Synthesis,characterization, and micellization of PCL‐g‐PEG copolymers by combination of ROP and “Click” chemistry via “Graft onto” method

Biodegradable and biocompatible PCL‐g‐PEG amphiphilic graft copolymers were prepared by combination of ROP and “click” chemistry via “graft onto” method under mild conditions. First, chloro‐functionalized poly(ε‐caprolactone) (PCL‐Cl) was synthesized by the ring‐opening copolymerization of ε‐caprolactone (CL) and α‐chloro‐ε‐caprolactone (CCL) employing scandium triflate as high‐efficient catalyst with near 100% monomer conversion. Second, the chloro groups of PCL‐Cl were quantitatively converted into azide form by NaN₃. Finally, copper(I)‐catalyzed cycloaddition reaction was carried out between azide‐functionalized PCL (PCL‐N₃) and alkyne‐terminated poly(ethylene glycol) (A‐PEG) to give PCL‐g‐PEG amphiphilic graft copolymers. The composition and the graft architecture of the copolymers were characterized by ¹H NMR, FTIR, and GPC analyses. These amphiphilic graft copolymers could self‐assemble into sphere‐like aggregates in aqueous solution with diverse diameters, which decreased with the increasing of grafting density. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and functionalization of dendron‐polymer conjugate based hydrogels via sequential thiol‐ene “click” reactions

Fabrication and functionalization of hydrogels from well‐defined dendron‐polymer‐dendron conjugates is accomplished using sequential radical thiol‐ene “click” reactions. The dendron‐polymer conjugates were synthesized using an azide‐alkyne “click” reaction of alkene‐containing polyester dendrons bearing an alkyne group at their focal point with linear poly(ethylene glycol)‐bisazides. Thiol‐ene “click” reaction was used for crosslinking these alkene functionalized dendron‐polymer conjugates using a tetrathiol‐based crosslinker to provide clear and transparent hydrogels. Hydrogels with residual alkene groups at crosslinking sites were obtained by tuning the alkene‐thiol stoichiometry. The residual alkene groups allow efficient postfunctionalization of these hydrogel matrices with thiol‐containing molecules via a subsequent radical thiol‐ene reaction. The photochemical nature of radical thiol‐ene reaction was exploited to fabricate micropatterned hydrogels. Tunability of functionalization of these hydrogels, by varying dendron generation and polymer chain length was demonstrated by conjugation of a thiol‐containing fluorescent dye. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 926–934     

Synthesis and characterization of star graft copolymers with asymmetric mixed “V‐shaped” side chains via “click” chemistry on a hyperbranched polyglycerol core

The star graft copolymers composed of hyperbranched polyglycerol (HPG) as core and well defined asymmetric mixed “V‐shaped” identical polystyrene (PS) and poly(tert‐butyl acrylate) as side chains were synthesized via the “click” chemistry. The V‐shaped side chain bearing a “clickable” alkyne group at the conjunction point of two blocks was first prepared through the combination of anionic polymerization of styrene (St) and atom transfer radical polymerization of tert‐butyl acrylate (tBA) monomer, and then “click” chemistry was conducted between the alkyne groups on the side chains and azide groups on HPG core. The obtained star graft copolymers and intermediates were characterized by gel permeation chromatography (GPC), GPC equipped with a multiangle laser‐light scattering detector (GPC‐MALLS), nuclear magnetic resonance spectroscopy and fourier transform infrared. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1308–1316, 2009     

Synthesis of a novel graft copolymer with hyperbranched poly(glycerol) as core and “Y”‐shaped polystyrene‐b‐poly(ethylene oxide)2 as side chains

