김종만 교수

Technological advances made in constructing high-resolution instrumentation have enabled fabrication of sophisticated counterfeit products. As a result, the need to develop novel anti-counterfeiting materials and systems is greatly increasing. Accordingly, various functional materials that display distinct chemical, physical as well as optical and electrical properties have been investigated for preventing and detecting counterfeiting. In this feature article, we describe recent strategies that

Owing to the color (blue-to-red) and fluorescence (non-to-fluorescent) changes that take place in response to environmental perturbations, conjugated polydiacetylenes (PDAs) have been actively employed as sensory materials for the detection of biologically-, environmentally- and chemically-important target molecules. Until recently, the majority of PDA sensors have been prepared in the form of aqueous suspensions or Langmuir-type thin films on solid substrates. In order to overcome the limitatio

Inkjet-printable aqueous suspensions of conjugated polymer precursors are developed for fabrication of patterned color images on paper substrates. Printing of a diacetylene (DA)-surfactant composite ink on unmodified paper and photopaper, as well as on a banknote, enables generation of latent images that are transformed to blue-colored polydiacetylene (PDA) structures by UV irradiation. Both irreversible and reversible thermochromism with the PDA printed images are demonstrated and applied to fl

While a large variety of conjugated polymers exist, polydiacetylenes (PDAs) remain a major research area among scientists due to their interesting optical, spectral, electronic, and structural properties. Heavily reviewed in regards to their stimuli responsive properties, much is known about the assortment of sensing and detection capabilities of PDAs. In this article, we look more upon the structural diversities of polydiacetylenes that have been achieved in recent years, particularly from a hi

"Paper" has greatly contributed to the development and spread of civilization. Even in today's "digitalized" world, paper continues to play a key role in socioeconomic growth, as is evidenced by the growth in global paper consumption. Unfortunately, the use of paper has its cost in terms of the exhaustion of world's natural resources. Consequently, new, cost-effective technologies that preserve natural resources are required for this purpose. Functional materials have revolutionized the way peop

The colorimetric reversibility of polydiacetylene supramolecules, derived from a variety of functionalized diacetylenic lipids, has been subjected to detailed investigation. In an earlier effort, it was shown that polydiacetylene vesicles prepared from PCDA-mBzA 1, bearing terminal m-carboxyphenylamido groups, display complete reversibility upon thermal stimulation [J. Am. Chem. Soc. 2003, 125, 8976]. The origin and nature of reversible thermochromism in these systems have been elucidated in-sit

Self-assembled diacetylene vesicles were spotted and immobilized on aldehyde-modified glass substrates using conventional microarray technology. Irradiation of the immobilized diacetylenes allowed generation of nonfluorescent "blue-phase" polydiacetylene (PDA) arrays. Specific interaction of the PDA vesicle arrays with carbohydrates or poly(acrylic acid) solutions afforded fluorescent profiles.

Abstract Polydiacetylenes (PDAs), a family of highly π‐conjugated polymers, have unique characteristics associated with their ability to self‐assemble. Disruption of the extensively delocalized enyne backbones of molecularly ordered PDA sidechains induces a blue‐to‐red color change, which has been elegantly applied in the design of chemosensors. Recently, colorimetrically reversible PDAs have received significant attention, not only to gain a better understanding of the fundamentals of PDA chrom

As they have been designed to undergo colorimetric changes that are dependent on the polarity of solvents, the majority of conventional solvatochromic molecule based sensor systems inevitably display broad overlaps in their absorption and emission bands. As a result, colorimetric differentiation of solvents of similar polarity has been extremely difficult. Here we present a tailor-made colorimetric and fluorescence turn-on type solvatochromic sensor that enables facile identification of a specif

Exceptional challenges have confronted the rational design of colorimetric sensors for saturated aliphatic hydrocarbons (SAHCs). The main reasons for this difficulty are the extremely nonpolar nature of these targets and their lack of functional groups that can interact with probes. By taking advantage of a mechanochromic conjugated polydiacetylene (PDA) and the hydrocarbon‐induced swelling properties of polydimethylsiloxane (PDMS), a sensor film that enables simple, colorimetric differentiation

Recently, the development of directly writable techniques for depositing functional materials on solid substrates has received great attention. These pen‐on‐paper approaches enable generation of diverse patterned images on solid substrates in a flexible, easy handling, and inexpensive manner. Herein, the development of a directly writable conjugated polymer is described. Mechanically, drawable colorimetric polydiacetylene (PDA)–wax composites are readily fabricated by using a simple mixing‐moldi

Hydrochromic materials find great utility in a wide range of applications including humidity sensing and measuring the water contents of organic solvents, as well as substrates for rewritable paper and human sweat pore mapping. Herein, an inkjet printable diacetylene (DA) is described that can be transformed by UV irradiation to a hydrochromic‐conjugated polymer on conventional paper. Specifically, an amphiphilic DA that contains an ­imidazolium ion head‐group is found to be compatible with a co

“Digitalization” represents one approach to shift society's dependence on paper‐based communication. However, thus far, this tactic has not had a significant impact on global paper consumption, which has risen over the past few decades. The escalating demand of paper making and consumption has resulted in an intensified negative effect on the environment. Because of this, the development of rewritable paper or erasable ink appears to be an ideal approach to alleviate the increasing demand for pa

Abstract A combinatorial approach for the colorimetric differentiation of organic solvents is developed. A polydiacetylene (PDA)‐embedded electrospun fiber mat, prepared with aminobutyric acid‐derived diacetylene monomer PCDA‐ABA 1, displays colorimetric stability when exposed to common organic solvents. In contrast, a fiber mat prepared with the aniline‐derived diacetylene PCDA‐AN 2 undergoes a solvent‐sensitive color transition. Arrays of PDA‐embedded microfibers are constructed by electrospin