Abstract
Living organisms, such as, plants, animals and microorganisms produce various biopolymers while consuming minimal amounts of energy. This study investigates the formation mechanisms of structural biopolymers and applies mechanisms, such as controlling the molecular orientation or allowing the polymer to self-organize, in order to synthetically reproduce biopolymers whose properties mimic those found naturally. Establishing energy efficient polymer system technologies for biopolymers, such as proteins, will allow the reduction of energy consumption in many polymer processing applications. Silk is one example of a biopolymer produced with minimum energy requirements. Silk is a fine, lustrous, filament produced by the silkworm, Bombyx mori, after it has consumed large amounts of naturally grown mulberry leaves. It has appealing fiber characteristics including its pearl-like gloss, velvety touch and is comfortable to wear in all seasons. The silkworm accurately controls the molecular orientation by combining numerous sophisticated spinning technologies such as liquid crystal, high speed spinning, dry spinning, super drawing, ion control, complex spinning, porous and crimp spinning. We also show that silkworms and a silk-producing spider incorporate atmospheric CO2 into their silk fibers. We found that C13-labelled CO2 under controlled atmospheric conditions is incorporated into silk fibers in the carbonyl groups of alanine, aspartic acid, serine and glycine and the Cγ of aspartic acid. These results demonstrate that silkworm has incorporated atmospheric CO2 into silk fiber via the TCA cycle. Finally, it is important that we reconstruct the energy-efficient polymer system technology of these biopolymers with aims to reduce energy consumption in many other polymer processing applications.
