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Thermoresponsive and active functional fiber mats were prepared from random copolymer of poly(pentafluorophenyl acrylate-co-N-isopropylacrylamide) (P(PFPA-co-NIPAM)), which was synthesized by a controlled radical polymerization process based on reversible addition-fragmentation chain transfer (RAFT). As reactive sites, pentafluorophenyl ester (PFP) groups were incorporated in the copolymer to allow for a multiple post-polymerization modification. UV-cross-linkable moieties were first introduced by partially reacting PFP groups in the copolymer with ortho-nitrobenzyl (ONB)-protected diamine. Electrospinning the resulting ONB-containing P(PFPA-co-NIPAM), followed by UV-induced cross-linking, yielded stable cross-linked thermoresponsive PNIPAM-based fiber mats. The remaining PFP active groups on the surface of copolymer fiber mats allowed for further conjugation with an H-Gly-Arg-Gly-Asp-Ser-OH (GRGDS) peptide, a well-known cell adhesive peptide sequence that was selected as a model in order to promote cell growth. At 37 °C, fibroblast cells were found to attach, spread, and proliferate well on the GRGDS-immobilized cross-linked (CL) fiber mat, as opposed to those on the GRGDS-immobilized un-cross-linked (UCL) fiber mat. By decreasing the temperature down to 20 °C, i.e. below the lower critical solution temperature (LCST) of thermoresponsive PNIPAM, cultured cells could easily be released from both GRGDS-immobilized CL and UCL fiber mats, whereas no cells were detached from tissue culture polystyrene (TCPS). These results suggest that the thermosensitive and active functional fiber mat obtained in this research represent an attractive and versatile platform for cultured cell recovery, which is beneficial for tissue engineering applications.

Over the years, nitrogen‐rich functional groups like tetrazole and its derivatives have received increasing interest in the chemistry of small molecules. There is a continuously growing interest in polymers decorated with nitrogen for potential biomedical applications because of their broad range of biological properties, such as being antibacterial, anticarcinogenic, and anti‐inflammatory. On this premise, a new synthesis route is reported for nitrogen‐decorated polymers via the combination of Ugi‐azide four‐multicomponent reaction (UA‐4MCR) and thiol‐ene polymerization. Accordingly, α,ω‐diene monomers decorated with (bis‐)1,5‐disubstituted‐1H‐tetrazoles (bis‐1,5‐DS‐Ts) are synthesized by using the UA‐4MCR. Subsequently, the light‐induced thiol‐ene polymerization facilitates the efficient synthesis of novel tetrazole‐decorated polymers with apparent number average molecular mass (Mn) up to 62 000 g mol−1, which are characterized for their chemical, thermal, and optical properties. The comprehensive characterization of the synthesized polymers is paving the way toward a wealth of opportunities, ranging from biomaterials to energy storage−relevant materials. [ABSTRACT FROM AUTHOR]

Herein, a new method to synthesise epoxide-based sequence-controlled polymers via anionic ring-opening monomer addition, a form of anionic ring-opening polymerisation, is presented. This technique allows in combination with post-polymerisation modification (PPM) reactions for the successful preparation of modified mPEG-b-oligo(allyl glycidyl ether) featuring the incorporation of one repeating unit on average at a time. Due to the possible introduction of a vast variety of molecules to the polymeric system via PPM reactions, a multitude of advanced functional polymeric materials can be generated. This, in combination with the chain extension reactions, allows for the synthesis of well-controlled and programmable architectures with particular properties. The structure of the sequence-controlled polymer was confirmed via ¹H NMR spectroscopy, size exclusion chromatography, attenuated total reflection Fourier-transform infrared spectroscopy, and differential scanning calorimetry [ABSTRACT FROM AUTHOR]

Researchers have dedicated their efforts for the creation of a wide choice of complex and precise macromolecular architectures over the past 100 years. Among them, cyclic polymers benefit from their absence of terminal chains and from their singular topology to minimize their hydrodynamic volume in solution, increase their chemical stability, limit their number of possible conformations as well as a reduce their propensity to crystallize or to form entanglements in comparison to their acyclic counterparts. While monocyclic structures have already been widely investigated and reviewed, reports on more complex polycyclic structures are rare. In this regard, cage‐shaped polymers—consisting of at least three polymer chains covalently interconnected through strictly two junction points—have received little attention over the past two decades. Although their synthesis is a worthy challenge, only a few synthetic methodologies of polymer cages were successfully developed so far. Thus, this review intends to highlight the key concepts of the conception of cage‐shaped polymers in addition to propose an actual and exhaustive state‐of‐art concept of their synthesis to rationally promote the next‐generation synthesis strategies. [ABSTRACT FROM AUTHOR]

