One of the key challenges for the commercialization of carbon nanotube fibers (CNTFs) is their large-scale economic production. Among CNTF spinning methods, surfactant-based wet spinning is one of the promising techniques for mass producing CNTFs. Here, we investigated how the coagulation bath composition affects the spinnability and the properties of CNTFs in surfactant-based wet spinning. We used acetone, DMAc, ethanol, and IPA as coagulants and analyzed the relationship between coagulation bath composition and the properties of CNTFs in terms of kinetic and thermodynamic coagulation parameters. From a kinetic perspective, we found that a low mass transfer rate difference (MTRD) is favorable for wet spinning. Based on this finding, we mixed the coagulant bath with solvent in a proper ratio to reduce the MTRD, which generally improved the wet spinning. We also showed that the coagulation strength, a thermodynamic parameter, should be considered. We believe that our research can contribute to establishment of surfactant-based wet spinning of CNTFs.

본 연구에서는 sigle-walled carbon nanotube (SWCNTs)에 재조합된 고정산화효소를 부착한 고정효소제제를 이용하여 방향족 탄화수소의 생화학적 분해를 고찰하였다. Arthrobacter chlorophenolicus A6로부터 복제 및 대량발현 하여 얻어진 hydroquinol 1,2-dioxygenase는 방향족 탄화수소의 ring-fission를 활성화하는 것으로 나타났다. 이와 같이 재조합되어 획득된 dioxygenase를 SWCNTs에 고정시켰다. SWCNTs의 표면은 비이온계 계면활성제로 표면처리/활성화하였고, 이를 통해 SWCNTs의 수용액상 dispersivity가 크게 증가함을 확인하였다. 고정화 수율은 62%였고, 효소고정이후 효소활성도의 60-70%가 유지되었다. 효소의 동역학적 분석 결과, 기질이용률(Vmax)과 촉매효율(Vmax/KM)의 측면에서 고정된 효소는 동역학적 특성이 거의 유사하게 나타나 고정된 효소의 활성도 손실이 최소한으로 유지될 수 있음을 알 수 있었다. 고정화 된 효소는 pH, 온도, 이온강도의 변화에도 자유 효소보다 더 높은 안정도를 유지하는 것으로 나타났다. 또한, 효소 재사용 시에도 활성도가 높게 유지되는 것으로 나타났다. 이러한 결과들은 계면활성제를 이용한 SWCNTs의 표면처리 및 효소고정 기법이라는 새로운 효소 고정화 기술 개발에 적용할 수 있을 것으로 기대된다. 또한, 본 연구에서의 CNT를 이용한 효소고정제재를 이용한 고효율의 친환경적, 경제적인 난분해성 유기오염물질의 생화학적 분해 기법 개발의 기초를 제공할 것으로 기대된다.

This study was aimed to investigate the difference in strength of Carbon Nanotube (CNT) reinforced cement mortars with different types of surfactants and doses. In the experimental program, CTAB, SDBS and TX10 which were common surfactants adopted to improve CNTs dispersion in fabricating CNT composites in many industrial fields were included and superplasticizer which was revealed to be effective to disperse CNTs especially in CNT reinforced cementitious composites were added as well. Superplasticizer presented less strength reduction in cement mortar and more strength gain by adding CNTs among four types of surfactants. Higher dosage of superplasticizer caused lower strength of cement mortar. Adding CNTs of 0.4 wt.% or less to cement didn’t show strength enhancement by adding CNTs but 0.8 wt.% of CNTs resulted in strengthening effect after all. Finally, a combination of 0.1 wt.% of CNTs, superplasticizer and sonication treatment could lead to strength improvement by adding CNTs in cement mortar.