SUGAR BASED-BLOCK COPOLYMER SELF-ASSEMBLY: NANO-ORGANIZED THIN FILMS FOR TRANSISTOR MEMORY DEVICES – SWEETMEMORY

Nano-organized thin films that find applications in immerging nanotechnology (such as nanolithography, electronics, photonics…) are made today from synthetic polymers and more precisely from block copolymer (BCP) systems. Generally, these copolymers are derived from petroleum and their self-assembly is today limited to 30 nm resolutions (domain and size spacing). This feature is highly limitative for the development of new generation of flexible electronic memory devices with a higher storage capacity. The main reason of this size barrier stems from a relative weak interfacial incompatibility represented by the ki*N (Flory-Huggins constant) between both synthetic blocks. The aim of this proposal is the design and the nanofabrication of novel oligosaccharide-based block copolymers with highly segregating strength and strong charge-storage ability to control the domain size for the next generation of high-resolution patterning – e.g. sub-10nm electrets for OFET memory devices prepared on biodegradable substrates. Indeed, BCP present the pronounced ability to self-assemble into various ordered nanostructures (lamellae, cylinders, spheres, gyroids) due to the repulsion between the chemically connected blocks, being considered a good way to control trapping moieties in nanodomains. Thus, it is crucial to pursue BCP that have small N and high "ki" values to minimize self-assembled feature sizes for the high retention capability of OFET memory. The synthetic approaches will combine chemo-selective functionalization and state of the art “click chemistry” including metal-free approach.

In relation with this project, very promising and important steps have been achieved very recently (2010-2014) by R. Borsali’s group at CERMAV showing preliminary results on nanostructured thin films made from glycopolymer systems whose nano-patterning is approaching 5-10 nm with sharp interfaces (Patent #1: PCT/FR2011/051843 (CNRS) 2010, World Extension 2011, Patent #2: (CNRS/UT, USA, 2011); Langmuir 2011, 27, 4098–4103; ACS Nano, 2012; Macromolecules, 2013, 46 (21), 8932-8940, Macromolecules 2013, 46 (21), 8509-8518. Macromolecules 2013, 46 (4), 1461-1469, ACS Macro Lett. 2012, 1 (12),1379-1382).

In parallel, Prof. W.C. Chen’s group has gained a great expertise in the development of straightforward strategies to design donor-acceptor block-copolymers for controlling morphology of self-assembled nanostructures and physical properties with an interest in memory applications (Adv. Funct. Mater. 2010, 20, 3012.; Macromol. Rapid Commun., 2011, 32, 528.; Soft Matter, 2011,7, 8440.;Chem. Commun., 2012, 48, 383.; ACS Macro Lett., 2013,2, 555.; Adv. Funct. Mater., 2013, 23, 4960).

Thus the interdisciplinary approach involves a strong collaboration between France (Cermav : Dr R. Borsali and collaborators) and Taiwan (Prof. Wen-Chang Chen, National Taiwan University and collaborators). The proposal constitute a clever mix with leader teams in the advanced building of self-assembled sugar-based hybrid block copolymers featured by sub_nano-organized thin films and on the synthesis, morphology, optoelectronic properties and applications of side-chain conjugated block copolymers. This “window” of opportunity will certainly open new horizons for the valorization of bio-sourced functional nanomaterials useful for flexible electronic devices. The two groups have already published preliminary work in Advanced Functional Materials DOI: 10.1002/adfm.201304297: “High-Performance Nonvolatile Transistor Memories of Pentacence Using the Green Electrets of Sugar-based Block Copolymers and Their Supramolecules” Y-C. Chiu, I. Otsuka, S. Halila, R. Borsali and W-C. Chen. This article is being considered to be featured on issue cover page of Adv. Funct. Mater.