Degradable polymers Degradable polymers with low-temperature formability Functionalization of degradable polymers Degradation mechanism of polymers

Membrane separations CO2 separation membranes CO2 capture by electrodialysis

Degradable polymers with low-temperature formability

  Multi-component polymers show pressure-induced phase transition at a constant temperature, Baroplastics. Especially, effect of pressure applied on two-component systems, such as block copolymers, has been intensively studied. We have figured out that degradable polymers from polycaprolactones and polylactides exhibit pressure-induced phase miscibility and can be processable at ambient temperature under pressure. The degradable block copolymers have a separated structure (solid state) upon microphase separation at ambient conditions, which is going to a miscible phase (melt state) under pressure. The degradable polymers with low-temperature formability are environmentally benign and drastically reduce required energy in processing, leading to decrease CO₂ emission. We also found those polymers prepared from CO₂ and other renewable resources, which would hold potential to be “game-changing polymeric materials”.

 

 

I. Taniguchi, et al. Macromolecules, 2012

 

 

 

Functionalization of degradable polymers

  Polyesters are obtained by ring-opening polymerization of lactones (cyclic esters) and lactides (cyclic dimers of lactic acid), and the properties can be determined by those chemical structures. For chemical modifications, it has been unenviable to introduce functional groups onto the polymer backbone. We have succeeded functionalization of polyesters by grafting functional groups through a chemoselective reaction between aminooxy group and ketone. This chemoselective approach can broaden opportunity of polyesters for use.

 

 

1. Highly reactive partners tolerate the presence of diverse functional groups.
2. Reaction proceeds rapidly under mild reaction condition.
3. Two partners react covalently to form stable oxyme linkage.

I. Taniguchi, et al. Macromolecules, 2005

 

 

 

Degradation mechanism of polymers

  One of the biggest challenges of degradable polymers is how to control the degradability, which can be characterized by chemical structures, crystallinity, molecular weight, and composition if copolymers. Elucidation of the detail degradation mechanism would provide useful information to design and synthesis of polymeric materials with timed degradation. Biodegradation of hardly degradable polymers, such as PET, is also an important research topic.

 

 

S. Yoshida, et al. Science, 2016

 

 

 

CO₂ separation membranes

  Mitigation of CO₂ emission is an urgent issue to suppress the Global warming and Climate change, and various CO₂ capture technologies have been examined at a CO₂ mass emission source, such as thermal power stations. Membrane separation is an energy saving process and highly expected as a next generation CO₂ capture technology. In this laboratory, membrane materials have been prepared for CO₂ capture at the various emission sources. Especially, we have developed promising polymeric membranes for CO₂ separation over H₂. Those polymeric membranes would be applicable not only for pre-combustion CO₂ capture at an integrated gasification combined cycle plant but also for carbon-free H₂ production at current steam reforming process of light hydrocarbons.

 

 

I. Taniguchi, et al. J. Mater. Chem. A, 2013

 

 

 

CO₂ capture by electrodialysis

  Liquid amine scrubbing, current CO₂ capture technology, has been studied for post-combustion CO₂ capture at demonstration scale. However, large energy consumption in CO₂ recovery limits the implementation. We proposed an alternative CO₂ capture method by electrodialysis. CO₂ separated in an alkaline solution is condensed by electrodialysis, and the CO₂ is then regenerated under vacuum. The required energy for CO₂ capture is much lower than that of the current method. A key for further energy reduction is to develop ion-exchange membranes with lower membrane resistances.

 

 

I. Taniguchi, et al. J. Chem. Lett., 2014