2

2'-[1

1'-biphenyl］- 4

4'-diylbis(oxy)］bis［6-fluoro-benzonitrile］ monomer was synthesized from 4

4'-biphenol (BP) and 2

6-difluorobenzonitrile (DFBN) through pseudo high dilution

then reacted with the bisphenol-like monomer

4-(4-hydroxyphenyl)-phthlazin-1(2H)-one (DHPZ) to obtain alternate-like copolymer (a-PPEBN) by nucleophilic substitution.Random copolymer (r-PPBEN) was synthesized from BP

DFBN and DHPZ through a one-step procedure.Gel permeation chromatography (GPC) test showed that the two methods could both obtain a high molecular-weight polymer with average number molecular weight of 2.4 104 for r-PPBEN and of 3.4 104 for a-PPEBN.Intrinsic viscosity of a-PPBEN was 0.96 dL/g in chloroform at 25℃ and that of r-PPBEN was 0.94 dL/g.The structure of the monomers and polymers were confirmed by Fourier transform infrared spectroscopy (FTIR)

nuclear magnetic resonance (NMR)

mass spectrum (MS) and element analysis.The tests showed that the two kinds of copolymer displayed different crystallization properties and thernostability in spite of having the same chemical composition.Thermogravimetric analysis (TGA)

differential scanning calorimetry (DSC)

dynamic mechanical thermal analysis (DMA) tests demonstrated that a-PPBEN had better thermal stability

higher glass transition temperature (Tg) and storage modulus than r-PPBEN.Tg of a-PPBEN was almost 10 K higher than that of r-PPBEN

suggesting that a-PPBEN possessed more regular rigid structure than r-PPBEN.Spherocrystal patterns of r-PPBEN under polarizing microscope indicated that some micro blocks of PBEN segments were derived from the reaction of BP and DFBN.Wide-angle X-ray diffraction (WAXD) tests also proved the indication.The copolymers all showed good solubility by virtue of introducing twisted

non-coplanar phthalazinone moieties into the backbone of the polymers.At room temperature

the two kinds of copolymers were soluble in a variety of aprotic polar solvents

such as N-methyl-2-pyrrolidinone (NMP)

chloroform N

N-dimethylacetamide (DMAc) etc.