RAFT polymerization and thio‐bromo substitution: An efficient way towards well‐defined glycopolymers

Despite an increasing effort to design well‐defined glycopolymers, the convenient synthesis of polymers with higher DPs (>100) and without tedious protection and deprotection steps remains a challenge. Combining the reversible addition fragmentation transfer (RAFT) polymerization and the efficient substitution of primary bromo groups by thiols, we were able to synthesize a set of well‐defined glycopolymers with DPs of up to 115. With the polymerization of the highly reactive monomer (2‐bromoethyl)‐acrylate polymers with low dispersities were obtained that could efficiently be functionalized with various sugar thiol(ate)s. In particular, derivatives of d ‐glucose, d ‐galactose, and d ‐mannose gave excellent degrees of functionalization close to quantitative conversion using only a slight excess of the thiol. This atom efficient synthesis can even be applied for copolymers with acid or base labile components due to the use of unprotected sugar moieties and, hence, the lack of further deprotection steps. Binding studies with the lectin concanavalin A and the subsequent competition studies with α‐d ‐methyl‐mannopyranose (αMeMan) proved the effective binding of these derivatives and revealed a DP‐ and carbohydrate‐dependent clustering and dissolution. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3617–3626     

Synthesis and characterizations of hemiditactic homopolymers derived of poly(3‐allyl‐3‐methylmalic acid): An example of a new class of polymer's ditacticity

A number of works have been focused on the study of polymers microtacticity and the probability of iso‐, syndio‐, and atactic arrangement of monomers such as polypropylene and poly(methacrylic esters) before the 1980s. This type of study was fewer in the last four decades despite the importance of stereochemical knowledge of macromolecules in the biomedical field. NMR analysis was the invaluable tool for the study of stereochemistry. This work detailed the synthesis and the physicochemical and microtacticity characterizations of new semicrystalline and amorphous polyesters, poly(3‐allyl‐3‐methylmalic acid) (PAlMMLA) derivatives which are part of the poly(malic acid) family. This polymer is biodegradable and biocompatible. It can also be chemically modified for a possible combination with bioactive molecules. It can be synthesized from chiral product leading a stereoregular and semicrystalline structure. In the case of a racemic starting product, the obtained macromolecular structure is amorphous. Semi‐crystalline polyester presented a highly diisotactic structure. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2408–2418     

Stimuli‐responsive amphiphilic PDMAEMA‐b‐PLMA copolymers and their cationic and zwitterionic analogs

In this work, the synthesis and characterization of novel amphiphilic diblock copolymers of poly(2‐dimethylamino ethyl methacrylate)‐b‐poly(lauryl methacrylate), PDMAEMA‐b‐PLMA, using the reversible addition‐fragmentation chain transfer (RAFT) polymerization technique, are reported. The diblocks were successfully derivatized to cationic and zwitterionic block polyelectrolytes by quaternization and sulfobetainization of the PDMAEMA block, respectively. Furthermore, their molecular and physicochemical characterization was performed by using characterization techniques such as NMR and FTIR, size exclusion chromatography, light scattering techniques, and transmission electron microscopy. The structure of the diblock micelles, their behavior, and properties in aqueous solution were investigated under the effect of pH, temperature, and ionic strength, as PDMAEMA and its derivatives are stimuli‐responsive polymers and exhibit responses to variations of at least one of these physicochemical parameters. These new families of stimuli‐responsive block copolymers respond to changes of their environment giving interesting nanostructures, behavioral motifs, and properties, rendering them useful as nanocarriers for drug delivery and gene therapy. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 598–610     

Direct arylation polymerization toward ultra‐low bandgap poly(thienoisoindigo‐alt‐diketopyrrolepyrrole) conjugated polymers: The effect of β‐protection on the polymerization and properties of the polymers

