Preparation Of Hyperbranched Poly(Ether Ether Ketone)s And Their Study As Rheology Control Agents For Linear Poly(Ether Ether Ketone)s

Hyperbranched polymers have their unique physical and chemical properties due to their highly branched structure. Their globular shape, followed by the low hydrodynamic volume and melt viscosity make them can be used as a rheology modification for linear polymer with high melt viscosityA fast and highly efficient approach for the synthesis of hyperbranched poly(ether ether ketone)s (HPEEKs) via the polycondensation of A2 and BB'2 monomers is described. Commercially available hydroquinone (HQ, A2 monomer) and easily synthesized 3,4',5-trifluorobenzophenone (TF-1, BB'2 monomer) and 2,4',6-trifluorobenzophenone (TF-2, BB'2 monomer) were thermally polycondensed to prepared fluoro- or phenolic-terminated HPEEKs with K2CO3 and Na2CO3 as catalysts. During the reaction, the fluorine at the 4'-position of TF reacts rapidly with the phenolic group of HQ, forming predominantly dimers and some other species. The dimer can be considered as a new AB'2 monomer. Further reactions among molecules AB'2 and AB'2 with some other species result in the formation of HPEEKs. The structures of the resultant polymers was revealed by IR,1H-NMR and 19F-NMR spectra.19F-NMR spectra The degree of branching of fluoro-terminated hyperbranched poly (ether ether ketone) of TF-1 series was determined to be in the range 28-52%, whereas the degree of branching of phenolic -terminated hyperbranched poly(ether ether ketone) of TF-1 series was determined to be 100%. The degree of branching of fluoro-terminated hyperbranched poly (ether ether ketone) of TF-2 series was determined to be in the range 50-57%, whereas the degree of branching of phenolic -terminated hyperbranched poly (ether ether ketone) of TF-2 series was determined to be 100%. These hyperbranched polymers exhibit excellent solubility in general organic solvents, and possess moderate molecular weights with the broad distributions. Moreover, the structure and performance of the HPEEKs can be conveniently regulated by adjusting the type and feed ratio of the two monomers.Linear poly (ether ether ketone) (LPEEK) with high melt viscosity was blended with hyperbranched poly (ether ether ketone) (HPEEK) to enhance its melt process ability without sacrificing comprehensive performance. The advantage of using HPEEK was its unique spherical shape, low melt viscosity and its easy access. Rheological measurement showed that blending LPEEK with as little as 1% HPEEK resulted in about 17% reduction of melt viscosity for HPEEK of TF-2 series. LPEEK/HPEEK blends only existed one glass transition temperature (Tg), indicating complete miscibility which resulted from similar molecular structure. The HPEEK content, as heterogeneous nucleating agent and rheology modifier, accelerated the crystallization rate of LPEEK. Remarkably, the mechanical properties of LPEEK increased within 3% content of HPEEK. The good miscibility was proposed to be responsible for the improved mechanical properties. Moreover, the addition of HPEEK slightly increased the thermal stability of LPEEK.The above aforementioned hyperbranched poly (ether ether ketone) (HPEEK) was amorphous, which make the application of linear poly (ether ether ketone) (LPEEK) be limited if LPEEK and HPEEK were blended. So we try to prepare crystalline hyperbranched poly (ether ether ketone) using methods of homopolymerization and copolymerization. However, the crystalline hyperbranched poly (ether ether ketone) was not obtained using the methord of homopolymerization, because the homopolymerization was limited due to the activity. We adopted random copolymerization and block copolymerization to prepare the crystalline hyperbranched poly (ether ether ketone). In the case of random copolymerization, we prepared five ratios of hyperbranched poly (ether ether ketone), in which the ratio of TF-2: B2 was from 1:1 to 1:5. Hyperbranched poly (ether ether ketone)s were prepared successfully, as proven by NMR. Moreover, HPEEK was crystalline polymer when TF-2:B2≥1:3 TF-2: B2=1:3. In the case of block copolymerization, we also prepared five ratios of hyperbranched poly (ether ether ketone), in which the ratio of TF-2-OH:B2 was from 1:4.03 to 1:8.03. Hyperbranched poly (ether ether ketone)s were prepared successfully, as proven by NMR. Moreover, HPEEK was crystalline polymer when TF-2-OH:B2≥1:6.03. Linear poly (ether ether ketone) (LPEEK) and the resultant hyperbranched poly (ether ether ketone) (HPEEK) was blended. Four kinds of hyperbranched poly (ether ether ketone) (random copolymer, TF-2:B2=1:3 and 1:4; block copolymer, TF-2-OH:B2=1:6.03 and 1:7.03) were choosen as rheology modification. The results shows that the melting viscosity wasn't reduced when the addition amount of random copolymer was 5%, while the melting viscosity reduced 20% when the addition amount of block copolymer was 5%,and their mechanical properties and thermal stability did not present obvious change.