Herein the decarboxylation of poly[N‐(acryloyloxy)phthalimide] (PAP) for the synthesis of functionalized polymers is reported. PAP homopolymer and block copolymers are used as precursor polymers for the straightforward functionalization via decarboxylation and subsequent Michael‐type addition or nitroxide radical coupling (NRC). [ABSTRACT FROM AUTHOR]

The polymerization of 2,3,4,5,6‐pentafluorobenzyl 2‐diazoacetate is conducted at ambient temperature and catalyzed by [(l‐prolinate)RhI(1,5‐dimethyl‐1,5‐cyclooctadiene)] or [(l‐prolinate)RhI(1,5‐cyclooctadiene)] yielding C1 polymers with molecular weights of 3000–4000 g mol−1 and dispersity between 1.1 and 1.3. Incorporation of the pentafluorobenzyl group into the C1 polymer results in a different solubility when compare to its C2 analog poly(2,3,4,5,6‐pentafluorobenzyl methacrylate). Efficient postmodifications via para‐fluoro‐thiol reaction with different thiols are conducted with this C1 polymethylene. [ABSTRACT FROM AUTHOR]

Azobenzene‐containing liquid crystal polymers (azo‐LCPs) with reactive groups attract much attention due to the combined properties of liquid crystallinity, photoresponsivity and reactivity, which make them promising in designing intelligent photo‐driven soft actuators. Herein, a post‐polymerization modification strategy is used to prepare a series of reactive azo‐LCPs using the trans‐esterification reaction of poly(pentafluorophenyl acrylate) with functional alcohols. These reactive azo‐LCPs show good capabilities in fabricating fibers via a simple thermal‐drawing method and subsequent crosslinking reaction with diamine under mild conditions. Furthermore, the prepared fibers exhibit reversible deformation behaviors under the alternate irradiation of UV and visible light (365/530 nm). This facile synthetic strategy is expected to open up new possibilities for fabricating photo‐driven actuators. [ABSTRACT FROM AUTHOR]

Living cationic polymerization is known for a good control over chain growth yielding polymers with well‐defined molar mass distributions and low dispersities. However, the practical challenges involved in the synthesis of poly(vinyl ether)s limited suitable post‐polymerization modifications (PPM) via chemoselective click reactions. Herein the successful controlled cationic polymerization of vinyl ethers bearing pendant CC double and C≡C triple bonds using a single‐component initiation under ambient conditions is reported. Furthermore, the PPM via thiol‐ene/‐yne and copper(I)‐catalyzedalkyne‐azide cycloaddition reaction of the obtained polymers is successfully realized laying the foundation for the synthesis of unprecedented functional poly(vinyl ether)s. [ABSTRACT FROM AUTHOR]

The preparation of polymers containing sulfur–nitrogen bond derivatives, particularly 2,2,6,6‐tetramethylpiperidine‐1‐sulfanyl (TEMPS) dimers (i.e., BiTEMPS), has been limited to free‐radical or conventional step‐growth polymerization as result of the inherent thermal lability of the BiTEMPS unit. Accordingly, a novel poly(diaminodisulfide) possessing the BiTEMPS functional group is synthesized via acyclic diene metathesis (ADMET) polymerization at 65–75 °C within 3 h with precise control over the primary polymer structure. Polymer is isolated with an Mn of 20 400 g mol−1 and Ð of 1.9. Importantly, detailed nuclear magnetic resonance (NMR), size exclusion chromatography, attenuated total reflectance Fourier transform infrared (ATR‐IR) in addition to elemental analysis studies of the BiTEMPS polymer confirm the successful polymerization, and show that the BiTEMPS unit remains intact during the polymerization process. Furthermore, the previously unexplored UV‐responsiveness of the BiTEMPS decorated polymer backbone is investigated for the very first time. [ABSTRACT FROM AUTHOR]

Polymers with sulfur–nitrogen bonds have been underestimated for a long time, although the intrinsic characteristics of these polymers offer a myriad of superior properties (e.g., degradation, flame retardancy, film‐forming ability, good solubility in polar solvents, and high refractivity with small chromatic dispersions, among other things) compared to their carbon analogues. The remarkable characteristics of these polymers result from the unique chemical properties of the sulfur–nitrogen bond (e.g., its polar character and the multiple valence states of sulfur), and thus open excellent perspectives for the development of innovative (bio)materials. Accordingly, this review describes the most common chemical approaches toward the efficient synthesis of these ubiquitous polymers possessing diverse sulfur–nitrogen bonds, and furthermore highlights their applications in multiple fields, ranging from biomedicine to energy storage, with the aim of providing an informative perspective on challenges facing the synthesis of sulfur–nitrogen polymers with desirable properties. [ABSTRACT FROM AUTHOR]

