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11.
M. Itxaso Calafel Elena Calahorra Pedro M. Remiro Milagros Cortazar 《Colloid and polymer science》2010,288(12-13):1281-1291
Thermoset/thermoplastic blends were prepared with epoxy–aromatic diamine mixtures and poly(L-lactide) (PLLA), as semicrystalline thermoplastic, in concentrations ranging from 4 to 25 wt.%. In some cases, poly(L,D-lactide) (PDLLA), an amorphous thermoplastic, was used instead for comparative purposes. Diglycidyl ether of bisphenol-A (DGEBA) was employed as epoxy resin and 4,4′-diaminodiphenylmethane (DDM) as curing agent. Phase behavior and morphology were studied during curing at 140 °C. Initially, all blends were homogeneous; however, the curing reaction of the epoxy resin caused a liquid–liquid phase separation. A co-continuous morphology was formed at the beginning of the phase separation in all the considered blend compositions. Blends evolved to a particle/matrix structure or to a phase-inverted structure depending on the initial blend composition. At 140 °C, crystallization only occurred in blends with 16 and 25 wt.% PLLA. This crystallization originates changes in the surface of the epoxy-rich droplets developed with the phase separation. 相似文献
12.
Hydrogel synthesis by aqueous Diels‐Alder reaction between furan modified methacrylate and polyetheramine‐based bismaleimides
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Clara García‐Astrain Itxaso Algar Alessandro Gandini Arantxa Eceiza María Ángeles Corcuera Nagore Gabilondo 《Journal of polymer science. Part A, Polymer chemistry》2015,53(5):699-708
A simple method for preparing cross‐linked hydrogels in an aqueous medium is investigated using Diels‐Alder (DA) “click” reaction, without employing a catalyst. A polymeric diene is first synthesized by the functionalization of poly(2‐aminoethyl methacrylate) hydrochloride with furfural. Suited bisdienophiles are prepared by modification of Jeffamine® ED of different molecular weights with maleic anhydride. Both precursors of the DA coupling are thoroughly characterized before their reactions. The ensuing hydrogels are analyzed in terms of their microstructure, swelling, and rheological behavior, as a function of the reaction conditions. The influence of the molecular weight of the cross‐linker and the furan‐to‐maleimide ratio on the final properties of the hydrogels were also investigated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 699–708 相似文献
13.
Palomo C Aizpurua JM Balentová E Azcune I Santos JI Jiménez-Barbero J Cañada J Miranda JI 《Organic letters》2008,10(11):2227-2230
Hybrid glycopeptide beta-lactam mimetics designed to bind lectins or carbohydrate recognition domains in selectins have been prepared according to a "shape-modulating linker" design. This approach was implemented using the azide-alkyne "click" cycloaddition reaction, and as shown by NMR/MD experiments, binding of the resulting mimetics to Ulex Europaeus Lectin-1 (UEL-1) occurred after a "bent-to-extended" conformational change around a partially rotatable triazolylmethylene moiety. 相似文献
14.
Tarbe M Azcune I Balentová E Miles JJ Edwards EE Miles KM Do P Baker BM Sewell AK Aizpurua JM Douat-Casassus C Quideau S 《Organic & biomolecular chemistry》2010,8(23):5345-5353
β-Lactam peptides were envisioned as conformational constraints in antigenic peptides (APs). Three different β-lactam tripeptides of varying flexibility were prepared in solution and incorporated in place of the central part of the altered melanoma associated antigenic peptide Leu(27)-Melan-A(26-35) using solid phase synthesis techniques. Upon TFA cleavage from the solid support, an unexpected opening of the β-lactam ring occurred with conservation of the amide bond. After adaptation of the solid phase synthesis strategy, β-lactam peptides were successfully obtained and both opened and closed forms were evaluated for their capacity to bind to the antigen-presenting class-I MHC HLA-A2 protein system. None of the closed β-lactam peptides bound to HLA-A2, but their opened variants were shown to be moderate to good HLA-A2 ligands, one of them being even capable of stimulating a Melan-A-specific T cell line. 相似文献
15.
Gutierrez J Tercjak A Algar I Retegi A Mondragon I 《Journal of colloid and interface science》2012,375(1):88-93
In this article, we report the first micellization study of amphiphilic copolymers composed of bacterial medium chain length poly(3-hydroxyalkanoates) (mcl-PHAs). A series of diblock copolymers based on fixed poly(ethylene glycol) (PEG) block (5000 g mol(-1)) and a varying poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate) (PHOHHx) segment (1500-7700 g mol(-1)) have been synthesized using "click" chemistry. These copolymers self-assembled to form micelles in aqueous media. The influence of PHOHHx block molar mass on the hydrodynamic size and on the critical micelle concentration (CMC) has been studied using dynamic light scattering and fluorescence spectroscopy, respectively. With increasing PHOHHx length, narrowly distributed micelles with diameters ranging from 44 to 90 nm were obtained, with extremely low CMC (up to 0.85 mg/L). Cryogenic transmission electron microscopy (Cryo-TEM) showed that micelles took on a spherical shape and exhibited narrow polydispersity. Finally, the colloidal stability of the micelles against physiological NaCl concentration has been demonstrated, suggesting they are promising candidates for drug delivery applications. 相似文献
16.
Guillermina Burillo Miriam F. Beristain Ernesto Sanchez Takeshi Ogawa 《Polymer Degradation and Stability》2013
The effects of four aromatic diacetylenes on the gamma-irradiation-induced degradation of a commercial polyurethane were studied. Addition of 1 wt% of diphenylbutadiyne, which is homogeneously distributed in the polymer, effectively suppressed the polymer chain degradation. The dose required to decrease tensile strength by 50% was found to be 582 kGy for the polyurethane with 1 wt% of diphenylbutadiyne, while a dose of only 310 kGy for the polyurethane itself. The Young's modulus of the polyurethane alone decreased with dose; meanwhile the films with diphenylbutadiyne did not change. The films with p,p′-dinitrodiphenylbutadiyne behaved differently from others due to their inhomogeneous composition. The amide substituted diacetylenes also showed protecting effect, but in less extent due to the steric effect. 相似文献
17.
Susana Hernández Hirohiko Miura Miriam F. Beristain Takeshi Ogawa Toshiyuki Watanabe Seizo Miyata 《Macromolecular Symposia》2003,192(1):123-134
In order to obtain polymers having high second order nonlinear optical (NLO) response, various novel polymers that contain polar dye molecules in side chains and diacetylenic groups in the main chains were synthesized, and their second order NLO properties were studied. Some of these polymers consisting of para-benzoate and para-cinnamate main chains, showed extremely high NLO coefficients, d33 of 200 - 350 pm/V, and the corresponding meta polymers showed much inferior NLO coefficients. The polymers having aliphatic main chains had very little NLO response probably because of their low glass transition temperatures and flexibility of main chains. The high SHG responses of these polymers are attributed to their facile orientation of both chromophores and main chains. In the case of para-polymers, the main chain orientation of alkoxybenzoate and cinnamate along the chromophore is thought to be a reason for their high NLO coefficients. 相似文献