高分子 Vol.70 No.2
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特集 精密と曖昧のええ加減
展望 COVER STORY: Highlight Reviews
Molecular Weight Distribution and Block Polymer Self-Assembly Nathaniel A. LYND, Mahesh K. MAHANTHAPPA, and Atsushi NORO
<要旨> Complementary theories and experiments have revealed how molecular weight distribution breadth impacts microdomain sizes, composition-dependent phase boundaries, and order state stabilities of block polymer soft materials. Recent developments in precision syntheses of discrete block polymers and those with controlled molecular weight distribution shapes promise deeper insights into the self-assembly of disperse inhomogeneous block polymers and greater control over their properties and applications.
Keywords: Morphology / Mesoscopic Phase Separation / Segment Dispersity / Order-Disorder Transition (ODT) / Skewness
Manipulation of Backbone Orientation in Semiconducting Polymers
尾坂 格
<要旨> さまざまな分野で分子配向の重要性が説かれている。ポリマー半導体でも、ポリマー主鎖の配向は電荷輸送性を決定する重要因子の一つである。すなわち、ポリマー半導体の配向を自在に制御することができれば、高性能な光・電子デバイスの創出が期待できる。本稿では、筆者らのポリマー半導体の配向制御による有機薄膜太陽電池の高効率化に関する研究について紹介する。
Keywords: Semiconducting Polymers / π-Conjugated Polymers / Orientation / Intermolecular Interaction / Organic Field-Effect Transistors / Organic Photovoltaics / Charge Transport
Development of Superabsorbent Polymers with Moderately Controlled Structures Using Iodine Transfer Polymerization
宮島 徹
<要旨> 制御ラジカル重合は特殊構造ポリマーを中心に限定的な領域で実用化されてきた。本稿では、ヨウ素移動重合による“ええ加減”な制御を紙おむつ用の高吸水性樹脂に適用した、従来 とは一線を画する実用化事例を紹介する。それとともに40年前の日本企業発の技術の融合に至った経緯を振り返りながら、精密重合を実用化に繋げるための筆者の考えを述べる。
Keywords: Superabsorbent Polymer / Iodine Transfer Polymerization / Gel / Controlled Polymerization
トピックス COVER STORY: Topics and Products
Functions of Vitrimers Provided by Cross-Linked Structures with “Associative” Bond-Exchange Mechanism
林 幹大
Mikihiro HAYASHI
<要旨> Vitrimers are a new class of cross-linked materials, which have been recently invented to solve the problem of conventional cross-linked materials such as, poor recyclability and healability. In this article, fundamental characteristics and physical properties of vitrimers are demonstrated. In vitrimer networks, the bond-exchange occurs without distinct separated steps of bond dissociation and re-association, and such exchange mechanism is nowadays referred to as “associative” dynamic bond exchange. During the bond-exchange, the network topology is constantly altered with keeping the network integrity and constant cross-link density, which is the biggest uniqueness for vitrimer networks. Owing to the above nature, vitrimers show some useful functions that cannot be attained in thermoplastic and thermosetting polymers. Among various functions, re-processability without sudden flow at high temperatures is an outstanding function of vitrimers. This is enabled by the very gentle temperature dependence of viscosity change, which is described by an Arrhenius-type relationship, unlike the WLF-type relationship for thermoplastics.
Keywords: Associative Dynamic Covalent Bond / Vitrimer / Cross-Linked Material / Network Topology Alternation
Two-Dimensional Films of Organic Semiconductors Realized Through Layer-Number Controlling Technique
荒井 俊人
Shunto ARAI
<要旨> We have developed a unique solution-based technology to form ultrathin two-dimensional organic-semiconductor layers with single-molecular bilayer thickness. A new concept, geometrical frustration, was adopted to suppress multilayer crystallization, while maintaining intralayer molecular ordering, using an extended π-conjugated framework (πCore) asymmetrically substituted by an alkyl chain (πCore-Cn). Blade-coating with a solution containing two kinds of πCore-Cns with different alkyl-chain lengths yields single-molecular bilayers (SMBs). The uniformity and size of fabricated SMBs are unprecedented compared to other self-assembly processes. The obtained SMBs afford organic thin-film transistors (TFTs) showing excellent device characteristics with high carrier mobility and low-voltage operation below 2 V. Additionally, the obtained TFTs also exhibit highly sharp on/off switching behavior characterized by the slope of drain current curve in subthreshold regime, which is close to the value of the theoretical limit known for general TFTs. This finding should pave the way for SMB-based ultrathin and super-flexible electronics.
Keywords: Self-Assembly / Molecular Bilayer / Organic Semiconductor / Printed Electronics / Organic Thin Film Transistors
Surface Structure of Insects: Irregularities and Functions
吉岡 伸也
<要旨> Some insects have submicron-sized structures on their surface. One example is the array of protrusions that can be found on the compound eye of moths and the wings of some cicadas. This kind of structure is called moth-eye structure or nano-pile structure and is known to have several functions such as anti-reflection, high water-repellancy, and a function preventing other insects from walking on. It is quite interesting that those functions are realized despite the structural irregularities; the height of the protrusions are not uniform but distributed and the lateral arrangements are far from the regular hexagonal array. This article reports a study on the relation between the structural irregularities and functions. Theoretical calculation and experiments revealed that the anti-reflection is robust to the structural irregularities.
Keywords: Moth Eye Structure / Biomimetics / Surface Structure
グローイングポリマー Polymer Science and I: A Personal Account
#I’ll Figure it Out
林 正太郎
<要旨> There are times when I’m spending my future without feeling a sense of crisis. You and I may not be confident in yourself or maybe afraid to fail. Still, I was positive about what I liked and always want to say “I’ll figure it out (nantokasuru)”.
高分子科学最近の進歩 Front-Line Polymer Science
Fine Synthesis and Functionalities of One-dimensional Polymers with Well-defined Threading Structures
正井 宏・寺尾 潤
Hiroshi MASAI, Jun TERAO
<要旨> Finely synthesized macromolecules have gained importance as their structures and functionalities can be tuned by precise engineering. Desired properties and functionalities have been imparted by controlling the nanoscale structures of such macromolecules. In particular, compounds with interlocked structures, such as rotaxanes and catenanes, have attracted attention because of their unique supramolecular structures. In such supramolecular structures, the mobility and freedom of the macrocycles are restricted on the axle and dependent on other macrocycles, imparting unique functionalities to the threading structures. Recently, the ultrafine engineering and the functionalities of threading structures have been reported for the development of synthetic methodologies of “defined” threading structures, based on the number and position of the cyclic molecules, which are not dispersed on the axle. Herein, we review the effective synthetic methodologies of one-dimensional polymers bearing threading structures and on functionalities derived from precise engineering by discussing the latest reports and trends.
Keywords: Supramolecular Chemistry / Rotaxane / Host-Guest Chemistry / Fine Synthesis