The contribution of supramolecular chemistry to polymer science opens new perspectives for the design of polymer materials exhibiting valuable properties and easier processability due to the dynamic ...nature of non‐covalent interactions. Hydrogen bonding polymers can be used as supramolecular units for yielding larger assemblies that possess attractive features, arising from the combination of polymer properties and the responsiveness of hydrogen bonds. The post‐polymerization modification of reactive end‐groups is the most common procedure for generating such polymers. Examples of polymerizations mediated by hydrogen bonding‐functionalized precursors have also recently been reported. This contribution reviews the current synthetic routes toward hydrogen bonding sticker chain‐end functionalized polymers.
This Review summarizes recent advances in the design of hydrogen bonding chain‐end functionalized polymers through post‐polymerization functionalization or introduction of binding motifs in the course of the polymerization.
Immediate breast reconstruction (IBR) techniques are rapidly evolving. We compared the results from a single-center implant IBR cohort between subpectoral and prepectoral implants with and without a ...mesh.
We analyzed all complications and grade 2-3 complications, the implant loss rate, the surgery time, the length of stay (LOS), patient satisfaction, the interval time to adjuvant therapy and cost, with a comparison between subpectoral and prepectoral implant IBR.
Subpectoral implant IBR was carried out in 529 mastectomies (62.0%) and prepectoral in 324, with a significant increase in prepectoral placement in recent years. Mesh was used in 176 prepectoral placements (54.3%). Any grade of complication was reported in 147 mastectomies (17.2%), with a significantly higher rate for prepectoral implant IBR (
= 0.036). Regression analysis showed that prepectoral implant was not significantly associated with any grade of complication or with grade 2-3 complications. Prepectoral implant IBR was associated with a significantly shorter operative time and lower LOS. Grade 2-3 complications were significantly associated with lower satisfaction. Higher costs were significantly associated with the subpectoral placement and mesh. A complication rate predictive score identified five groups with a significant increase in grade 2-3 complications.
Prepectoral-M-IBR increased over time with no difference in complication rates compared to subpectoral-M-IBR. Prepectoral implant placement can be considered a safe technique.
We report an original strategy toward the straightforward preparation of precisely defined telechelic H-bonding polymers and the generation of supramolecular block copolymers thereof. Making use of ...an α,ω-functionalized symmetrical trithiocarbonate bearing thymine groups at both chain ends, a series of heterocomplementary H-bonding polymers were effortlessly generated by RAFT polymerization in a one step process. The resulting telechelic macromolecules selectively interacted with heterocomplementary α-DAP-functionalized chains to afford supramolecular block copolymers in solution and in bulk. These self-assemblies were evidenced by 1H NMR and rheological measurements. As a consequence of these associations, whereas non functional homopolymer blends tended to microphase separate as observed by AFM analysis, H-bonding homopolymer blends exhibited homogeneous microstructures in accord with the formation of supramolecular block copolymers promoting the stabilization of the interface between the polymers.
Supramolecular miktoarm stars (AB2 type) composed of poly (methyl methacrylate)-polystyrene2 (PMMA-PS2), poly(isoprene)-polystyrene2 (PI-PS2), and poly(vinyl acetate)-polystyrene2 (PVAc-PS2) were ...successfully synthesized by assembling reversible addition−fragmentation chain transfer (RAFT)-polymerized chains bearing hydrogen-bonding heterocomplementary associating units. To this end, thymine and diaminopyridine-functionalized chain transfer agents were designed to efficiently mediate the polymerization of vinyl acetate, methyl methacrylate, isoprene, and styrene. The selective associations of the resulting hydrogen-bonding macromolecular building blocks PVAc/PS, PI/PS, and PMMA/PS were demonstrated by 1H NMR in CDCl3 solutions. Miktoarm stars formation in the bulk was also confirmed by transmission electronic microscopy.
We describe an approach to ordered nanoporous poly(lactide) that relies on self-assembly of poly(butadiene)–poly(lactide) (PB–PLA) diblock copolymers followed by selective degradation of PB using ...olefin metathesis. The block copolymers were obtained by a combination of anionic and ring-opening transesterification polymerizations. The molar mass of each block was tailored to target materials with either a lamellar or cylindrical microphase-separated morphology. Orientation of these nanoscale domains was induced in thin films and monolithic samples through solvent annealing and mechanical deformation, respectively. Selective degradation of PB was achieved by immersing the samples in a solution of Grubbs first-generation catalyst in cyclohexane, a nonsolvent for PLA. Successful elimination of PB was confirmed by size-exclusion chromatography and 1H NMR spectroscopy. Direct imaging of the resulting nanoporous PLA was obtained by scanning electron microscopy.
