Benzocyclobutene and its derivatives

Klundt, Irwin L.

doi:10.1021/cr60266a002

Cited by 156 publications

(64 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…,13,33−35 catalysis,12,36,37 small molecule and acid release,16,34,38 and soft devices. 39 ■ ASSOCIATED CONTENT * S Supporting Information Sonication experiments; IR and GPC-MALS characterization; rheology (PDF).…”

mentioning

confidence: 99%

Mechanochemical Strengthening of a Multi-mechanophore Benzocyclobutene Polymer

2015

View full text Add to dashboard Cite

The mechanical stresses that materials experience during use can lead to aging and failure. Recent developments in covalent mechanochemistry have provided a mechanism by which those stresses can be channeled into constructive, rather than destructive, responses, including strengthening in materials. Here, the synthesis and mechanical response of a polymer containing multiple benzocyclobutene (BCB) mechanophores along its backbone are reported. When solutions of the BCB polymer were exposed to the normally destructive elongational flow forces generated by pulsed ultrasonication, the number of intermolecular bond-forming reactions was greater than the number of bondbreaking reactions, leading to a net increase in polymer molecular weight. The molecular weight increase could be turned into gelation by introducing a bismaleimide cross-linker that reacts with the ortho-quinodimethide intermediate generated by mechanically assisted ring opening of the BCB mechanophores and using polymer concentrations in excess of the critical overlap concentration. Unlike a previous mechanically induced gelation of a mechanophore-based polymer, the BCB cross-linking requires no ionic components and represents an attractive, second platform for stress-strengthening materials.T he inevitable stress that almost all materials experience during use leads in many cases to bond breakage, materials aging, and failure, as is reflected in both polymer solutions 1 and solid state polymers. 2 To solve this problem, biological materials have evolved to have the ability to remodel and become stronger in response to otherwise destructive forces. 3,4 This form of mechanical adaptation has provided significant inspiration to current synthetic polymer chemistry efforts. Our group has recently demonstrated that the activation of multiple gem-dibromocyclopropane (gDBC) mechanophores 5 embedded along a polybutadiene backbone turns otherwise destructive chemical responses into constructive responses. 6 When the polymer was exposed to large forces, through either pulsed ultrasonication of polymer solutions or the extrusion of bulk materials, the gDBCs undergo electrocyclic ring-opening reactions to form 2,3-dibromoalkenes that react intermolecularly with carboxylate nucleophiles. The number of intermolecular bond-forming reactions exceeds the number of bond-breaking reactions and leads to a cross-linked polymer network. 6 While the gDBC system represents an important first example of mechanophore-based self-strengthening, the ultimate utility of the approach will depend on the ability to create mechanophore-based systems that match the demands of a particular application. To that end, we sought to develop multi-mechanophore polymers that might overcome the relatively low reactivity of the 2,3-dibromoalkene, 6 the irreversibility of gDBC ring opening in the absence of crosslinking, and the presence of ionic reactants.Because of the substantial recent activity in the realm of covalent polymer mechanochemistry, 7−9 and especially the exploration of mechanophor...

show abstract

mentioning

confidence: 99%

Mechanochemical Strengthening of a Multi-mechanophore Benzocyclobutene Polymer

2015

View full text Add to dashboard Cite

show abstract

“…5 z Verbindungen mit einem ahnlichen mesomeren Vierring-System erhielten wir bei der Umsetzung von (11) mit C hinaldinium-jodiden. In Tabelle …”

Section: Reaktionen Der Phenylcyclobutendioneunclassified

Zur Chemie der Phenylcyclobutendione

Ried

Schmidt

1972

Angewandte Chemie

View full text Add to dashboard Cite

Phenylcyclobutendione zeichnen sich durch leichte Zugänglichkeit und hohe Stabilität aus. Je nach der Natur des in 3‐Stellung befindlichen Substituenten R können sie formal als vinyloge Carbonsäureabkömmlinge (R = Halogen, OCH3, OH, SH) oder als α,β‐ungesättigte Diketoverbindungen (RH, Alkyl, Aryl) angesehen werden. Ihr reaktives Verhalten rechtfertigt diese Betrachtungsweise. Ringverengungs‐, Ringerweiterungs‐ und Ringöffnungsreaktionen werden beschrieben.

show abstract

“…[1][2][3][4][5][6][7][8] The striking feature of benzocyclobutenes is the potential for ring-opening reactions leading to reactive ortho-quinodimethanes, which readily enter into cycloaddition reactions. In order to eliminate the planes of symmetry present in ortho-quinodimethanes, metal π complexes of benzocyclobutene and substituted derivatives have been prepared and investigated, both by ourselves and by Kündig's group.…”

Section: Introductionmentioning

confidence: 99%