Direct arylation polymerization between derivatives of dibromodiketopyrrolopyrrole (DPP) and thienoisoindigo (TIIG) resulted in two π‐conjugated copolymers with average molecular weights up to 24.0 kDa and bandgaps as low as 0.8 eV. The structural analysis of the obtained two polymers revealed well‐defined alternating conjugation backbones without obvious structural defects. The introduction of hexyl‐group in the β‐position of thiophene rings in the DPP units not only reduces the bandgap of conjugated polymer compared to a similar polymer containing bare‐thiophene flanked DPP but also affects polymer morphology in thin films. P‐type charge‐transport characteristics were observed for two polymers in organic field‐effect transistors with comparable hole mobilities. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3205–3213     

Alkynylation of Bio‐Based 5‐Hydroxymethylfurfural to Connect Biomass Processing with Conjugated Polymers and Furanic Pharmaceuticals

Acetylene‐functionalized platform chemicals were synthesized from biomass‐derived 5‐hydrohymethylfurfural (HMF). Demanding mono‐ and bis‐ethynylfurans were obtained in high yields (89–99 %). Applications of these products in the synthesis of smart organic conjugated materials and pharmaceuticals were examined in a series of transformations. Conjugated polyacetylenic polymers with morphology control have been prepared by incorporation of the HMF core.     

Direct arylation polymerization toward a narrow bandgap donor–acceptor conjugated polymer of alternating 5,6‐difluoro‐2,1,3‐benzothiadiazole and alkyl‐quarternarythiophene: From synthesis,optoelectronic properties to devices

ABSTRACT: Direct arylation polymerization (DAP) enabled facile synthesis of a narrow bandgap donor–acceptor conjugated polymer (PDFBT‐Th₄) composed of alternating 5,6‐difluoro‐2,1,3‐benzothiadiazole and alkyl‐quaternarythiophene. The optimized reaction condition of DAP catalyzed with Pd(OAc)₂/(o‐MeOPh)₃P/PivOH/K₂CO₃ in o‐xylene led to the target polymer with a number‐average molecular weight (M_n) of 14.6 kDa without noticeable homocoupling or β‐branching defects. UV‐vis absorption spectra of PDFBT‐Th₄ indicate strong interchain aggregation in films. While the C‐H selectivity and the alternating polymer structure of PDFBT‐Th₄ synthesized via DAP are comparable to those of the same type polymers synthesized via Stille coupling, the batch of PDFBT‐Th₄ synthesized via optimal DAP, despite its lower M_n, showed higher hole mobility in field effect transistors and larger power conversion efficiency in organic solar cell devices. These results further demonstrate the promising potential of DAP for efficient synthesis of high‐performance D‐A conjugated polymers for broad optoelectronic applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1869–1879     

A di‐tert‐butyl acrylate monomer for controlled radical photopolymerization

A new di‐tert‐butyl acrylate (diTBA) monomer for controlled radical polymerization is reported. This monomer complements the classical use of tert‐butyl acrylate (TBA) for synthesis of poly(acrylic acid) by increasing the density of carboxylic acids per repeat unit, while also increasing the flexibility of the carboxylic acid side‐chains. The monomer is well behaved under Cu(II)‐mediated photoinduced controlled radical polymerization and delivers polymers with excellent chain‐end fidelity at high monomer conversions. Importantly, this new diTBA monomer readily copolymerizes with TBA to further the potential for applications in areas such as dispersing agents and adsorbents. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 801–807     

Vinyl‐terminated side‐chain liquid‐crystalline polyethers containing mesogenic benzylideneaniline moieties

The synthesis of two vinyl‐terminated side‐chain liquid‐crystalline polyethers containing benzylideneaniline moieties as mesogenic cores was approached in two different ways: by chemically modifying poly(epichlorohydrin) with suitable mesogenic acids or by polymerizing analogous glycidyl ester or glycidyl ether derivatives. In all the conditions tested, the first approach led to materials in which the imine group was hydrolyzed. The second approach led to the desired polymers PG2a and PG2b , but only from the glycidyl ether derivatives and when the initiator was the system that combined polyiminophosphazene base t‐Bu‐P₄ and 3,5‐di‐t‐butylphenol. These polymers were chemically characterized by IR and ¹H and ¹³C NMR spectroscopies. The estimated degrees of polymerization ranged from 30 to 36. The liquid crystalline behavior of the synthesized polymers was studied by differential scanning calorimetry, polarized optical microscopy (POM) and X‐ray diffraction. Both polymers behave like liquid crystals and exhibited a single mesophase, which was recognized as a smectic C mesophase, probably with a bilayer arrangement, i.e., a smectic C₂ mesophase. The crosslinking of both polymers was performed with dicumyl peroxide as initiator, which led to liquid crystalline thermosets. POM and X‐ray diffraction confirmed that the mesophase organization mantained on the crosslinked materials. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1877–1889, 2006     

