Polymer Chemistry Blog

In this article, Vicent, Salmaso, Alexander and co-workers prepared a modular and effective controlled release system, based on polymers designed to respond to the pH-changes that occur in tissues affected by peculiar disease. The individual blocks were composed of (a) permanently hydrophilic chains with neutral functionality and (b) acrylate polymers with weakly basic side-chains. Variation in co-monomer content, molar mass and block ratios/compositions led to a range of pH-responses, manifested through reversible self-assembly into micelles and/or polymersomes. These transitions were tuned to achieve environmental responses in a pH range from 5–7. The ability of the systems assembled with these polymers to act as pH-responsive containers was shown by DNA encapsulation and release studies, and their potential for application as vehicle for drug delivery was proved by cell metabolic activity and cell uptake measurements.

Synthesis and characterization of variable conformation pH responsive block co-polymers for nucleic acid delivery and targeted cell entry by Teresa Matini, Nora Francini, Anna Battocchio, Sebastian G. Spain, Giuseppe Mantovani, Maria J. Vicent, Joaquin Sanchis, Elena Gallon, Francesca Mastrotto, Stefano Salmaso, Paolo Caliceti and Cameron Alexander Polym. Chem. 2014, 5, 1626-1636.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this publication, Themistou, Battaglia and Armes reported on the one-pot metal-free ring-opening polymerization (ROP)–reversible addition–fragmentation chain transfer (RAFT) synthesis of biocompatible linear and branched amphiphilic diblock copolymers based on a biodegradable aliphatic polyester (PLA) and methacrylic monomers (such as 2-(dimethylamino)ethyl methacrylate (DMA) or oligo(ethylene glycol) methacrylate (OEGMA)), using a novel hydroxyl-functionalized trithiocarbonate-based chain transfer agent. These amphiphilic diblock copolymers self-assembled in dilute aqueous solution, leading to various copolymer morphologies depending on the block compositions. Two novel disulfide-functionalized PLA-branched block copolymers were also synthesized using simultaneous ROP of LA and RAFT copolymerization of OEGMA or DMA with a disulfide-based dimethacrylate. The disulfide bonds were reductively cleaved using tributyl phosphine to generate reactive thiol groups. Thiol–ene chemistry was utilized for further derivatization with thiol-based biologically important molecules and heavy metals for tissue engineering or bioimaging applications, respectively.

Facile synthesis of thiol-functionalized amphiphilic polylactide–methacrylic diblock copolymers by Efrosyni Themistou, Giuseppe Battaglia and Steven P. Armes Polym. Chem. 2014, 5, 1405-1417.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this study, Voit, Appelhans and co-workers demonstrated the successful fabrication of biohybrid structures tailored by non-covalent interactions for potential biochemical applications. Using avidin-biotin conjugation as the deciding non-covalent interaction step, different nanometer-sized biohybrid structures can be established by using different molar interaction ratios between mono-, bi- and tetravalent biotinylated glycodendrimers and avidin.  The biotin ligand’s spacer length, its chemical structure and the degree of biotin functionalization were shown to be essential parameters in the formation of nanostructures with avidin having a controlled composition and size dimension up to 100 nm. Biohybrid structures with avidin as a central unit required monovalent glycodendrimers with PEG-linked biotin, while bi- and tetravalent glycodendrimers with short alkyl-linked biotin ligands were more efficient than their counterparts with longer PEG–biotin ligands in the fabrication of defined biohybrid structures (diameters up to 100 nm) with avidin as a bridging unit.  Not only does this study elucidate the formation of biohybrid structures between avidin and biotinylated glycodendrimers in the conjugation solution, but it also provides deeper insight into these supramolecular (bio)polymeric structures from a general point of view.

Biohybrid structures consisting of biotinylated glycodendrimers and proteins: influence of the biotin ligand’s number and chemical nature on the biotin–avidin conjugation by Franka Ennen, Susanne Boye, Albena Lederer, Mihaela Cernescu, Hartmut Komber, Bernhard Brutschy, Brigitte Voit and Dietmar Appelhans Polym. Chem. 2014, 5, 1323-1339.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this study, Poly, Lalevée, Matyjaszewski and co-workers reported on a new approach for the synthesis of dynamic covalent networks exhibiting self-healing properties under UV irradiation. The procedure combined ATRP and click chemistry as two versatile synthetic tools for the design of well-defined peripherally functionalized star-like oligomers followed by their covalent bonding with responsive alkoxyamine crosslinking agents. The incorporation of alkoxyamine linkages into the junctions between the stars enabled their subsequent cleavage under irradiation. Beyond self-healing materials, the concept developed in the present study might be of interest regarding aging issues of polymeric materials due to UV radiation.

Introduction of self-healing properties into covalent polymer networks via the photodissociation of alkoxyamine junctions by Siham Telitel, Yoshifumi Amamoto, Julien Poly, Fabrice Morlet-Savary, Olivier Soppera, Jacques Lalevée and Krzysztof Matyjaszewski Polym. Chem. 2014, 5, 921-930.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this study, van Hest and co-workers demonstrated that nanometer-sized polymersomes assembled from two dissimilar diblock copolymers can undergo shape changes, driven by strong lateral polymer/polymer segregation within the membrane. The two particular block copolymers consisted of identical hydrophobic fragments to stimulate co-assembly, while their hydrophilic segments were either neutrally or negatively charged. It was hypothesized that demixing of the two types of polymer amphiphiles within the bilayer was caused by the different hydrophilic polymer fractions exhibiting intrinsically different interfacial curvatures upon self-assembly. Given the potentially unlimited number of possible hybrid polymersome systems, the local polymer/polymer separation phenomenon could be easily exploited further in the construction of new polymersome morphologies, with potential applications in both nanoscience and biomedical fields.