Synthesis of functional polyacrylates by 4-dimethylaminopyridine (DMAP) catalyzed trans-esterification of poly(pentafluorophenyl acrylate) (polyPFPA) is reported. High fidelity and versatility of this strategy was exemplified by near quantitative conversion with diverse functional alcohols (primary, secondary as well as phenolic) featuring reactive groups like alkene, alkyne or acrylate, enabling further sequential functionalization using click chemistry. Co-integrating an equimolar mixture of allyl and propargyl alcohol produced an orthogonally clickable copolymer by thiol-ene and 1,3-cycloaddition reaction. Base catalyzed ester exchange allowed installation of acid labile Boc-l-serine to create amino acid pendent polymer keeping both NH2- and COOH-group free, thereby providing a facile route toward zwitterionic polymers. Reaction with 2-dimethylaminoethanol conferred dual pH and CO2 responsive polymers from the same reactive precursor. The synthetic strategy was further extended to attach alcohols obtained from natural resources such as geraniol, l-lactic acid or sesamol to engineer new renewable polymers. Even a graft copolymer with very high (93%) grafting density could be achieved utilizing PEG350-OH. The trans-esterification was found to be highly selective for primary alcohols over secondary alcohols and also to the activated PFP-ester over a normal ester such as poly(methyl acrylate). Using such selectivity, fluorescently tagged polymer could be synthesized by replacing only the PFP-ester of a poly(methyl acrylate-co-PFPA) with 1-pyrenemethanol. Further, PFPA was polymerized with 2.0 mol % diacrylate to produce a cross-linked gel network. The PFP-ester groups of the cross-linked gel could be quantitatively replaced with Boc-l-serine, which upon deprotection of the Boc group resulted in a novel zwitterionic hydrogel exhibiting pH-dependent swelling properties. Time-dependent FTIR experiment suggested fast kinetics of the reaction, making this synthetic route practically applicable for postpolymerization modification. Mechanistic investigation exposed involvement of both DMAP and the nucleophilic solvent N,N-dimethylformamide (DMF) in catalyzing the reaction. This also explains the reason as to why near quantitative conversion was achieved in DMF and not in the non-nucleophilic solvent 1,4-dioxane. [ABSTRACT FROM AUTHOR]

Novel thermosensitive nanocomposite (NC) hydrogels consisting of organic/inorganic networks are prepared via in situ free radical polymerization of 2-(2-methoxyethoxy) ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methacrylate (OEGMA) in the presence of inorganic cross-linker clay in aqueous solution. The obtained clay/P(MEO2MA -co-OEGMA) hydrogels exhibit double volume phase transition temperatures, an upper critical solution temperature (UCST), and a lower critical solution temperature (LCST), which can be controlled between 5 and 85 °C by varying the fraction of OEGMA units and the weight percentage of cross-linker clay. These new types of NC hydrogels with excellent reversible thermosensitivity are promising for temperature-sensitive applications such as smart optical switches. [ABSTRACT FROM AUTHOR]

A Mitsunobu reaction of trifluoroacetamide (TFA amide) and alcohols is used in a post-polymerization modification process. The reaction is conducted on polystyrene (PSt) bearing 20 mol% TFA amide groups with 4-methyl benzyl alcohol in the presence of a N,N,N′,N′-tetramethylazodicarboxamide and tributylphosphine as mediators. The Mitsunobu reaction on polymer proceeds efficiently, as confirmed by the obvious precipitation generation during the reaction and the conversion of TFA amide moiety reached 88.6% confirmed by 19F NMR measurement, yielding PSt bearing tertiary TFA amide moieties. The obtained polymers featuring tertiary TFA amide moieties are deprotected in the presence of tetrabutylammonium hydroxide as a base to afford corresponding polymers featuring functionalized polyamine scaffolds with 92.5% conversion. In addition, the precise structural assignment is proven by synthesis and analysis of the model monomeric compounds and the respective model polymers. [ABSTRACT FROM AUTHOR]

