Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE credits
Polyamides are an important and versatile family of plastics commonly used both as construction plastics and fibers. The global consumption of polyamides has grown quickly, from 800 000 tons per year in 1990 to 2 500 000 tons per year in 2011. Polyamides are highly crystalline and consequently have high melting points. This makes the synthesis of polyamides a highly energy consuming process.The objective of this thesis is to find a synthesis route for polyamides using an enzymatic catalyst. To be able to use enzymes the melting point of the synthesized polyamide needs to be lowered, otherwise the oligomers will solidify before growing to long chains. Since the high melting point is a consequence of the crystallinity the project has applied two routes to lower the crystallinity. The first route, route 1, by using long, branched monomers, and the second route, route 2, by using monomers with an unsaturation in the repeating unit. There are, to my knowledge, only a limited number of studies on polymerization of polyamides using enzymes.Experiments in this report were done at a small laboratory scale. The enzyme used was Candida antarctica lipase B (CALB). The monomers used in route 1, were produced by addition of thiols with different end groups to the internal double bond of methyl oleate. The reactions worked yielding functional monomers used for polyamide synthesis. When cysteamine, coupled to methyl oleate was polymerized the reaction was fast and the limiting factor was viscosity. The degree of polymerization, DP, for the polymerization was 8. Monomers from methyl-3-mercapto propionate and methyl oleate were co-polymerized with diamines of varying lengths. When 1,6-diaminohexane was used solubility problems arose. But the use of the longer diamine, 1,12-diaminedodecane, generated a homogenous system with a conversion of 80% of the monomer from methyl-3-mercapto propionate and methyl oleate and oligomers with a DP of 3. Methanol and chloroform were used as solvents to solvate the shorter diamine, but resulted in a low DP.Route 2 used trans β-Hydromuconic acid and its corresponding dietser. The reactions did not reach the high conversions of monomers needed for a high DP. The main problem was, again, the solubility of 1,6-diaminohexane. As a proof of concept a polyester synthesis was performed in route 2, since there has been more research within this area. The polyester contained an unsaturation in the backbone. The synthesis reached a high conversion and a DP of 11.This thesis is a study of which the important factors are in order to take synthesis of polyamides using enzymatic catalysts further. Complementary work has to be done, but the project has shown that it is possible to synthesis oligoamides with lower crystallinity using CALB as catalyst.