Flexible all‐aromatic polyesterimide films with high glass transition temperatures

Abstract

A series all-aromatic poly(esterimide)s with different molar ratios of N-(3 0 -hydroxyphenyl)-trimellitimide (IM) and 4hydroxybenzoic acid (HBA) (IM/HBA 5 0.3/0.7 and 0.7/0.3) was prepared with the aim to design flexible high T g films. Melt-pressed films, either from high molecular weight polymer or cured phenylethynyl precursor oligomers, exhibit T g s in the range of 200 8C to 242 8C and are brittle. After a thermal stretching procedure, the films became remarkably flexible and very easy to handle. In addition, the thermally stretched 3-IM/7-HBA and 7-IM/3-HBA films show tensile strengths of 108 MPa and 169 MPa, respectively. Thermal treatment increased the T g of 3-IM/7-HBA from 205 8C to 248 8C, whereas the T g of 7-IM/3-HBA increased from 230 8C to 260 8C.Most ketone-, ether-, and amide-based monomers are symmetric two-ring moieties. Imide-based monomers, on the other hand, are nonlinear or kinked three-ring systems. [21][22][23][24][25][26][27] The aromatic content is increased but the asymmetry suppresses T m Additional Supporting Information may be found in the online version of this article.

High-performance all-aromatic liquid crystalline esteramide-based thermosets

“…After reaching the minimum value, the viscosity of HNA/TA/AAP(20)–Ref starts increasing and leveling off after a 20-min hold at 370°C, suggesting that transesterification and polymerization are taking place during the heating ramp and isothermal hold (effectively, postcondensing the polymer). 25 In the case of HNA/TA/AAP(20)–5 K, chain extension and cross-linking are taking place from 320°C resulting in an increase in molecular weight and hence a rapid increase in |η*|. After a 25-min hold at 370°C, the chain extension and cross-linking chemistry are mostly complete and the viscosity levels off.…”

The Thermal Properties and Degradability of Chiral Polyester-Imides Based on Several l/d-Amino Acids

“…Chiral PEIs (PEI3a–PEI3d′) were synthesized by direct polycondensation of diacid monomers (2a–2d′) with 4,4′-dihydroxydiphenyl ether under the reported method (see step 2 in Scheme 1 ) [ 25 , 26 , 27 ]. Yields and physical properties of PEIs are shown in Table 2 .…”

Facilely Synthesizing Ethynyl Terminated All-Aromatic Liquid Crystalline Poly(esterimide)s with Good Processability and Thermal Resistance under Medium-Low Temperature via Direct Esterification

“…N -(3′-Hydroxyphenyl)­trimellitimide (IM) was synthesized according to the method reported previously. , Typically, glacial acetic acid (130 mL) and TMA (0.05 mol, 10.51 g) were mixed at 120 °C until all solids were dissolved, and then 3-AP (0.05 mol, 5.46 g) was added. A thick suspension was formed almost immediately, and this reaction mixture was refluxed for 4 h at 120 °C.…”

“…Recently, a series of reactive all-aromatic liquid crystalline poly(esterimide) (LCPEI) oligomers were synthesized via melt polycondensation at high temperature (∼310 °C), and as the molecular weights of thermosetting LCPEI block copolymers reduce, T m and |η*| tend to decrease and the processability will be gradually improved; however, the cured thermosets exhibit double T g (120 and 220 °C). 22,23 In addition, the esterification or transesterification reaction of melt polycondensation usually takes place at high temperature (250−320 °C), so the reactive end groups must keep latent. Up to date, only PEPA and norbornene are two available compounds.…”

“…Therefore, researchers tried to combine different modification methods in order to fulfill the requirements of good processability and high thermal resistance. Recently, a series of reactive all-aromatic liquid crystalline poly­(esterimide) (LCPEI) oligomers were synthesized via melt polycondensation at high temperature (∼310 °C), and as the molecular weights of thermosetting LCPEI block copolymers reduce, T m and |η*| tend to decrease and the processability will be gradually improved; however, the cured thermosets exhibit double T g (120 and 220 °C). , In addition, the esterification or transesterification reaction of melt polycondensation usually takes place at high temperature (250–320 °C), so the reactive end groups must keep latent. Up to date, only PEPA and norbornene are two available compounds. , Liquid crystalline polymers terminated with PEPA or norbornene have a curing temperature up to 370 °C, which severely restricts their practical applications.…”