Ferrocene is incorporated into a poly(acetylene) derivative via the postpolymerization amidation of a polymer precursor bearing pentafluorophenyl ester-leaving groups with aminoferrocene. While the neutral polymer exhibits a strong absorbance at 553 nm due to its conjugated backbone, oxidation of the ferrocene moieties with silver tetrafluoroborate causes the material to absorb in the near-IR ( λmax ≈1215 nm). Subsequent reduction of the oxidized polymer with decamethylferrocene restores the initial absorbance profile, demonstrating that the material features switchable visible/near-IR absorption characteristics. [ABSTRACT FROM AUTHOR]

Substituted polyphenylacetylenes featuring reactive pentafluorophenyl (PFP) ester moieties are synthesized. Parts of the reactive PFP groups are then converted with a mono ortho-nitrobenzyl-protected diamine in variable ratios. Thin films are prepared from these copolymers and irradiated with UV light ( λ = 365 nm), resulting in crosslinking of the irradiated areas and hence enabling a photopatterning. We found that during the photocrosslinking process, the excess of PFP ester moieties is stable and remained intact, enabling a subsequent post-polymerization modification step with amines. Noteworthy, this subsequent modification with amines results in a dramatically shift in the UV-vis absorption spectra, rendering these patterned conjugated polymer films ideal candidates for optical sensors. [ABSTRACT FROM AUTHOR]

With a span as long as the history of polymer science itself, post-polymerization modification represents a versatile platform for the preparation of diversely functionalized polymers from a single precursor. Starting with the initial efforts by Staudinger in the 1920s, many of the early developments in modern polymer science can be attributed to the utilization of post-polymerization modification reactions. The scope of post-polymerization modification has greatly expanded since the 1990s due to the development of functional group tolerant controlled/living polymerization techniques combined with the (re)discovery of highly efficient coupling chemistries that allow quantitative, chemoselective, and orthogonal functionalization of reactive polymer precursors. After some basic mechanistic considerations, this Highlight will provide an overview of the development and evolution of eight main classes of post-polymerization modification reactions. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 [ABSTRACT FROM AUTHOR]

RAFT polymerization of 4-acryloxyphenyldimethylsulfoniumtriflate (SR-AEM) using pentafluorophenyl-(4-phenylthiocarbonylthio-4-cyanovalerate)as the chain transfer agent and AIBN as a radical source in acetonitrileat 90 °C yielded poly(4-acryloxyphenyldimethylsulfonium triflate)(poly(SR-AEM))s in high yields with well-controlled molecular weightsand polydispersity indices. The reactive polymer poly(SR-AEM) wasconverted using an excess amount of amines, e.g., isopropylamine yieldingpredominantly poly(N-isopropylacrylamide) with defectsof poly(4-acryloxyphenyl methylsulfide) in a minor ration of lessthan 16%. Furthermore, poly(SR-AEM) could be converted by thermo-triggeredrelease of methyl group at dimethylsulfonium ion group to afford poly(4-acryloxyphenylmethylsulfide) (poly(APM)) as proved by 1H NMR measurements,which did not react with amines anymore. To the best of our knowledge,this represents the first temperature-induced “on–offswitching” of the reactivity of an activated ester by using4-dimethylsulfonim phenol as the stimuli-responsive leaving group. [ABSTRACT FROM AUTHOR]

Two photoreactive pyridinium ylide containing monomers, {[2-(metacryloyloxy)ethoxy]carbonyl}(pyridinium-1-yl)azanide (M1) and pyridinium-1-yl-(4-vinylbenzoyl)azanide (M2), were synthesized. Both monomers were polymerized under controlled radical polymerization conditions, i.e. reversible addition--fragmentation chain transfer polymerization (M1 and M2) and nitroxide-mediated polymerization (M2). Further block copolymers PMMA-b-PM1 and PS-b-PM2 were successfully synthesized and their molecular weight, Mn, and block ratio could be determined by ¹H NMR analysis, thereby opening the synthetic possibilities of photoreactive ylides in block copolymer syntheses. [ABSTRACT FROM AUTHOR]

Abstract: Nine active ester monomers based on 4-vinylbenzoic acid have been synthesized. Under free radical polymerization conditions these monomers could successfully be polymerized yielding reactive polymers with molecular weights of around M n =20.000–50.000g/mol and molecular weight distributions M w/M n of around or below 2 in good yields. Polymer analogous reactions with amines have been investigated by time-resolved FT-IR spectroscopy and it was found that especially poly(pentafluorophenyl 4-vinylbenzoate) featured a significant reactivity, such that polymer analogous reactions proceeded quantitatively with amines within less than 5min at 0°C. [Copyright &y& Elsevier]

