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Non-covalent interactions imposed by polar groups affect the properties of polyisoprene in various ways. But traditional modification method only led to randomly functionalized product which ignored the effects of sequence and location of polar groups. In this work, by using a novel polar monomer hydroxyl-myrcene (HMY), hydroxyl group terminally (BC–OH) and randomly functionalized (RC-OH) polyisoprene copolymers were successfully obtained. Due to the different hydroxyl group sequences, BC-OH and RC-OH shows different morphologies and rheological properties. Furthermore, polyhedral oligomeric silsesquioxanes (POSS) with urea bond was used as nanofiller to attach on BC-OH and RC-OH and generating BC-POSS and RC-POSS, respectively. The assembly of POSS and the formation of urea hydrogen bond will occur collaboratively. As a result, BC-POSS and RC-POSS showed distinct morphological properties and thermal stabilities. It is found that ordered urea bonds were formed in RC-POSS, while less ordered urea bonds were formed in BC-POSS. Overall, these results suggest that the tailoring of polar group sequence in polyisoprene copolymers could be a promising avenue for tuning polyisoprene performance via tuning aggregation behaviors of the polar groups. Image 1 • Terminally and randomly functionalized polyisoprene copolymers were obtained via polar monomer copolymerization. • BC-OH and RC-OH exhibit ball-like and continuous network morphologies, respectively. • POSS nanofillers with urea bonds formed spherical aggregates in BC-POSS and fibrous aggregates in RC-POSS. • Ordered urea bonds were formed in RC-POSS, while less ordered urea bonds were formed in BC-POSS. [ABSTRACT FROM AUTHOR]

This study aims to examine research collaboration between universities and industry in the field of computer science using bibliometric methods. To further understand the impact of individual countries on university-industry (UI) collaboration, data were retrieved from the computer science journal papers included in the Science Citation Index and published during the period 2002--2011. The density, degree centrality, betweenness centrality, and closeness centrality of UI collaborative networks were calculated in order to ascertain the core countries involved in international UI collaboration. This study investigates university-industry collaborative papers (UI papers) at the global and country levels. At the global level, the results show an increasing trend in UI papers and a stable UI collaboration ratio during the last decade. The average number of authors for UI papers is 4.13, which is higher than that for all other papers. Most UI papers result from two-institution collaboration, but we observed an increase in the number of UI papers produced by multiple universities and industrial entities. At the country level, the results also show that international UI paper collaboration has intensified. Meanwhile, the USA is the dominant collaborative partner with many countries and has produced the highest number of UI papers globally. [ABSTRACT FROM AUTHOR]

Elastomeric vitrimers with covalent adaptable networks are promising candidates to overcome the intrinsic drawbacks of conventional covalently-crosslinked elastomers; however, most elastomeric vitrimers show poor mechanical properties and require the addition of exogenous catalysts. Herein, we fabricate a catalyst-free and mechanically robust elastomeric vitrimer by constructing a segregated structure of sodium alginate (SA) in the continuous matrix of epoxidized natural rubber (ENR), and further crosslinking the composite by exchangeable hydroxyl ester bonds at the ENR-SA interfaces. The manufacturing process of the elastomeric vitrimer is facile and environmentally friendly without hazardous solvents or exogenous catalysts, as the abundant hydroxyl groups of the segregated SA phase can act as catalyst to activate the crosslinking reaction and promote the dynamic transesterification reaction. Interestingly, the segregated SA structure bears most of the load owing to its high modulus and small deformability, and thus ruptures preferentially upon deformation, leading to efficient energy dissipation. Moreover, the periodic stiffness fluctuation between rigid segregated SA phase and soft ENR matrix is beneficial to the crack-resisting. As a result, the elastomeric vitrimer manifests exceptional combination of catalyst-free, defect-tolerance, high tensile strength and toughness. In addition, the elastomeric vitrimer also exhibits multi-shape memory behavior which may further broaden its applications. [ABSTRACT FROM AUTHOR]

Interfacial interaction is of crucial importance for polymer nanocomposites. To improve interfacial interaction between graphene (GE) and isoprene rubber (IR), we grafted a silane coupling reagent, (bis-[γ-(triethoxysilyl) propyl]-etrasulfide), onto graphene oxide (GO). The modified GO was mixed with IR by solution blending and then reduced in situ to prepare IR/surface modified GE nanocomposites (IR/SGE). Raman mapping illustrates that the bound rubber on SGE is much thicker than that on unmodified GE, suggesting a strong interfacial interaction between SGE and IR. As a result, IR/SGE shows slower chain dynamics and lower strain-induced crystallinity than IR/GE. However, on-line Raman measurements show that the G band of IR/SGE shifts more noticeably during uniaxial tensile deformation than that of IR/GE; this suggests more efficient load transfer between SGE and IR. Consequently IR/SGE has better mechanical properties than IR/GE. [ABSTRACT FROM AUTHOR]