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Poly(4-vinylpyridine)-block-polystyrene (P4VP-b-PS) is an ideal amphiphilic diblock copolymer for potential applications in emulsion polymerization, colloid stabilization and microreactors, and the self-assembly ability also helps P4VP-b-PS to find wide applications in nanolithography, catalysis, molecular templating, and drug delivery. In this work, the non-covalent functionalization of single-walled carbon nanotubes (SWCNTs) with P4VP-b-PS in CO2-expanded liquids (CXLs) is reported. It is found that P4VP-b-PS stabilized SWCNTs showed better dispersion in organic solvent. Raman spectra indicated that there exist interactions between SWCNTs and P4VP-b-PS chains. Furthermore, the structure and morphology of P4VP-b-PS/SWCNTs composite were examined, focusing on P4VP-b-PS concentration and the pressure of CXLs. It is found that the P4VP-b-PS wrapping patterns undergo a remarkable morphological evolution from dotted coating crystals to compact kebabs, and then to helical patternings by facile pressure tuning in the high polymer concentration series. In other words, the CXLs method enables superior control of the P4VP-b-PS crystallization patternings on SWCNTs. What is more, the CXL-assisted P4VP-b-PS crystal growth mechanism on SWCNT is investigated. The crystal growth exhibited a pressure-switchable mechanism, i.e., the dominating mechanism switches from “soft epitaxy” (kebabs) at pressures below the threshold pressure to “normal epitaxy” (helicals) at higher pressure above the threshold value. We believe these studies would reveal great potential for P4VP-b-PS in building up functional structures in CXLs that are responsive to environmental stimuli.

With the rise in the popularity of web-based education, there is a pressing need for the design of web-based systems that are domain-specific. This need is particularly acute for the domain of second language education, where generic web-based systems fall short of fulfilling the potential of the Internet for meeting the particular challenges faced by language learners and teachers. A novel interactive online environment is described which integrates the potential of computers, Internet, and linguistic analysis to address the highly specific needs of second language composition classes. The system accommodates learners, teachers, and researchers. A crucial consequence of the interactive nature of this system is that users actually create information through their use, and this information enables the system to improve with use. Specifically, the essays written by users and the comments given by teachers are archived in a searchable online database. Learners can do pinpoint searches of this data to understand their individual persistent difficulties. Teachers can do the same in order to discover these difficulties for individual learners and for a class as a whole. The architecture of the system makes possible a novel approach to corpus analysis of learner errors. Teachers' annotations of learner errors are exploited as bootstraps which can lead to the incremental uncovering of errors without the need to heavily error tag the learner corpus. Error analysis then feeds the design of online help content.