Advanced Materials

Marzolin, Christian; Smith, Stephen P.; Prentiss, Mara; Whitesides, George M.

doi: 10.1002/(SICI)1521-4095(199805)10:8<571::AID-ADMA571>3.0.CO;2-Ppmid: N/A

Submicrometer patterns of glasses on a substrate have been created using a type of soft lithography. The method, which is complementary to photolithography and rapid ion etching, is described and examples of applications are given. The Figure shows a scanning electron micrograph of a membrane of titanosilicate glass after an aqueous suspension of 2 μm beads had passed through it.

Hu, Junmin; Beck, Rex G.; Westervelt, Robert M.; Whitesides, George M.

doi: 10.1002/(SICI)1521-4095(199805)10:8<574::AID-ADMA574>3.0.CO;2-Dpmid: N/A

The fabrication of arrays of Schottky diodes on p‐type silicon is described using a representative soft lithographic technique: micromolding in capillaries (MIMIC). It is demonstrated that soft lithography is compatible with multilayer fabrication of electronically functional structures. The characteristics of the diodes were found to be similar to those fabricated by photolithography. The advantages and limitations of MIMIC are outlined, with particular attention being paid to the degree of registration of features that can be achieved.

Rabinovich, Leonid; Gun, Jenny; Lev, Ovadia; Aurbach, Doron; Markovsky, Boris; Levi, Michael D.

doi: 10.1002/(SICI)1521-4095(199805)10:8<577::AID-ADMA577>3.0.CO;2-1pmid: N/A

The anode in lithium‐ion batteries is usually a carbonaceous material, e.g., graphite powder or fibers held together by a binding polymer. A new type of reversible lithium anode is demonstrated: sol‐gel‐derived carbon ceramic electrodes (CCEs), such as that shown in the scanning electron micrograph in the Figure. The response of the CCEs is compared to that of a conventional polymer–graphite electrode.

Maoz, Rivka; Sagiv, Jacob

doi: 10.1002/(SICI)1521-4095(199805)10:8<580::AID-ADMA580>3.0.CO;2-Ppmid: N/A

A conceptually new type of multilayer self‐assembly is described and its practical feasibility demonstrated for silane multilayers. This self‐assembly permits more than a single monolayer to be added in a single assembly step, targeting of the bilayer self‐replication to specific bilayers (by “labeling”), and manipulation of the bilayer “labeling” such as to create variable sequence patterns of replicative film growth. It is hoped that further developments will lead to the planned fabrication of a large variety of artificial layer materials with predefined molecular organization starting from a precursor monolayer.

Burghard, Marko; Duesberg, Georg; Philipp, Guenther; Muster, Joerg; Roth, Siegmar

doi: 10.1002/(SICI)1521-4095(199805)10:8<584::AID-ADMA584>3.0.CO;2-9pmid: N/A

For applications of carbon nanotubes in electronic components site‐specific assembly of nanotubes onto patterned substrates is required. The Figure shows, as an example, a surface modification that favors attachment of nanotubes to an electrode (Au/Pd). The adsorbed nanotube (gray) has a partial surfactant shell and there is an alkanethiol monolayer between the nanotube and electrode. The Si/SiO2 wafer is unaffected.

Misaki, Yohji; Kochi, Tatsuro; Yamabe, Tokio; Mori, Takehiko

doi: 10.1002/(SICI)1521-4095(199805)10:8<588::AID-ADMA588>3.0.CO;2-Upmid: N/A

The selenium analogue of the unsubstituted bis‐fused tetrathiafulvalene TTP (2,5‐bis(1,3‐dithiol‐2‐ylidene)‐1,3,4,6‐tetrathiapentalene) has been synthesized and the conducting properties and crystal structure of its molecular complexes are presented. TTP is a promising π‐electron framework for the preparation of organic molecular metals because of its strong tendency to yield radical cation salts that retain metallic conductivity down to liquid helium temperature regardless of the counteranion. However, only poorly characterized derivatives of the selenium‐based TTP had been prepared previously.

Shafi, Kurikka V. P. M.; Gedanken, Aharon; Prozorov, Ruslan

doi: 10.1002/(SICI)1521-4095(199805)10:8<590::AID-ADMA590>3.0.CO;2-Lpmid: N/A

Stabilization of magnetic fluids can be achieved by coating the particles, e.g., amorphous cobalt nanoparticles, with long‐chain surfactant molecules, e.g., oleic acid. What is the driving mechanism? It is shown that the particles try to self‐organize, growth proceeding until uniform acicular‐shaped particles (see Figure) are reached. A mechanism is proposed and the role of the surfactant discussed.

Huang, Wei; Meng, Hong; Yu, Wang‐Lin; Gao, Jun; Heeger, Alan J.

doi: 10.1002/(SICI)1521-4095(199805)10:8<593::AID-ADMA593>3.0.CO;2-9pmid: N/A

An n‐doped‐type light‐emitting polymer that emits blue light with a very high photoluminescence efficiency (79%) is reported. Its synthesis and properties are described and its potential for application in polymer light‐emitting diodes (PLEDs) has been checked by the construction of a single‐layer LED. All polymers commonly used in PLEDs are typical p‐doped‐type polymers with a greater tendency to transport holes than electrons, this charge imbalance being a key limit to increasing the electroluminescence efficiency of PEDs. This work demonstrates that n‐doped‐type polymers suitable for PLEDs can be found.

Teranishi, Toshiharu; Kiyokawa, Iwao; Miyake, Mikio

doi: 10.1002/(SICI)1521-4095(199805)10:8<596::AID-ADMA596>3.0.CO;2-Ypmid: N/A

Chemical control over the size of nanoparticles is a prerequisite for their application. The synthesis of protective polymers having cyano or mercapto groups (e.g., MMS‐NVP, see Figure) is reported, together with the influence of these polymers on the size and size distribution of gold nanoparticles synthesized by KBH4; reduction. The results obtained using a linear protective polymer without a cyano or mercapto group are compared.

Raymond, François; Césare, Nicolas Di; Belletête, Michel; Durocher, Gilles; Leclerc, Mario

doi: 10.1002/(SICI)1521-4095(199805)10:8<599::AID-ADMA599>3.0.CO;2-Mpmid: N/A

The chromic properties of conjugated polymers, i.e., the shift in their optical spectra with various parameters, make them of interest for sensors. In order to test the prediction that poly(3,3′‐di(alkylthio)‐2,2′‐bithiophene)s should exhibit thermochromic features and to verify the simple theoretical model behind this prediction, the synthesis of the butyl member of the series and the characterization of its thermochromic properties are reported. It is concluded that the rational design of novel chromic conjugated molecules is possible.