Lignin‐based polymers via graft copolymerization

Lignin is an important source of synthetic materials because of its abundance in nature, low cost, stable supply, and no competition to the human food supply. Lignin, a cross‐linked phenolic polymer, contains a large number of aromatic groups that can be used as a substitute for petroleum‐based aromatic fine chemicals. However, modification of lignin is necessary for its application in advanced materials due to its chemically inert nature and structural complexity. Polymeric modification of lignin via graft copolymerization represents an important avenue for modification because this method forms stable covalent bond linkages between lignin and synthetic functional polymers. In this review, we discuss recent synthetic strategies toward polymeric modification of lignin using graft copolymerization and the special properties and applications of the produced lignin copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3515–3528     

Degradation of poly(β‐amino ester) gels in alcohols through transesterification: Method to conjugate drugs to polymer matrices

Poly(β amino ester) (PβAE) polymers have received growing attention in the literature, owing to their ease of synthesis, versatile co‐monomer selection, and highly tunable degradation kinetics. As such, they have shown extensive potential in many biomedical applications as well. In this work, it is demonstrated for the first time that PβAE polymers containing primary and secondary amine groups can undergo degradation by primary alcohols via transesterification mechanism. While this work emphasizes an important aspect of solvent compatibility of these networks, it also represents an interesting, simple mechanism for post synthesis drug incorporation, with riboflavin conjugation being demonstrated as a model compound. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2019–2026     

Dual stimuli‐responsive polyamines derived from modified N‐vinylpyrrolidones through CuAAC click chemistry

The synthesis via copper(I)‐catalyzed azide alkyne cycloaddition (CuAAC) of three new monomer derivatives of N‐vinyl‐2‐pyrrolidone (VP) carrying cyclic pyrrolidine, piperidine, and piperazine groups and the corresponding copolymers with unmodified VP is shown. The systems bearing pyrrolidine and piperidine displayed both thermo‐ and pH‐response, which has not been reported previously for a polymer with polyvinylpyrrolidone (PVP) backbone. A broad modulation of the LCST with the copolymer composition and pH was observed in a temperature range 0–100 °C. The polymers carrying piperazine exhibited broad buffering regions and no thermosensitivity. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1098–1108     

“Click” chemistry for in situ formation of thermoresponsive P(NIPAAm‐co‐HEMA)‐based hydrogels

The strategy for in situ chemical gelation of poly(N‐isopropylacrylamide‐co‐hydroxylethyl methacrylate) [P(NIPAAm‐co‐HEMA)]‐based polymers was demonstrated. Two types of new P(NIPAAm‐co‐HEMA) derivatives with alkyne and azide pendant groups, respectively, were prepared. When the solutions of the two derivatives were mixed together, a crosslinking reaction, a type of Huisgen's 1,3‐dipolar azide‐alkyne cycloaddition, in the presence of Cu(I) catalyst occurs. The morphology, equilibrium swelling ratio, swelling kinetics, and temperature response kinetics of the in situ gelated hydrogels were studied. In comparison with the conventional PNIPAAm hydrogel, because of the spatial hindrance of polymeric chains, the resulted hydrogels had a macroporous structure as well as a fast shrinking rate. The strategy described here presents a potential alternative to the traditional synthesis techniques for the in situ formation of thermoresponsive hydrogels. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5263–5277, 2008     

Synthesis and radical ring‐opening polymerization of vinylcyclopropanes derived from amino acids with hydrophobic moieties

