Abstract:In this paper, we propose a simple one-pot methodology for proceeding from atom transfer reaction-induced conventional free radical polymerization (AT-FRP) to atom transfer self-condensing vinyl polymerization (AT-SCVP) through manipulation of the catalyst phase homogeneity (i.e., CuBr/2,2'-bipyridine (CuBr/Bpy)) in a mixture of styrene (St), 4-vinyl benzyl chloride (VBC), and ethyl 2-bromoisobutyrate. Tests of the solubilities of CuBr/Bpy and CuBr2/Bpy under various conditions revealed that both temperature and solvent polarity were factors affecting the solubility of these copper complexes. Accordingly, we obtained different polymer topologies when performing AT-SCVP in different single solvents. We investigated two different strategies to control the polymer topology in one-pot: varying temperature and varying solvent polarity. In both cases, different fractions of branching revealed the efficacy of varying the polymer topology. To diversify the functionality of the peripheral space, we performed chain extensions of the resulting hyperbranched poly(St-co-VBC) macroinitiator (name as: hbPSt MI) with either St or tBA (tert-butyl acrylate). The resulting hyperbranched core star polymer had high molecular weights (hbPSt-g-PSt: Mn = 25,000, Đ = 1.77; hbPSt-g-PtBA: Mn = 27,000, Đ = 1.98); hydrolysis of the tert-butyl groups of the later provided a hyperbranched core star polymer featuring hydrophilic poly(acrylic acid) segments.
OPEN ACCESSPolymers 2014, 6 2553
Airline companies join airline alliances to cope with the high level of competition in the airline industry. However, pressure within an alliance is substantial. This study used competitor mapping and awareness-motivation-capability competitive dynamics to analyze airline alliances. The results revealed that alliances compete to recruit airline companies, and the power differences in the alliances are considerable; only a few of the airline companies within the alliance possess power. In addition, we interviewed 2 senior managers to confirm the results of the analysis. A detailed content analysis was performed to test each hypothesis. The findings revealed that companies with low market commonality and high resource similarity can cooperate through resource allocation. We also discovered that the main competitive action was derived from disallowing local airline companies to join an alliance. Leading companies in the alliance generally negotiated for the entire alliance indirectly. This research suggests that companies cooperate not only to control cost but also to increase service quality.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.