High-vacuum polymerization of R-(amino acid)-N-carboxyanhydrides (NCAs) affords polymers with controlled molecular weights and narrow polydispersities; however, a comprehensive study of the end-group composition of the resulting polypeptides has not yet been performed. This reveals crucial information, as the end-groups are indicative of both the polymerization mechanism (i.e., initiation event) and the termination pathways. To this end, poly(O-benzyl-L-tyrosine) initiated by 1,6-diaminohexane was synthesized and subsequently characterized by MALDI-TOF MS, NALDI-TOF MS, and 13 C NMR spectroscopy to ascertain the end-group structure. Polymers were prepared by both high-vacuum and glovebox techniques in DMF/THF. Preparation of poly(O-benzyl-L-tyrosine) by high-vacuum techniques yielded a polymer initiated exclusively by the normal amine mechanism, and termination by reaction with DMF was observed. In contrast, polymers prepared in the glovebox were initiated by the normal amine and activated monomer mechanisms, and several termination products are evident. To our knowledge, this is the first rigorous and comparative analysis of the end-group structure, and it demonstrates the advantage of highvacuum techniques for polymerization of NCAs for the preparation of well-defined polypeptides with endgroup fidelity.

Monolithic nanocarbon-based CO2 solid sorbents offer fast mass transport, easy handling, minor pressure drop, and cycle operation stability because of the interconnected three-dimensional network of pores that provides a unique porous structure. In this work, following a one-step water-based method, graphene-based monoliths were produced by a spontaneous reduction-induced self-assembly of graphene oxide nanoplatelets under mild conditions (45–90 °C). By varying the reaction temperature and amount of reducing agent (ascorbic acid, AsA), the engineering of the porous structure of the monoliths was performed and resulted in a portfolio of different monoliths with different capacities for CO2 adsorption. It was found that the monolith produced at the highest temperature and with the lowest AsA amount possessed the highest specific surface area and porosity as well as a high level of functionalization. As a result, this monolith presented an excellent CO2 capture performance of 2.1 mmol/g at T = 25 °C and P = 1 atm. This value is between the highest achieved in CO2 sorption in comparison to that of similar and nontreated materials. The selectivity of this monolith for CO2 capture over that for N2 at 25 °C and atmospheric pressure is 53, presenting a high viability for practical applications. The monolith was shown to lose capacity in cycle operations, probably because of the collapse of the smallest pores, which was solved by the addition of a small amount of polymer particles during the one-step synthesis of the monolithic structures. This modification provides for an excellent stability over five adsorption/desorption cycles.

Silencing RNA (siRNA) technologies emerge as a promising therapeutic tool for the treatment of multiple diseases. An ideal nanocarrier (NC) for siRNAs should be stable at physiological pH and release siRNAs in acidic endosomal pH, fulfilling siRNA delivery only inside cells. Here, we show a novel application of polyamine phosphate NCs (PANs) based on their capacity to load negatively charged nucleic acids and their pH stability. PANs are fabricated by complexation of phosphate anions from phosphate buffer solution (PB) with the amine groups of poly(allylamine) hydrochloride as carriers for siRNAs. PANs are stable in a narrow pH interval, from 7 to 9, and disassemble at pH's higher than 9 and lower than 6. siRNAs are encapsulated by complexation with poly(allylamine) hydrochloride before or after PAN formation. PANs with encapsulated siRNAs are stable in cell media. Once internalized in cells following endocytic pathways, PANs disassemble at the low endosomal pH and release the siRNAs into the cytoplasm. Confocal laser scanning microscopy (CLSM) images of Rhodamine Green labeled PANs (RG-PANs) with encapsulated Cy3-labeled siRNA in A549 cells show that siRNAs are released from the PANs. Colocalization experiments with labeled endosomes and either labeled siRNAs prove the translocation of siRNAs into the cytosol. As a proof of concept, it is shown that PANs with encapsulated green fluorescence protein (GFP) siRNAs silence GFP in A549 cells expressing this protein. Silencing efficacy was evaluated by flow cytometry, CLSM, and Western blot assays. These results open the way for the use of poly(allylamine) phosphate nanocarriers for the intracellular delivery of genetic materials.

Polymer composite materials with hierarchical porous structure have been advancing in many different application fields due to excellent physico-chemical properties. However, their synthesis continues to be a highly energy-demanding and environmentally unfriendly process. This work reports a unique water based synthesis of monolithic 3D reduced graphene oxide (rGO) composite structures reinforced with poly(methyl methacrylate) polymer nanoparticles functionalized with epoxy functional groups. The method is based on reduction-induced self-assembly process performed at mild conditions. The textural properties and the surface chemistry of the monoliths were varied by changing the reaction conditions and quantity of added polymer to the structure. Moreover, the incorporation of the polymer into the structures improves the solvent resistance of the composites due to the formation of crosslinks between the polymer and the rGO. The monolithic composites were evaluated for selective capture of CO2. A balance between the specific surface area and the level of functionalization was found to be critical for obtaining high CO2 capacity and CO2/N2 selectivity. The polymer quantity affects the textural properties, thus lowering its amount the specific surface area and the amount of functional groups are higher. This affects positively the capacity for CO2 capture, thus, the maximum achieved was in the range 3.56–3.85 mmol/g at 1 atm and 25 °C.

We report the observation of a cubic phase consistent with the double gyroid structure in strongly segregated diblock copolymers of PS‐b‐PDMS over a volume fraction (φPDMS) range of ∼0.39 to 0.45. The samples have respective molecular weights of 127 kg/mol and 73 kg/mol and degree of segregation Nχ equal to 187 and 106, respectively, at annealing temperature of 130 °C. It is important to highlight that two out of the total four samples investigated, exhibited hexagonally close packed cylindrical domains of PDMS and alternating lamellae at φPDMS = 0.39 and 0.45, respectively, indicating the possible narrow range of the DG morphology for the specific diblock copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2419–2427, 2009