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Preface to the Complex Materials II Special Issue Hierarchically organized structures of multiphase materials not only give rise to a diverse range of fascinating properties in nature, they also underpin the structural stability and functional excellence of a variety of everyday products. While the hierarchical structures seen around us in nature have evolved over millions of years, the journey to use scientific knowledge to engineer everyday materials, such as fabricated foods and home and personal care products, only started since the last century. Consumer science, food science, and engineering became scientific disciplines only a few decades ago. Therefore, “designing” and “engineering” such material systems from first principles to deliver a desired functional performance and unique sensorial experience is a demanding scientific and engineering challenge. In the above context, “Multiscale Structures and Dynamics of Complex Systems” was seen to emerge as a unifying theme of research that comprehends and harnesses a wide range of scientific approaches to the world of fast-moving consumer goods of everyday use. A series of international conferences focused around the theme were envisaged in China, India, and the United Kingdom to foster interdisciplinary faceto-face interaction among scientists interested in the multiscale structures of man-made materials as well as biosubstrates/ systems. The first conference held in Beijing, China (in 2007) addressed the subject of “Designing Structured Materials for Functionality and Sensory Experience”. The proceedings of the same were published in Special Issue of Industrial & Engineering Chemistry Research in September 2008 (Vol. 47, No. 17, pp 6345-6485). The second international conference titled “Processes and Forces for Creation of Designer Materials with Multi-Scale Structures” was held in Bangalore, India September 4-5, 2008. The conference was co-sponsored by the following entities: Chinese Academy of Sciences (CAS); the Indian National Science Academy (INSA); the Institution of Chemical Engineers (IChemE); the Royal Academy of Engineering (RAE); the Indian Institute of Science (IISc), Bangalore; the Jawaharlal Nehru Centre of Advanced Scientific Research (JNCASR), Bangalore; and Unilever. The two-day conference brought together ∼80 leading academic and industrial research scientists from across the globe. The meeting focused on novel process engineering, and innovative deployment of external force-fields for the creation of designer materials with unique structural, functional, or sensory characteristics. The conference was focused under four broad themes: (i) Process Induced Structuring and Emergence of Novel Properties, (ii) Inspirational Learnings from Nature and Models of Biosystems, (iii) Material and Structure Manipulation through External Force Fields, and (iv) Self Assembly Through Manipulation of Phase Space. Collected in this special issue is a selection of scientific papers presented at this conference. They afford a glimpse of the recent progress in the creation of multiscale structures, as well as the potential challenges and opportunities. In the area of Process Induced Structuring, the papers focus on the creation of nanoparticles and droplets through the use of membrane emulsification and microchannel arrays. The key challenge in the area is in achieving a narrow size distribution with high throughputs. The paper by Lv et al. in this special issue discusses the optimization of various formulation parameters, including the choice and level of emulsifiers and oil phase, and precursor
as well as process parameters of cross-linking temperatures, trans-membrane pressures, and the number of passes. The paper by Yuan et al. in this special issue discusses the design of the cross-flow and rotating membrane technology, where high throughput could be achieved by optimizing the shape, orientation, and surface energy of the membrane pores. Also in this special issue, Kobayashi et al. has demonstrated the effect of channel and step structure in microchannel arrays to modulate the droplet shape between discoid to spherical. In the area of pattern formation, imprinting on curved surfaces using flexible stamps (Mukherjee et al., in this special issue) would open up possibilities for creating structural color or desired wettability behavior on various surface of practical interest. Alternatively, exploiting the natural length scales of the system by varying either (i) the process condition (e.g., manipulating the fractal dimension of fingering patterns by varying the lifting pressure (Sinha et al. in this special issue)) or (ii) the formulation space (e.g., manipulating the iridescence of lamellar phases through use of cosurfactants (Dastidar et al. in this special issue) or the microemulsion phase behavior of a common anionic surfactant, NaLAS, through the incorporation of organic salts (Rout et al. in this special issue)) also provides novel avenues for microstructure creation and property manipulation. Under the theme of inspirational learning from nature, the paper by Ramachandra et al. in this special issue reviews the prospect of harvesting oil from diatoms by altering them to actively secrete oil products through either biochemical engineering or genetic engineering of live diatoms. Designing multiscale structures really starts with structural organization at a molecular/macromolecular level. The unfolding of a double-domain protein, Rhodanase, as a function of temperature, has been probed by molecular dynamics simulation studies by Ren et al., where the dynamics of the unfolding process as well as the emergence of higher solvophilic behavior has been reported. Finally, the paper by Muralidharan et al. in this special issue discusses the development of a rheological model for polymeric dispersions and gels that incorporate the practically relevant effects of particle size distribution and surface forces. The range of topics covered by this special issue are united by the theme of structure manipulation at multiple length scales leading to emergence of novel and desirable properties as a result of the same. The various “levers” for creation and manipulation of hierarchical structures as discussed in these papers can be harnessed for the creation of microstructures with desired functional and sensorial performance of food and home and personal care products with an ultimate aim of contributing to and raising the quality of people’s lives. A conference, followed by the special issue of this journal, covering topics of such diversity and unity cannot be achieved without the enduring support and promotion of many people and the financial support of Unilever Plc. We are indebted to Dr. R. A. Mashelkar (President, Global Research Alliance, and President, Institution of Chemical Engineers, UK), Prof. Jinghai Li (Vice President, Chinese Academy of Sciences, China), and Prof. Lynn Gladden (Shell Professor and Head, Department of Chemical Engineering, University of Cambridge, UK), who served as the senior advisors of the conference. We would like to acknowledge various committees of the conference: the Scientific Committee, chaired by Prof. Jim Darwent (The
10.1021/ie901168h CCC: $40.75 2009 American Chemical Society Published on Web 09/09/2009
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University of Liverpool, UK); Prof. V. M. Naik (Indian Institute of Technology, Bombay, India); Prof. K. S. Gandhi (Indian Institute of Science, Bangalore, India); Dr. B. D. Kulkarni (National Chemical Laboratory, India); Prof. Guangsheng Luo (Tsinghua University, Beijing, China); Prof. Guanghui Ma (Institute of Process Engineering, China); Dr. Stephen Moore (Unilever Research, Colworth, U.K.); Dr. Eddie Pelan (Unilever Research, The Netherlands); Dr. Janhavi Raut (Unilever Research Bangalore, India); Prof. Jonathan Seville (University of Warwick, UK); Prof. Ashutosh Sharma (Indian Institute of Technology, Kanpur, India); Prof. Dominic Tildesley (Unilever Research, Port Sunlight, UK); and the Organizing Committee, chaired by Dr. Vilas Sinkar (Unilever Research Bangalore, India) and consisting of Dr. R. Venkataraghavan (Unilever Research Bangalore, India), Dr. Guoping Lian (Unilever Research, Colworth, U.K.), Dr. David Liu (Unilever Research, China), and Prof. Wei Ge (Institute of Process Engineering, China). Finally, we would like to thank the oral and poster presenters, as well as the chairmen of the conference sessions. Many associates from Unilever Research Bangalore helped the
administration of the conference, and their assistance is acknowledged.
Janhavi S. Raut UnileVer Research India, Whitefield, Bangalore 560066, India
Guoping Lian UnileVer Research Colworth, Bedford MK44 1LQ, United Kingdom
Jim Darwent Department of Chemistry, The UniVersity of LiVerpool, LiVerpool L69 3BX, United Kingdom IE901168H
