Kazuyuki Horie

Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)

This document defines terms related to the structure and processing of inorganic, polymeric, and inorganic-organic hybrid materials from precursors, through gels to solid products. It is divided into four sections - precursors, gels, solids, and processes - and the terms have been restricted to those most commonly encountered. For the sake of completeness and where they are already satisfactorily defined for the scope of this document, terms from other IUPAC publications have been used. Otherwise, the terms and their definitions have been assembled in consultation with experts in the relevant fields. The definitions are intended to assist the reader who is unfamiliar with sol-gel processing, ceramization, and related technologies and materials, and to serve as a guide to the use of standard terminology by those researching in these areas.

DEFINITIONS OF TERMS RELATING TO REACTIONS OF POLYMERS AND TO FUNCTIONAL POLYMERIC MATERIALS (IUPAC Recommendations 2003)

The document defines the terms most commonly encountered in the field of polymer reactions and functional polymers. The scope has been limited to terms that are specific to polymer systems. The document is organized into three sections. The first defines the terms relating to reactions of polymers. Names of individual chemical reactions are omitted from the document, even in cases where the reactions are important in the field of polymer reactions. The second section defines the terms relating to polymer reactants and reactive polymeric materials. The third section defines the terms describing functional polymeric materials.

Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials

This document defines terms related to the structure and processing of inorganic, polymeric, and inorganic-organic hybrid materials from precursors, through gels to solid products. It is divided into four sections-precursors, gels, solids, and processes- and the terms have been restricted to those most commonly encountered. For the sake of completeness and where they are already satisfactorily defined for the scope of this document, terms from other IUPAC publications have been used. Otherwise, the terms and their definitions have been assembled in consultation with experts in the relevant fields. The definitions are intended to assist the reader who is unfamiliar with sol-gel processing, ceramization, and related technologies and materials, and to serve as a guide to the use of standard terminology by those researching in these areas.

Isomeric Biphenyl Polyimides. (I) Chemical Structure-property Relationships

A series of polyimides (PIs) were prepared from three biphenyltetracarboxylic dianhydrides (BPDA) isomers, i.e., 3,3′,4,4′-BPDA (s-BPDA), 2,3,3′,4′-BPDA (a-BPDA), and 2,2′,3,3′-BPDA (iBPDA) with various diamines through the conventional two step process. Polymerization reactivity, solubility, and dynamic mechanical properties (T g, softening behavior, and storage modulus at glassy state) were compared between PIs derived from these BPDA isomers and para/meta diamine isomers. The solubility in NMP increased as follows: i-BPDA-PI > a-BPDA-PI > s-BPDA-PI. The order is attributed to semi-crystalline and fully amorphous morphologies of s-BPDA-PI and other isomeric BPDA-PIs, respectively. The use of meta-diamines lowered the T g whereas the use of bent/distorted BPDA isomers enhanced the T g (s-BPDA-PI < a-BPDA-PI < i-BPDA-PI). The BPDA isomer effect on T g is based on the difficulty of obtaining internal rotation around the biphenyl linkages. The width of the DMA rubbery plateau region decreased in the order of i-BPDA < a-BPDA-PI < s-BPDA-PI, depending on the crystallinity and the extent of chain entanglement. In a-BPDA and i-BPDA-PI systems, PIs from metadiamines led to higher modulus than the corresponding PIs from para-diamines.

End-Crosslinking Gelation of Poly(amide acid) Gels studied with Scanning Microscopic Light Scattering

Network formation in the gelation process of end-crosslinked poly(amide acid) gels, which are the precursor of end-crosslinked polyimide gels, was studied by scanning dynamic light scattering. The gelation process is essentially non-reversible due to the formation of covalent bonds. The molecular structure formed in the gelation process is controlled by varying the equivalence ratio of end-crosslinker to oligomer during the preparation. It was found that a couple of relaxation modes are observed in the gelation point even for semi-rigid poly(amide acid) solutions. This is similar to flexible polymer solutions and convenient to characterize the molecular structure in the gelation processes. The fast mode is related to the cooperative diffusion process of the network structure formed by over lapped macromolecules, i.e., gel mode, which determines the averaged mesh-size of the network structure. The slow mode is related to the relaxation time of the formation of the transient network structure, which shows a slowing down close to the gelation point and disappears after gelation due to the formation of the permanent network structure.

Light-induced control of textures and cholesteric pitch in liquid crystals containing chromium complexes, by means of circular and linear polarized light

A nematic liquid crystal doped with a chiral dopant has a cholesteric texture with a regular pitch. The pitch is changed by variation of concentration of the dopant. We observed the appearance of a fingerprint texture on irradiation of a homeotropic mixed liquid crystal doped with a racemic chromium complex, Cr(Buacac)3, and an auxiliary chiral dopant, with right-circular polarized light (r-CPL); the fingerprint texture disappeared on irradiation with left-circular polarized light (l-CPL). We also measured a helical twisting power, βm, of the chromium complex from the cholesteric pitch of the mixed liquid crystal doped with optically resolved Λ -(Cr(Buacac)3; and clarified the relationship between the change in the cholesteric pitch and the quantum yield of the photoinversion reaction.

Control of ionic conductivity of ionic liquid/photoresponsive poly(amide acid) gels by photoirradiation

1,3-Dibutylimidazolium bromide was soaked into a polymer network prepared by condensation of 4-4-diaminoazobenzene, pyromellitic dianhydride and 1,3,5-tri(4-aminophenyl)benzene to form photoresponsive ion conductive gels.

Light-induced formation of curved needle texture by circularly polarized light irradiation on a discotic liquid crystal containing a racemic chromium complex

We have found that the discotic nematic liquid crystal, hexakis(4‐nonylphenylethynyl)benzene (HNEB), doped with the racemic chromium complex Cr(Ocacac)3, shows a novel straight‐needle texture with hexagonal columnar alignments, changing to a curved‐needle texture under irradiation of circularly polarized light (CPL). This novel phenomenon is specific to the mixture of HNEB and Cr(Ocacac)3. The formation of curved needles means that chiroselective photoinversion of racemic Cr(Ocacac)3 by CPL irradiation induces a needle direction change in a discotic liquid crystal. The change in chirality of Cr(Ocacac)3 in HNEB induced by CPL irradiation, and the resulting nano‐segregation of its enantiomers during cooling from the isotropic to mesophase of HNEB, are considered to influence changes in the alignment of columns and/or small domains of column aggregates in the discotic liquid crystal.

Definitions relating to stereochemically asymmetric polymerizations (IUPAC Recommendations 2001)

Asymmetric polymerization has been of interest to many academic and industrial polymer scientists, but no reference has been made by IUPAC explicitly to classification and definitions of reactions involving the asymmetric synthesis of polymers. This document presents definitions concerned with asymmetric and related polymerizations, with examples included to clarify the meaning of the definitions. Asymmetric polymerizations embrace two main categories, asymmetric chirogenic polymerizations and asymmetric enantiomer-differentiating polymerizations.

Mission and challenges of polymer science and technology

Following the first IUPAC Polymer Conference on the Mission and Challenges of Polymer Science and Technology (IUPAC PC2002), this article highlights and summarizes the historical development of polymer science and technology and the recent advances that have occurred and are occurring in the subject. It highlights the mission and challenges for the future, particularly as reflected in the papers presented at the conference and in the con- ference’s concluding panel discussion. The important role of IUPAC in defining and leading developments in polymer science and technology is also described. The central role of polymer science and technology and its close interactions with chemical, physical, and biological sciences are defined and discussed. The 21st century is shown to be the Age of Polymers.