POLYMERS Vol.72　No.1 January 2023

POLYMERS　Vol.72　No.1

COVER STORY
Polymers for Green Transformation

COVER STORY: Highlight Reviews

Chemical Recycling of Plastics by Pyrolysis That Contributes to Collaboration between Arterial and Venous Industries

Toshiaki YOSHIOKA, Shogo KUMAGAI

<Abstract> Efforts related to chemical recycling of plastics are becoming more active from the perspective of the circular economy (CE), and collaboration between arterial and venous industries rooted in the carbon cycle is essential. In particular, it will be important to expand the range of conditions in which arterial and venous technologies can be traded for the development of technologies for converting waste plastics and biomass into basic chemical raw materials.
Keywords: Waste Plastics / Chemical Recycling / Collaboration between Arterial and Venous Industries

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CO₂ Separation Membranes

Eiji KAMIO

<Abstract> An increase in atmospheric CO₂ concentration is causing various global environmental problems. CO₂ separation is an important technology for preventing CO₂ emissions and reducing CO₂ concentration in the atmosphere. Membrane separation technology has the potential to realize an energy-saving and compact CO₂ separation process. To this end, development of a high-performance CO₂ separation membrane composed of a highly and selectively CO₂ permeable material is indispensable. In this article, the theoretical consideration of the CO₂ permeation mechanism is highlighted and the design guidelines and characteristics of the polymer materials used for novel high-performance CO₂ separation membranes such as PIMs, TR polymers, and ion gels are introduced.
Keywords: CO₂ Separation / Membrane / Solusion-Diffusion Mechanism / PIMs / TR Polymers / Ion Gels

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Catalytic Synthesis of Aliphatic Polycarbonates from Carbon Dioxide and Diols

Keiichi TOMISHIGE, Masazumi TAMURA

<Abstract> Aliphatic polycarbonates have been synthesized by a variety of stoichometric reactions: diols＋phosgene, diols＋CO₂＋alkaline carbonates＋halides, and so on. Another approach is the catalytic synthesis of polycarbonates. It has been known that cerium oxide is an efficient catalyst for the selective synthesis of dimethyl carbonate (DMC) from CO₂ and methanol. However, it is difficult to obtain high yields of DMC due to the severe equilibrium limitation. The combination of the DMC synthesis with the hydration of 2-cyanopyridine, where both reactions are catalyzed by cerium oxide, gives very high yields of DMC. This methodology was also applied to the synthesis of polycarbonates from CO₂ and diols using 2-cyanopyridine or 2-furonitrile. The removal of H₂O from the reaction system was carried out by the gas stripping method using atmospheric CO₂. This demonsrates the possiblity of the synthesis of polycarbonates from diols and low pressure CO₂.
Keywords: Cerium Oxide / Heterogeneous Catalyst / Carbon Dioxide / Aliphatic Polycarbonate

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Energy-Saving CO₂ Chemisorption Process Using Phase Change Sorbent

Yoshimi SEIDA

<Abstract> The chemical absorption/adsorption method of CO₂ using amines is the practical separation and recovery method that can respond to various load conditions of CO₂. Since this method consumes much energy in the CO₂ desorption/regeneration process, various energy-saving methods have been studied and developed. This paper focuses on research that achieves significant energy savings by utilizing the phase change of absorption liquids and adsorbents and will introduce their characteristics and research trends.
Keywords: Carbon Dioxide / Chemisorption / Phase Separation / Adsorbent / Sorbent

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Polymer Science and I: A Personal Account

Toward a Soft-Matter Architect

Shunto ARAI

<Abstract> This essay presents my research history as an aspiring “soft-matter architect.”

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Front-Line Polymer Science

Interfacial Engineering Based on Precise Design of Polymer Structure

Yukari ODA

<Abstract> This article shortly introduces recent research on the control of interfacial structure and functions based on precise design of primary structure of polymers by considering the contributions towards surface free energy. To construct hydrophilic interfaces, utilization of interfacial segregation and interfacial reconstruction in contact with water of amphiphilic copolymers is useful. By utilization of surface segregation behaviors of branched polymers in the linear polymer matrix, selective interfacial modifications can also be achieved. Based on the better understanding of interfacial behaviors of polymers, precise design and development of highly functionalized polymers can be expected.
Keywords: Interface / Primary Structure / Surface Free Energy / Segregation / Entropy / Block Copolymer / Branched Polymer

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