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<p>Polycarbonate (PC) is a high-performance engineering thermoplastic known for its optical clarity and mechanical strength. However, enhancement of glass transition (T<sub>g</sub>) temperature of BPA based PC (~ 145&#xa0;°C) could play a vital role in the material applications at high-temperature and this could be achieved by incorporating rigid and flexible moieties into the polymer backbone. The incorporation of an appropriate comonomer ratio is a key parameter for tuning polymer properties while maintaining essential polycarbonate characteristics such as transparency, ductility, and Tg. Three effective rigid (aromatic based diimide) and flexible (-C(CF<sub>3</sub>)<sub>2</sub>-, -C(CH<sub>3</sub>)<sub>2</sub>-) bishydroxy diimide comonomers were successfully synthesized. In addition, bisphenol A (BPA) was recovered from waste polycarbonate through a chemical depolymerization process and reused as a monomer for polymer synthesis. A series of Co-Poly (Diimide-carbonates) (Co-PDICs) were synthesized by incorporation of different ratio (2&amp;3%) of rigid aromatic diimide units into the BPA-based polycarbonate backbone via Triphosgene method. The structure of synthesized comonomers and polymers were characterized by FT-IR, <sup>1</sup>H-NMR, <sup>13</sup>C-NMR and GPC analysis. The thermal properties of the polymers were performed by Differential Scanning Calorimetry (DSC) and Thermo Gravimetric analysis (TGA). DSC results showed that T<sub>g</sub> increased gradually from 147&#xa0;°C to 175&#xa0;°C as the comonomer ratio in the polymer structure was raised up to 10&#xa0;mol%. However, incorporating more than 10&#xa0;mol% of the comonomer led to a noticeable loss of transparency in the polycarbonate. TGA analysis shows that the degradation temperature of PC was enhanced from ~ 450&#xa0;°C to 465&#xa0;°C due to the incorporation of diimide moieties. GPC analysis confirmed the successful formation of high-molecular-weight copolymers. Co-PDICs-3 exhibited a higher number-average molecular weight (Mn = 7.11 × 10<sup>4</sup> g mol<sup>−</sup><sup>1</sup>) and a lower polydispersity index (Mw/Mn = 3.01) than Co-PDICs-2, indicating improved molecular weight uniformity. This research suggests that incorporating both rigid and flexible moieties can enhance the thermal properties of the polymer.</p>

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Tuning thermal properties of co-polyimide carbonates via rigid and flexible segment incorporation

  • 期刊论文

  • 发表日期：

    2026年7月20日

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  • R. Lokeshwari,
  • A. Murugesan,
  • Loganathan M,
  • M. Surendiran

摘要

Polycarbonate (PC) is a high-performance engineering thermoplastic known for its optical clarity and mechanical strength. However, enhancement of glass transition (Tg) temperature of BPA based PC (~ 145 °C) could play a vital role in the material applications at high-temperature and this could be achieved by incorporating rigid and flexible moieties into the polymer backbone. The incorporation of an appropriate comonomer ratio is a key parameter for tuning polymer properties while maintaining essential polycarbonate characteristics such as transparency, ductility, and Tg. Three effective rigid (aromatic based diimide) and flexible (-C(CF3)2-, -C(CH3)2-) bishydroxy diimide comonomers were successfully synthesized. In addition, bisphenol A (BPA) was recovered from waste polycarbonate through a chemical depolymerization process and reused as a monomer for polymer synthesis. A series of Co-Poly (Diimide-carbonates) (Co-PDICs) were synthesized by incorporation of different ratio (2&3%) of rigid aromatic diimide units into the BPA-based polycarbonate backbone via Triphosgene method. The structure of synthesized comonomers and polymers were characterized by FT-IR, 1H-NMR, 13C-NMR and GPC analysis. The thermal properties of the polymers were performed by Differential Scanning Calorimetry (DSC) and Thermo Gravimetric analysis (TGA). DSC results showed that Tg increased gradually from 147 °C to 175 °C as the comonomer ratio in the polymer structure was raised up to 10 mol%. However, incorporating more than 10 mol% of the comonomer led to a noticeable loss of transparency in the polycarbonate. TGA analysis shows that the degradation temperature of PC was enhanced from ~ 450 °C to 465 °C due to the incorporation of diimide moieties. GPC analysis confirmed the successful formation of high-molecular-weight copolymers. Co-PDICs-3 exhibited a higher number-average molecular weight (Mn = 7.11 × 104 g mol−1) and a lower polydispersity index (Mw/Mn = 3.01) than Co-PDICs-2, indicating improved molecular weight uniformity. This research suggests that incorporating both rigid and flexible moieties can enhance the thermal properties of the polymer.