New multiphase architecture from statistical copolymers by cooperative hydrogen bond formation

Hilger, Christopher; Stadler, Reimund

doi:10.1021/ma00209a037

Cited by 65 publications

(48 citation statements)

References 5 publications

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“…A model is proposed that explains the formation of the cage particles in terms of ordered and selective interactions of segregated populations of micelles. This model, based on the solution behavior of amphiphiles (13), is consistent with models recently proposed for other amphiphilic copolymers (14,15) and with the currently understood behavior of amphiphilic lipids in aqueous solution.…”

supporting

confidence: 90%

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

Cudd¹,

Bhogal²,

O’Mullane³

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

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When dissolved in N,N-dimethylformamide and then dialyzed against phosphate-buffered saline, A-B-A block copolymers composed of poly[M-(2-hydroxyethyl)-LglutamineJ-block-poly(v-benzyl-L-glutamate)-block-poly[N5-(2-hydroxyethyl)-L-glutamineJ form particles. The particles are cage-like structures with average diameters of 300 am (average polydispersity, 0.3-0.5). They are stable in aqueous solution at 4(C for up to 3 weeks, at which time flocculation becomes apparent. Negative staining and freeze-fracture electron microscopy suggest that cage-like particles are formed by selective association of segregated micelle populations. A model of particle formation is presented in which B blocks form micelles in dimethylformamide. On dialysis against an aqueous solution, the extended A blocks then associate intermolecularly to form rod-shaped micelles, which connect the B block micelles. The result is a meshed cage-like particle. The implications of these observations on the aggregation behavior of polymeric surfactants in dilute solution are discussed.Amphiphilic block copolymers, containing hydrophobic and hydrophilic components, exhibit surfactant behavior (1, 2) and may form micelles. Micelles are also formed by block copolymers in organic solvents when one of the blocks is insoluble (3). In this case, the insoluble blocks form the micelle core and are surrounded by the soluble blocks. Elongated or rod-shaped micelles rather than globular micelles may be formed by block copolymers in dilute solution (4, 5). These elongated structures may be considered to be extended tubes having insoluble cores surrounded by soluble shells. Such micelles have been described for systems such as polystyrene-block-poly(methylmethacrylate) in toluene/furfuryl alcohol, polystyreneblock-polybutadiene-block-polystyrene copolymer in isopropyl acetate (6), polystyrene-block-polybutadiene in homopolystyrene (7), and polystyrene-block-polyisoprene copolymer in N,N-dimethylacetamide (8). Elongated micelles have been documented by electron microscopy (9).In existing studies of amphiphilic polypeptide block copolymers, little attention has been given to micelles formed in dilute solution by these surfactants (10, 11). Only recently has this problem been considered for A-B, A-B-A, and A-B-C block copolymers incorporating flexible and rigid, rod-like blocks in solvents good for the flexible blocks but that are nonsolvents for the rod-like blocks (12).We have observed that a poly(amino acid)-based A-B-A block copolymer will form stable cage-like particles in dilute aqueous solution when prepared through the solvent N,Ndimethylformamide (DMF). A model is proposed that explains the formation of the cage particles in terms of ordered and selective interactions of segregated populations of micelles. This model, based on the solution behavior of amphiphiles (13), is consistent with models recently proposed for other amphiphilic copolymers (14, 15)

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supporting

confidence: 90%

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

Cudd¹,

Bhogal²,

O’Mullane³

et al. 1991

Proc. Natl. Acad. Sci. U.S.A.

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“…The deuterated butadiene was obtained by ^^H-exchange on butadienesulfone and subsequent thermal decomposition. The synthesis of the functional groups is described elsewhere (12,13).…”

Section: Methodsmentioning

confidence: 99%

Orientation Behavior of Thermoplastic Elastomers Studied by ²H-NMR Spectroscopy

Dardin

Boeffel

Spieß

et al. 1995

ACS Symposium Series

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In functionalized polybutadienes extended supramolecular junction zones are formed by self-aggregation of functional units via directed hydrogen bonds. The unusual 2 H-NMR lineshapes as well as the large quadrupolar splittings indicate highly oriented network chains in the stretched samples. Angular dependent measurements and inversion--recovery experiments prove the uniaxiality of the deformation and the homogeneity of the polymer backbone dynamics. A quantitative analysis of the lineshapes according to present theories is not possible but the spectra can be understood assuming a gradient of orientation alone individual network chains. For the highest strain ratios of λ>10 the 2H-NMR spectra give evidence of completely stretched chain segments which are located near the supramolecular clusters.The orientation behavior of elastomers has been studied extensively by means of a wide variety of different methods, e.g. FT-IR dichroism and strain birefringence. As a very powerful tool, 2 H-solid-state NMR was used to monitor dynamics and orientation on a molecular level simultaneously. Not only rigid (7 ) or liquid crystal (2 ) systems but also highly mobile materials such as elastomers (3 ) or even polymer melts (4 ) can be investigated. Mainly covalently endlinked PDMS networks were studied as models for 'ideal' networks. In order to understand the results of the NMR experiments different approaches have been developed based on short-range nematiclike orientational couplings (5), deformation behavior of single chains (6\ anisotropic junction fluctuations (7 ) or the effect of a screened potential (8 ). Turning towards more complex systems, the orientation behavior of statistically crosslinked polybutadienes and thermoplastic elastomers, such as poly(styrene-£-butadiene-ostyrene) block copolymers and segmented polyurethanes has also been investigated by means of 2 H-NMR (9 ).An unusual type of thermoreversible network was realized in flexible polydienes such as polybutadiene, which are attached by polar functional units (70 ).

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“…The fracture will be healed during the change of the temperature. Several multiple hydrogen bonds have been utilized to construct healable polymeric materials [26][27][28][29]. Ureido-pyrimidinone (UPy) reported by Meijer and coworkers [26] has been widely used in constructing supramolecular polymers, as a result of simple, efficient preparation methods and cheap starting materials.…”

Section: Healable Polymeric Materialsmentioning

confidence: 99%

Reversible cross-linking polymer-based self-healing materials

Wang

2015

Recent Advances in Smart Self-Healing Polymers and Composites

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New multiphase architecture from statistical copolymers by cooperative hydrogen bond formation

Cited by 65 publications

References 5 publications

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

Orientation Behavior of Thermoplastic Elastomers Studied by ²H-NMR Spectroscopy

Reversible cross-linking polymer-based self-healing materials

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New multiphase architecture from statistical copolymers by cooperative hydrogen bond formation

Cited by 65 publications

References 5 publications

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

Formation of cage-like particles by poly(amino acid)-based block copolymers in aqueous solution.

Orientation Behavior of Thermoplastic Elastomers Studied by 2H-NMR Spectroscopy

Reversible cross-linking polymer-based self-healing materials

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Product

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About

Orientation Behavior of Thermoplastic Elastomers Studied by ²H-NMR Spectroscopy