Bio-based polyamides (PAs) are polyamides that are fully or partially synthesized from renewable resources. They can offer high levels of heat resistance, stiffness and high mechanical stability for a durable solution which are same as the chemically synthesized polyamides. In addition to their sustainability, these bio-based starting materials can provide special structural features to the resulting polymers and their properties, e.g., side groups, functionalities, or stereo information. Bio-based polyamides have been recently attracting attention due to the increasing awareness of green chemistry.
Polyamide
Synthesis Routes
Two routes, polycondensation (step-growth polymerization with water as side product) and ring-opening polymerization (ROP), can be used for the synthesis of bio-based polyamides.
Bio-based polyamides are basically formed from polycondensation of bio-based dicarboxylic acids and diamines and of bio-based α, ω-amino acids, or they can be derived from carbohydrates, terpenes, and rosin acids via polycondensation.
Example (1)
Ricinoleic acid (from castor oil) is the starting compound for two different routes, the undecenoic acid route and the sebacic acid route, two acids that are both important monomers for bio-based polyamides (Figure 1) [1].
Fig. 1 Monomers and polyamides from castor oil
(Left: synthesis of Nylon-11 via polycondensation of 11-aminoundecanoic acid. Right: Cleavage of ricinoleic acid to sebacic acid and its transformation with different diamines to the corresponding polyamides.)
Example (2)
Figure 2 shows exemplarily the synthesis of poly(alkylene galactaramide)s (PAGalA) from dimethylgalactarate (DMG) and of poly(alkylene D-glucaramide)s (PAGluA) from methyl D-glucaracte 1,4-lactone (MGL).
Fig. 2 Polyamides based on galactaric acid and a glucarate lactone
- Ring-opening Polymerization
Ring opening polymerization (ROP) of lactams is a highly efficient and versatile method to synthesize polyamides.
Example (3)
Lysine, obtained from glucose, can be cyclized and deaminated to produce ε-caprolactam (CL). Besides, bio-based ε-caprolactam can be synthesized form 5-hydroxymethylfurfural (obtained from, e.g., D-fructose), which is first converted into ε-caprolactone in two steps, and then ε-caprolactone is transformed into ε-caprolactam by using ammonia. Polyamides can be synthesized through the ring opening polymerization of ε-caprolactam.
Fig. 3 Synthesis of ε-caprolactam (CL) and Nylon-6 starting from C6 sugars A) via lysine, B) via 5-Hydroxymethylfurfural
Applications
The functional amide group which facilitates an internal hydrogen bond between the chains of bio-based polyamides, leads to properties such as hardness, good impact strength and excellent abrasion resistance. As with these excellent performance, bio-based polyamides are used in many (demanding) applications such as automotive fuel lines, pneumatic air brake tubing, electrical cable jacketing, flexible oil and gas pipes, and powder coatings. Some novel applications include toothbrushes, carpets, tires, sporting goods (sports shoes and outdoor apparel), and electronic casings.
Our Bio-based Polyamides
Unlike the even-carbon structure of traditional petroleum-based products, Alfa Chemistry's bio-based polyamides have an odd-numbered-carbon molecular structure. Our high quality bio-based polyamides can yield excellent characteristics such as flame retardancy, moisture absorption, easy dyeing, low warpage, and high flowability etc. And they have renewable carbon content as high as 45%-100%. This effectively reduces the use of products made from fossil raw materials such as petroleum, and thus reduces carbon emissions.
Alfa Chemistry is a professional supplier of bio-based polyamide. For high quality products, professional technical service, use suggestion and latest industry news, please feel free to contact us.
Reference
- Malte Winnacker, Bernhard Rieger. Bio-based Polyamides: Recent Advances in Basic and Applied Research. Macromol. Rapid Commun. 2016.
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