A novel crosslinkable fluorinated poly(ether ether ketone) with acetylenylbenzene end groups was prepared by solution condensation. The chemical structure of such polymer was confirmed by FTIR and 1H NMR. The crosslinking behavior and thermal stability were investigated by DSC and TGA respectively. The DSC thermogram for the first heating run shows a glass transition of 6F-PEEK at about 395 K and a exothermic peak correspongding to the self-crosslinking reaction of fluorinated poly(ether ether ketong) at about 700 K. For the second heating run, the exothermic peak disappered and the glass transition shifted to a higher temperature. The crosslinked polymer shown excelent thermal stability and solvent-resistence. The temperature for 5% weight loss was 774 K and the self-crosslinked polymer was no more disolved by polar solvents, which disolved in before crosslinking, such as DMF, DMAc and NMP. This kind of polymer may be a potential material used as electro-optical devices.
Block copolymers containing poly(aryl ether ketone) unit and different lengths of thermotropic liquid crystalline polyesters(TLCP) segments were synthesized by high temperature solution polymerization. The chemical structure, thermal properties and liquid crystalline behavior of the block copolymers were investigated by FTIR, DSC and PLM respectively. A single glass transition revealed that the two blocks had good a compatibility. The length of TLCP segment had a significant influence on the copolymers′ liquid crystalline behavior. When the molecular weight of TLCP reduced to 2965, liquid crystallinity of copolymer disappeared. The block copolymers showed a typical nematic threaded texture which differed from polyester′s.
The soluble poly(vinyl alcohol)-g-poly(ethylene glycol) monomethyl ether(PVA-g-MPEG) graft copolymer was prepared by two-step synthesis. The structure of the PVA-g-MPEG was characterized by 1H NMR. The phase change and crystallization behavior were analyzed by DSC and POM. The phase change behavior presented solid-to-solid state; the phase transition process was reversible. Compared with pure MPEG, the phase change temperature and enthalpy of graft copolymer declined because of the addition of PVA. Due to the intermolecular interaction and chemical bond, the crystalline shape of the graft copolymer was changed.
A novel bifluoro-monomer containing naphthalene moieties was synthesized and characterized by using FTIR, MS and NMR. Different poly(aryl ether ketone)s based on 1,4-bis(4,4′-fluorobenzoyl) naphthalene were prepared via aromatic nucleophilic substitution reaction. The polymers with a high molecular weight can be readily obtained due to the highly activity of the used monomer. 3F-PEEK-nK and 6F-PEEK-nK polymers were determined to exhibit good thermal stabilities with high T-g of 450 K and 457 K, respectively. Moreover, these polymers show a satisfactory solubility and can be cast into flexible and transparent films.
A new monomer, 1,4-bis(4-fluorobenzoyl) naphthalene(compound 2) was synthesized via a two-step reaction. 1,4-Naphthalenedicarboxylic acid chloride(compound 1) was prepared by using the acyl chlorization reaction of 1,4-naphthalenedicarboxylic acid with thionyl chloride. The Friedel-Crafts acylation of compound 1 with fluorobenzene afforded compound 2 in a 80% yield. The polycondensation of compound 2 with various bisphenols in tetramethylene sulfone(TMS) in the presence of excess potassium carbonate as a condensation reagent was carried out at 210 ℃ to quantitatively afford the corresponding poly(aryl ether ketone)s(compounds 3_8) containing 1,4-naphthalene moieties. Thermal analyses showed that the polymers have T g values ranging from 496 to 500 K and are thermally stable in air with initial mass loss above 500 ℃. These novel polymers exhibited an excellent solubility in organic solvents including NMP, DMAc, and chloroform, etc. In addition, the glass transition temperatures of these polymers increased and the polymers became insoluble in chloroform after treated at 260 ℃, indicating the occurrence of a thermal crosslinking reaction.
C1s and O1s of the 3,5-bitrifluoromethylated poly（aryl ether） terminated with phenylethynyl moieties（2CF3-PAE-PEP） before/after crosslinking were tested by the X-ray photoeletron spectroscopy（XPS）. The measurements show that some of the C\O bonds in the molecule structure will be broken if the films are crosslinked in the air, which is able to form some new CO bonds with the oxygen in the air. However, the ratios of the groups in the films cured in nitrogen remain the same as that of the uncured samples. It is the the forth harmonic of the stretching vibration of CO bond(4νφC=O) that causes the absorption loss at the wavelength 1 382 nm.
