Industrial Consultancy & Sponsored Research (IC&SR) , IIT Madras
A Method of Synthesis of PBAT Using Group 4 and Group 13 Initiators
Technology Category/Market
Category- Chemistry and Chemical Analysis
Industry:
Chemicals manufacturing; Plastics and Polymers Industry
Applications:
Packaging Films- Compostable bags, cling films, and pouches; Agricultural Films- Mulch films and crop‑protection sheets; Disposable Tableware: Cutlery and plates; Courier Bags- Biodegradable mailing envelopes; Textiles & Apparel- Fibers and non‑woven fabrics; Pharmaceutical Materials- Biodegradable drug‑delivery matrices.
Market report:
The global PBAT market was valued at USD 1,928 million in 2024 and is projected to reach USD 4,792 million by 2035, growing at a CAGR of 8.6%
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Problem Statement
- Biodegradable poly(butylene adipate-co-terephthalate) PBAT synthesis offers a sustainable alternative to petroleum‑based plastics, reducing environmental pollution and supporting circular economy goals in packaging and agriculture.
- Existing aliphatic polyesters (e.g., PLA, PCL) suffer high costs and poor mechanics; while aromatic PET lacks biodegradability, limiting widespread eco‑friendly applications.
- Conventional PBAT syntheses yield moderate molecular weights (<300 kDa) with side‑reactions, long reaction times, and require complex co‑catalysts, affecting processability and scalability.
- There is a need for a novel initiator that uses earth‑abundant metals to achieve ultra‑high molecular weight PBAT (>300 kDa) with narrow PDI at simpler conditions, with improved properties.
Technology
- Equimolar dimethyl terephthalate and 1,4‑butanediol (0.15 mol each) are esterified at 150–200 °C for 1.5–4 h under N₂ (45 mL/min), removing methanol to form bis(hydroxyalkyl) intermediates
- Upon methanol cessation, adipic acid and 1,4‑butanediol (0.15 mol each) are added; reactor heated to 210–230 °C for 6 h to distill water, driving polycondensation
- Pressure lowered to ~0.01 mbar; temperature ramped to 280–300 °C over 20–30 h, yielding viscous PBAT with molecular weights up to ~1.15 × 10⁶ g/mol.
- Employs 0.05 wt% Group 4 (tetraisopropyl titanate) or Group 13 (THF‑coordinated Al‑propoxide/bimetallic Al) initiators, offering tunable reaction times (2–5 h for step a; 20–28 h for step b)
- Crude PBAT is suspended in CHCl₃, filtered, then vacuum‑dried 8–10 h; final polymer exhibits PDI > 1.0 and Mn in the range 2.4 × 10⁴–1.15 × 10⁶ Da.
Key Features/Value Proposition
- Achieves PBAT molecular weights up to ~1.15 × 10⁶ g/mol, surpassing literature reports (<3 × 10⁵ Da) for superior mechanical strength.
- Utilizes inexpensive, non‑toxic Group 4 (Ti) and Group 13 (Al) initiators, avoiding precious or hazardous metals common in other systems.
- Simplifies formulation by omitting additional co‑catalysts, reducing material costs and post‑processing purification steps.
- Delivers polymers with PDI ≈1.0–1.18, enabling uniform melt behavior and consistent performance in film‑blowing or extrusion processes.
- Combines esterification and polycondensation in a single reactor under moderate temperatures (150–280 °C) and reduced pressure, minimizing reaction time and energy.
Questions about this Technology?
Contact for Licensing
Research Lab
Prof. Debashish Chakraborty
Department of Chemistry
Intellectual Property
- IITM IDF Ref 2887
- IN 202441065905 Patent Application
Technology Readiness Level
TRL 4
Technology Validated in Lab