Spontaneous shape changes in polymersomes via polymer/polymer segregation by Silvie A. Meeuwissen, Stéphanie M. C. Bruekers, Yingchao Chen, Darrin J. Pochan and Jan C. M. van Hest Polym. Chem. 2014, 5, 489-501.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this study, Crespy and co-workers developed an easy, low-cost and mild strategy to fabricate PPs in large quantities without using block copolymers. Polymerization-induced phase separation was found to be the reason for the formation of the PPs. The size of the patches could be easily tuned by controlling the monomer conversion or by changing the composition of the nanoparticles. The atomic force microscopy analysis revealed that the patches were sticky and embedded in a harder polymer matrix. Moreover, the patchy structure could be locked by cross-linking the sticky patches. Their approach could be extended to prepare large libraries of different PPs by choosing other polymer/monomer pairs and/or by post-functionalizing the patchy area.

Polymer patchy colloids with sticky patches by Yi Zhao, Rüdiger Berger, Katharina Landfester and Daniel Crespy Polym. Chem. 2014, 5, 365-371.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this study, Leibler and co-workers reported on the subtle influence of solvent on the organization of supramolecular polymers. They synthesized homotelechelic and heterotelechelic oligomers of poly(propylene oxide) (PPO) equipped with complementary hydrogen bonding functional ends, thymine (Thy) and diaminotriazine (DAT). In a solvent that dissociates Thy–DAT hydrogen bonds, such as DMSO, the viscosity was low for all functional telechelic oligomers. In non-dissociative solvents, the addition of functional oligomers increased the viscosity. For both the homotelechelic blends and the heterotelechelics, the viscosity in toluene was about two times higher than that in chloroform. Additionally, the Thy–DAT association constant was 22 times higher. Carbon relaxation times measured by NMR and viscosity variation for solutions of different concentrations suggest a distinct supramolecular organization in chloroform and toluene: linear and cyclic supramolecular chains in chloroform and small π-stacked objects with a PPO shell and a Thy, DAT core in toluene. One might expect that when the materials are obtained by solvent evaporation, the organization in the bulk is solvent dependent as this is often the case for ABC block copolymers.

Binding and supramolecular organization of homo- and heterotelechelic oligomers in solutions by Jessalyn Cortese, Corinne Soulié-Ziakovic and Ludwik Leibler Polym. Chem. 2014, 5, 116-125.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this study, Liu and co-workers reported a new strategy for the synthesis of polyaniline (PANI) nanostructures on a flexible G–carbon nanotube (G-CNT) composite paper substrate, which can be directly used as flexible electrodes possessing both electric double layer (EDL) capacitance and pseudocapacitance. The ternary hybrid paper exhibited a reversible capacity of up to 432 F g^-1 at a discharge rate of 0.5 A g^-1, which was much larger than that of bare G–CNT composite paper (172.4 F g^-1); and its cyclic performance was dramatically enhanced, sustaining greater than 96% of its original capacitance after 600 charge–discharge cycles. Besides, the good electrical conductivity of the G–CNT composite paper provided improved conductive pathways for charge transfer at the electrodes thus resulting in superior capacitance during charge–discharge processes. Therefore, the method reported here provides a simple and efficient approach to fabricating G–CNT–PANI ternary hybrid papers with designed hierarchical nanostructures, and may be easily extended to the design of next generation high performance flexible supercapacitors.

All-carbon composite paper as a flexible conducting substrate for the direct growth of polyaniline particles and its applications in supercapacitors by Chao Zhang, Weng Weei Tjiu and Tianxi Liu Polym. Chem. 2013, 4, 5785-5792.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In their paper, Lacroix-Desmazes and co-workers reported the synthesis of a CeO₂/poly(vinylidene chloride) (PVDC) hybrid latex carried out via the functionalization of CeO₂ nanoparticles by reversible addition-fragmentation chain transfer (RAFT) polymerization from a phosphonated macro-RAFT agent, with very efficient formation of hybrid structures (neither free ceria nanoparticles nor free latex particles). This hybrid latex, obtained by emulsion polymerization with a reasonably high solid content (25%), represents a good candidate for the elaboration of high performance coatings. Furthermore, the authors also considered the use of such hybrid latexes as templates for the preparation of functional organic or inorganic porous materials with CeO₂ nanoparticles (or other nanoparticles) evenly distributed in the porous matrix.

A CeO₂/PVDC hybrid latex mediated by a phosphonated macro-RAFT agent by Jérôme Warnant, Jérôme Garnier, Alex van Herk, Pierre-Emmanuel Dufils, Jérôme Vinas and Patrick Lacroix-Desmazes Polym. Chem. 2013, 4, 5656-5663.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this article, Zhang, Li and co-workers synthesized by Atom Transfer Radical Polymerization (ATRP) a highly water-soluble, multivalent and highly specific BODIPY-conjugated glycopolymer for direct tumor cell imaging, which showed good photostability. The cell viability of BODIPY-conjugated glycopolymers against HepG2 and NIH3T3 cells was more than 80%, indicating that the glycopolymers have low cytotoxicity to living cells. Moreover, simple incubation of living cells with a BODIPY-conjugated glycopolymer led to efficient internalization into HepG2 and clear visualization in cytoplasm, due to the high brightness of BODIPY and good specificity between HepG2 and galactose as compared to NIH3T3 cells. These results suggest that BODIPY-conjugated glycopolymers have potential use as fluorescent probes in live cell imaging.

Water-soluble BODIPY-conjugated glycopolymers as fluorescent probes for live cell imaging by Zhentan Lu, Lin Mei, Xinge Zhang, Yanan Wang, Yu Zhao and Chaoxing Li Polym. Chem. 2013, 4, 5743-5750.

Julien Nicolas is a guest web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.