Six 1,1‐disubstituted vinylcyclopropanes (VCP) were synthesized from glycine and amino acids bearing hydrophobic moieties, l ‐alanine, l ‐valine, l ‐leucine, l ‐isoleucine, and l ‐phenylalanine. These VCP derivatives efficiently underwent radical ring‐opening polymerization to afford the corresponding polymers bearing trans‐vinylene moiety in the main chains and the amino acid‐derived chiral moieties in the side chains. The polymers were film‐formable, and in the films of polymers bearing the glycine‐ and alanine‐derived side chains, presence of hydrogen bonding was confirmed by IR analysis. Thermogravimetric analysis of the polymers revealed that the temperatures of 5% weight loss were higher than 300 °C. Differential scanning calorimetry clarified that the polymers were amorphous ones showing glass transition temperatures in a range of 48–80 °C. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3996–4002     

Chiral oxazoline substituted optically active poly(m‐phenylene)s: Synthesis and coupling polymerizations of (S)‐4‐benzyl‐2‐(3,5‐dihalidephenyl) oxazoline using transition metal catalysts

Optically active poly(m‐phenylene)s substituted with chiral oxazoline derivatives have been synthesized by the nickel‐catalyzed Yamamoto coupling reaction of optically active (S)‐4‐benzyl‐2‐(3,5‐dihalidephenyl)oxazoline derivatives (X = Br or I). The structures and chiroptical properties of the polymers were characterized by spectroscopic methods and thermal gravimetric analyses. The polymers showed higher absolute optical specific rotation values than their corresponding monomer, and showed a Cotton effect at transition region of conjugated main chain. The optical activities of the polymers should be attributed to the higher order structure such as helical conformations. Moreover, the helical conformation could be induced by addition of metal salts into polymer solutions. The polymers showed good thermal stabilities, which was attributable to the oxazoline side chains. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Regioirregular ambipolar naphthalenediimide‐based alternating polymers: Synthesis,characterization, and application in field‐effect transistors

In this work, we report the synthesis, characterization, and application of two regioirregular naphthalenediimide (NDI)‐based alternating conjugated polymers, namely P1 and P2 , in which nitrile‐substituted moiety, 2,3‐bis(thiophen‐2‐yl)acrylonitrile and NDI moiety act as donor and acceptor unit, respectively. The two regioirregular polymers possess low‐lying LUMO energy levels of ?3.92 eV for P1 and ?3.96 eV for P2 . Both polymers possess typical dual‐band UV?Vis?NIR absorption profiles of NDI‐based polymers, and show broadened and red‐shifted absorption spectra in the solid state compared with those in solutions. Field‐effect transistor devices with top‐gate bottom‐contact configuration were used to evaluate the polymers' semiconducting properties. The two polymers exhibited promising and air‐stable ambipolar charge transport characteristics. Thin film microstructure investigations (AFM and 2D‐GIXRD) suggest both polymers formed continuous and smooth thin films, and adopted predominantly face‐on molecular packing in the solid state. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3627–3635     

Visible light‐induced RAFT polymerization of methacrylates with benzaldehyde derivatives as organophotoredox catalysts

The benzaldehyde derivatives, such as 2,4‐dimethoxy benzaldehyde (PC1) and p‐anisaldehyde (PC2), were successfully used as photoredox catalysts (PCs) in combination with typical RAFT agent 4‐cyano‐4‐(phenylcarbonothioylthio)pentanoic acid (CTP) for the controlled photoinduced electron transfer RAFT polymerization (PET‐RAFT) of methyl methacrylate (MMA) and benzyl methacrylate (BnMA) at room temperature. The kinetics of the polymerizations showed first order with respect to monomer conversions. Besides, the average number molecular weights (M_n) of the produced polymers increased linearly with the monomer conversions and kept relatively narrow polydispersity (PDI = M_w/M_n). For example, the M_n of PMMA increased from about 3400 to 17,300 g mol⁻¹ with the increasing in monomer conversion from 11% to 85%, and the PDI maintained around 1.36. The living features of polymerizations with the PC1 and PC2 as catalysts have also been further supported by chain extension and synthesis of PMMA‐b‐PBnMA diblock copolymer. As a result, the simplicity and efficiency of benzaldehyde derivatives catalyzed PET‐RAFT polymerization have been demonstrated under mild conditions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 229–236     

