Combining stiffness and stretchiness There is usually a trade-off between making material stretchy, so that it can absorb energy on deformation, stiff, does not extend very much when stretched. Mussels have long been an inspiration for developing adhesives work wet. Filippidi et al. produced extensible polymeric containing catechol groups whose mechanical properties were augmented dry through the addition of iron ions (see Perspective by Winey). The lead to sacrificial metal coordination...

Phase separation and coacervate complex formation of poly(acrylic acid) (PAA) poly(allylamine hydrochloride) (PAH) were investigated as model pair oppositely charged, weak polyelectrolytes in aqueous solution. Both fully or partially neutralized PAA (sodium polyacrylate) PAH employed. Important factors affecting the complexation systematically varied including polyacid/polybase mixing ratio (10−90 wt %), ionic strength salt concentration (0−4700 mM), polymer (0.02−2.0 pH (5 7), temperature...

Phase separation of polyelectrolyte complexes (PECs) between the polyacid (sodium salt) and polybase (hydrochloride) poly(acrylic acid) (PAA) poly(allylamine) (PAH), respectively, has been investigated in aqueous solution. Chain length PAA was varied (25 < Pw 700) holding PAH constant at 765. The polyacid/polybase mixing ratio (10–90 wt %) ionic strength as salt concentration (0–3,000 mM) were systematically varied. Sample turbidity utilized an indicator PEC formation, complemented by...

Abstract Several acrylates and methacrylates were copolymerized with two 4‐aminoazobenzene methacrylic derivatives. The photochemical thermal cis‐trans isomerization about the azolink was investigated in bulk polymers. All copolymers show photochromic behaviour without fading; photostationary states upon irradiation UV‐light of appropriate wavelengths similar solution. follows simple first order kinetics rubbery specimens as Below glass transition temperature T g , can only be described by...

Numerous attempts have been made to translate mussel adhesion diverse synthetic platforms. However, the translation remains largely limited Dopa (3,4-dihydroxyphenylalanine) or catechol functionality, which continues raise concerns about Dopa's inherent susceptibility oxidation. Mussels evolved adaptations stabilize against For example, in foot protein 3 slow (mfp-3s, one of two electrophoretically distinct interfacial adhesive proteins plaques), high proportion hydrophobic amino acid...

Thanks to many promising properties, including biocompatibility and the ability experience large deformations, poly(ethylene glycol) diacrylate (PEGDA) hydrogels are excellent candidate materials for a wide range of applications. Interestingly, polymerization PEGDA leads network microstructure that is fundamentally different from "classic" polymeric gels. Specifically, comprise PEG chains interconnected by multifunctional densely grafted rod-like polyacrylates (PAs), which serve as...

Abstract The relation between the relaxation behaviour of photochromic aromatic azo benzenes and spiropyrans in a series amorphous polymers polymer properties has been investigated. distinctive differences rate thermal isomerization found below above T g also compared to solution can be explained by molecular matrix, i. e., overall chain segmental mobility, particular motions free volume effects. — temperature dependency photochromes described WLF‐equation, log = ‐ C 1 ( )/( 2 + ). numerical...

Spider silk is a protein material that exhibits extraordinary and nontrivial properties such as the ability to soften decrease its length by up ∼60% upon exposure high humidity. This process commonly called supercontraction result of transition from highly oriented glassy phase disoriented rubbery phase. In this work, we derive microscopically motivated energy-based model captures underlying mechanisms give rise supercontraction. We propose increase in relative humidity consequent wetting...

Spider silk is a protein material that exhibits extraordinary and nontrivial properties such as the ability to soften, decrease in length (i.e., supercontract), twist upon exposure high humidity. These behaviors stem from unique microstructure combination with transition glassy rubbery result of humidity-driven diffusion water. In this Letter we propose four scales govern mechanical response during transition. addition, develop model describes microstructural evolution spider thread explains...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and chain extension of bipyridine-terminated polyethers with copper(I) ionsClaus D. Eisenbach Ulrich S. SchubertCite this: Macromolecules 1993, 26, 7372–7374Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https://pubs.acs.org/doi/10.1021/ma00078a041https://doi.org/10.1021/ma00078a041research-articleACS PublicationsRequest reuse permissionsArticle...

Abstract Polyacrylamide hydrogels are widely used in biomedical applications due to their tunable mechanical properties and charge neutrality. Our recent tribological investigations of polyacrylamide gels have revealed pH-dependent friction behavior. To determine the origins this pH-responsiveness, we prepared with two different initiating chemistries: a reduction–oxidation (redox)-initiated system using ammonium persulfate (APS) N,N,N ′ N - tetramethylethylenediamine (TEMED) UV-initiated...

Abstract The neutron scattering from mixtures of deuterated and undeuterated poly(ethylene oxide), (D‐PEO, H‐PEO), in the small angle intermediate region has been measured melt. We found no indications a molecular segregation. value weight evaluated agreed with that obtained by other methods. For sample molar mass 120000 g/mol radius gyration 〈 r w 2 〉 1/2 was to be 13,6 nm, which corresponds characteristic ratio C = 6,9. form factor single chain can described Debye equation for random coil...

We investigated the morphology, topology, and mechanical characteristics of a loosely cross-linked epoxy network as function varying content catechol moieties capable forming reversible, ionic iron–catecholate cross-links. The primary structure was kept fixed by constant mole ratio difunctional poly(ethylene glycol), monofunctional diluent, diamine cross-linking agent in all samples. then systematically replaced monoepoxide diluent methyl glycidyl ether, which is incapable participating...

We determined the self part of intermediate scattering function in liquid polyethyleneoxide (PEO) and PEO–alkali iodide complexes by means neutron spin-echo spectroscopy molecular dynamics (MD) computer simulations. present first accurate quantitative results on segmental time range up to 1 ns wave-vector from a few nm−1 approximately 20 nm−1. investigate influence polymer chain length, salt concentration, cation type. find that data MD for pure PEO agree very well. A relatively small...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSegmented Polyurethane Elastomers with Liquid Crystalline Hard Segments. 1. Synthesis and Phase BehaviorWeiming Tang, Richard J. Farris, William MacKnight, Claus D. EisenbachCite this: Macromolecules 1994, 27, 10, 2814–2819Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue 1 1994https://pubs.acs.org/doi/10.1021/ma00088a023https://doi.org/10.1021/ma00088a023research-articleACS PublicationsRequest...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDeuteron NMR measurements of order and mobility in the hard segments a model polyurethaneJ. A. Kornfield, H. W. Spiess, Nefzger, Hayen, C. D. EisenbachCite this: Macromolecules 1991, 24, 17, 4787–4795Publication Date (Print):August 1, 1991Publication History Published online1 May 2002Published inissue 1 August 1991https://pubs.acs.org/doi/10.1021/ma00017a009https://doi.org/10.1021/ma00017a009research-articleACS PublicationsRequest reuse...

Abstract The structure of adsorption layers amphiphilic block and block‐like copolymers poly(isobornyl acrylate) poly(acrylic acid) on the surface hydrophilic titanium dioxide hydrophobic copper phthalocyanine (CuPc) pigments in an aqueous dispersion has been studied by electrokinetic sonic amplitude (ESA) method. electroacoustic behaviour polyelectrolyte copolymer‐coated particles could be described context polymer gel layer theory. around was found to much thinner for CuPc as compared TiO...