Synthesis And Properties Of Copolyarylates Containing Phenol Red Units

As a high-performance special engineering plastic,polyarylates are widely used in the electronics industry,mechanical aerospace,medical and 5G new materials.The relatively regular and ordered rigid molecular chain structure of polyarylates gives it excellent performance,while its solubility and processability are limited to different degrees.Physical modification of polyarylates has received attention,however,this does not fundamentally solve the problem of complex application environment requirements faced by polyarylates materials.In this paper,BPA/PR type copolyarylates containing phenol red unit were synthesised from molecular structure design by introducing bulk pendant groups into the molecular chain through reactivity calculations.On this basis,BPB/PR type copolyarylates were successfully prepared using bisphenol B monomers containing flexible asymmetric ethyl side groups instead of conventional bisphenol A monomers,and the relationship between the structure and properties of the polyarylates was systematically investigated.Aiming at the excellent thermal stability of the reaction products and expanding application scenarios,the ternary phase diagram of the polyarylates dissolved in the solvent/non-solvent system was systematically investigated.The effect of polyarylate coating of PE separators was initially studied,and the effects of polymer and non-solvent concentrations on the coating structure and thermal shrinkage of separators were examined.The main findings are as follows:1.Novel BPA/PR type copolyarylates（APR）containing PR units were synthesized by interfacial polymerization using bisphenol A（BPA）,phenol red（PR）and dichloride monomer.The number-and weight-average molecular weight（M_n and M_w）were 1.0×10⁴-4.6×10⁴ and 3.9×10⁴-20.4×10⁴,respectively.DFT（density functional theory）simulations showed that the required reaction activation energy for the reaction of BPA with terephthaloyl chloride and isophthaloyl chloride（TPC and IPC）was 6.3-6.6 Kcal/mol,while the activation energy required for PR was 59.2-59.4 Kcal/mol.The polyarylates were amorphous and could be cast in solution to produce homogeneous,transparent and tough pale yellow films.The processing temperature of the copolyarylates was ameliorated by adding a small amount of PR units,and the glass transition temperature（T_g）of the polymer decreased from 202.8°C to 166.7°C,while the copolyesters still maintained excellent thermal stability with maximum thermal decomposition temperature(T_max)in the range of 532.4-545.2°C.The polyester film has excellent mechanical properties,with a tensile strength of 57.6 MPa and Young’s modulus of 2.0 GPa at a PR content of 15 mol%.2.A series of novel copolyarylates（BPR）containing flexible ethyl side groups and PR pendant groups were synthesised using BPB instead of BPA.The inherent viscosity(η_inh)of the obtained amorphous copolyarylates ranged from 0.2-0.7 d L/g and the Mn from 1.1×10⁴-1.8×10⁴ g/mol.DFT calculations indicated that the reactivity of BPB was similar to BPA,with the reaction activation energy required for BPB to participate in the reaction was 8.1-8.4 kcal/mol,and the reactivity of PR was relatively lower.Under the influence of the flexible asymmetric ethyl side group of BPB and the PR pendant group,the solubility and processing temperature of the copolyarylates were further ameliorated,T_g decreased with increasing PR unit content and its thermal stability could still be maintained at a high level,with T_max in the range of 525.7-527.4°C.The residual carbon rate increased with the increase of PR content to 32.7%with increasing PR content.Tensile strength ranged from 46.8-58.6 MPa.All the aromatic copolyesters exhibit good mechanical properties and easy processability.3.The cloud point of the polyarylate/solvent/non-solvent ternary system was determined by non-solvent-induced phase separation method,the ternary phase diagram was drawn,and the polyarylate coated PE separators with grid coating structure was prepared.The results showed that both the concentration of the copolyarylate and the content of the non-solvent methanol could affect the coating structure,with higher solute and non-solvent content tending to form irregular microporous structures,the pore sizes rising from 1-2μm to 6-8μm,and lower methanol content tending to form uniform and regular lattice-like pore structures.The use of polyarylate to coat PE separators could significantly improved the heat resistance of the diaphragm,and the higher the concentration of polymer,the more stable the size of the coated separator.The effect of non-solvent methanol on shrinkage was not significant.The addition of APR or BPR at only 1 wt%could maintain dimensional stability at 130°C,while reducing the thermal shrinkage of the coated separators from 71%to 42%at 150°C.As the concentration of copolyarylates increased to 3wt%,the shrinkage rates of APR and BPR at 150°C decreased to 9.8%and 16.4%,respectively.Figure 41 Table 12 References 108...