Microwave‐assisted solvent‐free synthesis of novel benzoxazines: A faster and environmentally friendly route to the development of bio‐based thermosetting resins

Microwave‐assisted organic synthesis (MAOS) is a well‐established technique that has been used in the enhancement of chemical reactions. Here, the versatility of MAOS is explored describing an environmentally friendly one‐pot route to novel bio‐based benzoxazines under solvent‐free conditions. The lignin derivative, guaiacol, along with paraformaldehyde and different conjugated and nonconjugated amines are successfully fused into guaiacol‐derived 3,4‐dihydro‐2H‐1,3‐benzoxazines. The reactions conducted under microwave irradiation are completed much faster than those under traditional heating, reducing the reaction time from hours to only 6 min, with good yields. The chemical structures of novel benzoxazines are confirmed by ¹H and ¹³C NMR spectroscopy, FTIR, and HR‐MS. The thermal behavior of the resins are evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), showing that these polymers have good thermal stability and wide processing‐window, with onset temperature of polymerization above 230 °C. These results indicate dramatic improvement over the traditional methodologies for the production of this class of resins, which are usually obtained by time‐consuming procedures and in the presence of toxic solvents. Therefore, MAOS can be considered a green and efficient strategy for the synthesis of eco‐friendly benzoxazines. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3534–3544     

Photovoltaic response to structural modifications on a series of conjugated polymers based on 2‐aryl‐2H‐benzotriazoles

The synthesis, characterization, and photovoltaic properties of a series of four conjugated polymers containing 2‐aryl‐2H‐benzotriazoles and “bis(thiopheno)dialkylfluorenes” is described. The polymers were obtained via Suzuki‐polycondensation and comprise alternating electron rich and electron poor building blocks. The impact of systematic structural changes on the electronic and morphological properties and device efficiencies were studied. Application of these polymers as light‐harvesting and electron‐donating materials in organic solar cells using PCBM derivatives as electron accepting materials resulted in power conversion efficiencies up to 1.8%. Both the properties of the pristine polymers and the device performance show that the impact of the substitution farther‐off the backbone is negligible while substitution directly on the backbone has a major impact. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Proton‐conducting polymers based on benzimidazoles and sulfonated benzimidazoles

A sulfonated derivative of polybenzimidazole is reported, and its properties are analyzed in comparison with related polybenzimidazole proton‐conducting materials. Poly(2,5‐benzimidazole), poly(m‐phenylenebenzobisimidazole), and poly[m‐(5‐sulfo)‐phenylenebenzobisimidazole] were prepared by condensation of the corresponding monomers in polyphosphoric acid. Several adducts of these polymers with phosphoric acid were prepared. The resulting materials were characterized by chemical analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis; also, the dc conductivity of doped and undoped derivatives was measured. Similar to what has been observed for the commercial polybenzimidazole polymer (also examined here for comparison), the title polymers exhibit high thermal stability. Furthermore, their doping with phosphoric acid leads to a significant increase in conductivity from less than 10^?11 Scm^?1 for the undoped polymers to 10^?4 Scm^?1 (both at room temperature) for their acid‐loaded derivatives. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3703–3710, 2002     

Synthesis and postfunctionalization of well‐defined star polymers via “double” click chemistry

In this article, the synthesis and the functionalization of well‐defined, narrow polydispersity (polydispersity index < 1.2) star polymers via reversible addition‐fragmentation chain transfer polymerization is detailed. In this arm first approach, the initial synthesis of a poly(pentafluorophenyl acrylate) polymer, and subsequent, cross‐linking using bis‐acrylamide to prepare star polymers, has been achieved by reversible addition fragmentation chain transfer polymerization. These star polymers were functionalized using a variety of amino functional groups via nucleophilic substitution of pentafluorophenyl activated ester to yield star polymers with predesigned chemical functionality. This approach has allowed the synthesis of star glycopolymer using a very simple approach. Finally, the core of the stars was modified via thiol‐ene click chemistry reaction using fluorescein‐o‐acrylate and DyLigh 633 Maleimide. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011