)oligomers.These oligomers of PPEN were prepared via S_NAr step-growth polymerization from 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one(DHPZ)and 2,6-difluoro-benzonitrile(DFBN)using DMSO as solvent at 180℃.The oligomers with well-defined fluoro-terminated and various quantitative molecular weights were obtained by using an excess of DFBN.The number-average molecular weight(M_n)values of PPEN oligomers ranged from 3100 to 10500.The eugenol terminated PDMS oligomers were prepared by reacting silane terminated PDMS with eugenol in toluene via the well-known Pt-catalysed hydrosilation reaction.The phenol-group of eugenol was protected by trimethylchlorosilane in the hydrosilation to avoid side reactions and loss of functional group,and the aryl-trimethylsilyl ethers can be cleaved by refluxing in aqueous methanol.The M_n values of PDMS oligomers were 4550 and 7220,respectively.The block polycondensation was carried out in the presence of dimethyl sulfoxide/o-dichlorobenzene and K_2CO_3 as solvents and catalyst at 180℃ by the S_NAr reaction.The M_n values of block copolymers ranged from 19400 to 25100.The results of GPC indicated that reaction of two oligomers occurred and then the higher molecular weight copolymers were obtained.It further suggested that the new synthesis method is an effective and convenient approach to prepare similar PDMS based block copolymers.The structure of copolymers obtained was characterized by FTIR and 1H-NMR.Differential scanning calorimetry analysis indicated that the block copolymers showed two glass-transition temperatures(T_g) at-98～-90℃ and 255～287℃,respectively.The distinct two T_g's in the block copolymers suggested that microphase separation occurred in the block copolymer.The copolymer also showed a high thermal stability with 10% weight-loss temperatures in excess of 450℃ in nitrogen according to thermogravimetric analysis.The migration of PDMS segments to the copolymer surface was observed directly by atomic force microscope(AFM) and transmission electron microscope(TEM).PDMS expanded to the continuous phase on the surface,suggesting that PDMS segments were rich on the surface.The PPEN phase as the particle cavities was dispersed in copolymer surfaces with diameters of 0.1～0.3 nm.