Abstract: Acetone oxime acrylate has been synthesized as a new active ester monomer. Free radical polymerization yielded a reactive polymer soluble in various organic solvents, such as chloroform, dioxane, DMSO, acetone, methanol, dichloromethane, DMF, and ethanol. Controlled radical polymerization of acetone oxime acrylate was successfully conducted using the RAFT, NMP and Iniferter method. Partly polymer analogous reaction with N-isopropylamine resulted in the reactive copolymer poly(N-isopropylacrylamide-co-acetone oxime acrylate), which featured a lower critical solution temperature (LCST) of 61°C in water. Further, the reactivity of the copolymer was exemplary proven by complete reaction with ammonia yielding poly(N-isopropylacrylamide-co-acrylamide), which does not possess a LCST. [Copyright &y& Elsevier]

The polymerization‐induced self‐assembly (PISA) of amphiphilic diblock copolymer nano‐objects, which are synthesized via reversible addition‐fragmentation chain‐transfer (RAFT) aqueous polymerization, is discussed. First, the effectiveness of the (S)‐2‐(ethyl propionate)‐(O‐ethyl xanthate) as a RAFT chain transfer agent for the polymerization of N,N‐dimethylacrylamide (DMAm) yielding a water‐soluble macro RAFT agent is investigated. In a second step, poly(DMAm) macro‐CTA is chain‐extended with acrylate monomers in water inducing a PISA process. Besides the use of pentafluorophenyl acrylate (PFPA) as core‐forming block, the thermo‐responsive nature of N‐isopropylacrylamide (NIPAm) and the reactive character of pentafluorophenyl acrylate (PFPA) for a subsequent post‐modification is exploited. Monomer conversion and reaction kinetics are determined via nuclear magnetic resonance spectroscopy, while gel permeation chromatography is used to evaluate the molecular weight distribution of the polymers. The obtained spherical nanostructures are analyzed via dynamic light scattering, scanning electron microscopy, transmission electron microscopy and atomic force microscopy. Diblock copolymer micelles with poly(NIPAm) and poly(PFPA) as core‐forming block are synthesized at room temperature via RAFT upon UV‐initiation and use of redox initiator couples, respectively. Cross‐linking of reactive poly(PFPA) cores and coronas enables imaging via AFM and electron microscopy. Polymerization‐induced thermal self‐assembly of poly(NIPAm)‐block‐poly(PFPA) nanoparticles shows linear relationship between particle size and degree of polymerization. [ABSTRACT FROM AUTHOR]

C1 polymerization, poly(propargyl 2-ylidene-acetate) (PPA), post-polymerization modification. [Display omitted] • C1 polymerization of propargyl 2-diazoacetate in the presence of low valence Rh-catalysts. • Well-defined polymethylenes and their subsequent post-modification were achieved. • Polymers were efficiently post-modified via CuAAC. Rhodium(I)-catalyzed C1 polymerization of propargyl 2-diazoacetate was conducted for the first time resulting in a novel functional polymethylene derivative, poly(propargyl 2-ylidene-acetate), which is suitable for a subsequent post-polymerization modification under mild reaction conditions via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The post-modification reaction results in quantitative conversions, and provides an efficient and general route for the selective post-modification of C1 polymers with a variety of azide compounds. The structure of the poly(propargyl 2-ylidene-acetate) was confirmed and characterized by NMR, FT-IR, and GPC techniques. Upon comparison with results on post-polymerization modification of the corresponding C2 polymer, poly(propargyl acrylate), no obvious influence on the reactivity towards the post-modification of acetylene group on the C1 polymer precursor was observed. Noteworthy, the introduction of pentafluorophenyl azide facilitated a subsequent second modification via the Para-Fluoro-Thiol reaction (PFTR). Accordingly, cascade post-modifications of C1 polymers yielded novel polymethylenes that are not accessible by direct C1 polymerization. [ABSTRACT FROM AUTHOR]

A seriesof poly(pentafluorophenyl (methyl)acrylates)-block-poly(ethylene oxide) with o-nitrobenzyl ester photocleavablejunctions (PPFP(M)A-hv-PEO) were synthesized by RAFTpolymerization. The block copolymers were used to fabricate thin filmsand fibers by spin-coating and electrospinning, respectively. Aftersolvent annealing, UV exposure, and washing with methanol/water toremove the minor PEO block, nanoporous structures were obtained. Boththe porous thin films and fibers remained reactive to amine substitutionof the pentafluorophenyl esters under mild conditions, which was confirmedby XPS, fluorescence confocal microscopy, FT-IR, and contact anglemeasurements. [ABSTRACT FROM AUTHOR]