Azido β-cyclodextrins were attached to propiolate-functionalized polydimethylsiloxanes by metal-free click chemistry. The obtained telechelic copolymers spontaneously produced elastomeric gums. ...Demixing and supramolecular associations are the driving forces for the construction of these strongly associated (but reversible) physical networks.
A new facile fabrication approach to generate polymeric nanostructures is described. Block copolymers containing immiscible segments can self-assemble to generate ordered nanostructures, such as ...cylinders of one block in a matrix of the other in the bulk, which can then be sectioned on the nanoscale using a microtome (nanoskiving). Dispersing these sections in a selective solvent for the matrix block results in nanocylinders. In one example, we utilized a poly(N,N-dimethylacrylamide)-block-poly(styrene) (PDMA–PS) copolymer containing 36% by volume of PS. This composition was selected as it self-assembles into cylinders of PS in a matrix of PDMA. Following a previously described procedure, the cylinders were aligned using a channel die. The aligned samples were subsequently sectioned using a microtome containing a diamond knife and dispersed in water, a selective solvent for the PDMA matrix, affording PS nanocylinders with a PDMA corona. This technique allows tuning of nanocylinders without the requirement of specialty fabrication equipment.
Au cours de la dernière décennie, quelques (rares) exemples de copolymères à blocs présentant des liens supramoléculaires entre les blocs constitutifs ont été décrits. En raison du caractère ...réversible de l’association des blocs macromoléculaires, de tels polymères sont d’un grand intérêt pour le développement de matériaux nanostructurés, ayant des propriétés auto-cicatrisantes ou à processabilité améliorée. L’objectif principal de cette thèse est d’élaborer de nouvelles architectures supramoléculaires, en combinant la polymérisation RAFT et l’association spécifique par liaisons H des groupements thymine et diaminopyridine. La stratégie employée a consisté dans un premier temps en la synthèse d’agents de transfert et d’un amorceur radicalaire fonctionnalisés par des unités complémentaires thymine et diaminopyridine. Ces précurseurs ont permis de générer, par polymérisation RAFT, des polymères α- ou α,ω-fonctionnalisés de manière quantitative par ces motifs à liaisons H. L’auto-assemblage des blocs polymères ainsi obtenus a été mis en évidence par RMN 1H, AFM et par des mesures rhéologiques. Cette démarche a été adaptée dans un second temps à l’élaboration de copolymères greffés supramoléculaires hydrophiles, basés sur le complexe d’inclusion β-cyclodextrine/adamantane.
Over the past decade, some (rare) examples of block copolymers with supramolecular links between the building blocks have been described. Because the association between macromolecular blocks is a reversible process, such polymers are of great interest in the field of nanostructured materials, self-healing materials, or processing aid. The main goal of this work is to develop new supramolecular architectures, by a combination of RAFT polymerization and H-bonding. In a first step, several chain transfer agents and a radical initiator possessing complementary thymine or diaminopyridine H-bonding moeties were synthesized. These precursors were used to generate a panel of polymers α- or α,ω-functionalized with these H-bonding stickers in a quantitative manner. The self-assembly of the resulting polymer blocks was highlighted by 1H NMR, AFM and rheological measurements. This approach was subsequently adapted to the development of hydrophilic supramolecular comb-shaped polymers, based on the β-cyclodextrin/adamantane host/guest complexation.
Au cours de la dernière décennie, quelques (rares) exemples de copolymères à blocs présentant des liens supramoléculaires entre les blocs constitutifs ont été décrits. En raison du caractère ...réversible de l'association des blocs macromoléculaires, de tels polymères sont d'un grand intérêt pour le développement de matériaux nanostructurés, ayant des propriétés auto-cicatrisantes ou à processabilité améliorée. L'objectif principal de cette thèse est d'élaborer de nouvelles architectures supramoléculaires, en combinant la polymérisation RAFT et l'association spécifique par liaisons H des groupements thymine et diaminopyridine. La stratégie employée a consisté dans un premier temps en la synthèse d'agents de transfert et d'un amorceur radicalaire fonctionnalisés par des unités complémentaires thymine et diaminopyridine. Ces précurseurs ont permis de générer, par polymérisation RAFT, des polymères α- ou α,ω-fonctionnalisés de manière quantitative par ces motifs à liaisons H. L'auto-assemblage des blocs polymères ainsi obtenus a été mis en évidence par RMN 1H, AFM et par des mesures rhéologiques. Cette démarche a été adaptée dans un second temps à l'élaboration de copolymères greffés supramoléculaires hydrophiles, basés sur le complexe d'inclusion β-cyclodextrine/adamantane.
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