The graft copolymers composed of “Y”‐shaped polystyrene‐b‐poly(ethylene oxide)₂ (PS‐b‐PEO₂) as side chains and hyperbranched poly(glycerol) (HPG) as core were synthesized by a combination of “click” chemistry and atom transfer radical polymerization (ATRP) via “graft from” and “graft onto” strategies. Firstly, macroinitiators HPG‐Br were obtained by esterification of hydroxyl groups on HPG with bromoisobutyryl bromide, and then by “graft from” strategy, graft copolymers HPG‐g‐(PS‐Br) were synthesized by ATRP of St and further HPG‐g‐(PS‐N₃) were prepared by azidation with NaN₃. Then, the precursors (Bz‐PEO)₂‐alkyne with a single alkyne group at the junction point and an inert benzyl group at each end was synthesized by sequentially ring‐opening polymerization (ROP) of EO using 3‐[(1‐ethoxyethyl)‐ethoxyethyl]‐1,2‐propanediol (EEPD) and diphenylmethylpotassium (DPMK) as coinitiator, termination of living polymeric species by benzyl bromide, recovery of protected hydroxyl groups by HCl and modification by propargyl bromide. Finally, the “click” chemistry was conducted between HPG‐g‐(PS‐N₃) and (Bz‐PEO)₂‐alkyne in the presence of N,N,N′,N″,N”‐pentamethyl diethylenetriamine (PMDETA)/CuBr system by “graft onto” strategy, and the graft copolymers were characterized by SEC, ¹H NMR and FTIR in details. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Sequential functionalization of janus‐type dendrimer‐like poly(ethylene oxide)s with camptothecin and folic acid

Janus‐type dendrimer‐like poly(ethylene oxide)s (PEOs) of 1st, 2nd, and 3rd generation carrying terminal hydroxyl functions on one side and cleavable ketal groups on the other were used as substrates to conjugate folic acid as a folate receptor and camptothecin (CPT) as a therapeutic drug in a sequential fashion. The conjugation of both FA and CPT was accomplished by “click chemistry” based on the 1,3 dipolar cycloaddition coupling reaction. First, the hydroxyl functions present at one face of Janus‐type dendrimer‐like PEOs were transformed into alkyne groups through a simple Williamson‐type etherification reaction. Next, the ketals carried by the other face of the dendrimer‐like PEOs were hydrolyzed, yielding twice as many hydroxyls which were subsequently subjected to an esterification reaction using 2‐bromopropionic bromide. Before substituting azides for the bromide of 2‐bromopropionate esters just generated in the presence of NaN₃, an azido‐containing amidified FA derivative was reacted through click chemistry with alkyne functions introduced on the other face of the dendrimer‐like PEOs. A purposely designed alkyne‐functionalized biomolecule derived from CPT was conjugated to the azido functions carried by the dendritic PEOs by a second “click reaction.” In this case, twice as many CPT as FA moieties were finally conjugated to the two faces of the Janus‐type dendrimer‐like PEOs, the numbers of folate and CPT introduced being 2 and 4, 4 and 8, and 8 and 16 for samples of 1st, 2nd, and 3rd generation, respectively (route A). An alternate route for functionalizing the dendrimer‐like PEO of 1st generation consisted, first, in conjugating the azido‐containing CPT onto the alkyne groups present on one face of the dendritic PEO scaffold. The alkyne‐functionalized FA was further introduced by click chemistry after the bromides of 2‐bromopropionate esters were chemically transformed into azido groups. The corresponding prodrug thus contains 2 CPT and 4 FA external moieties (route B). Every reaction step product was thoroughly characterized by ¹H NMR spectroscopy. A preliminary investigation into the water solution properties of these functionalized dendritic PEOs is also presented. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Copper(0)‐catalyzed one‐pot synthesis of ABC triblock copolymers via the combination of single electron transfer nitroxide radical coupling reaction and “click” chemistry

The synthesis of ABC triblock copolymers were accomplished by Cu(0)‐catalyzed one‐pot strategy combining single electron transfer‐nitroxide radical coupling (SET‐NRC) reaction with “click” chemistry. First, the precursors α,ω‐heterofunctionalized poly(ethylene oxide) (PEO) with a 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) group and an alkyne group, polystyrene (PS), and poly(tert‐butyl acrylate) (PtBA) with bromine or azide end group were designed and synthesized, respectively. Then, the one‐pot coupling reactions between these precursors were carried out in the system of Cu(0)/Me₆TREN: The SET‐NRC reaction between bromine group and nitroxide radical group, subsequently click coupling between azide and alkyne group. It was noticeable that Cu(I) generated from Cu(0) by SET mechanism was utilized to catalyze click chemistry. To estimate the effect of Cu(0) on the one‐pot reaction, a comparative analysis was performed in presence of different Cu(0) species. The result showed that Cu(0) with more active surface area could accelerate the one‐pot reaction significantly. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Macrocyclization of polymers via ring‐closing metathesis and azide/alkyne‐“click”‐reactions: An approach to cyclic polyisobutylenes

The end‐to‐end cyclization of telechelic polyisobutylenes (PIB's) toward cyclic polyisobutylenes is reported, using either ring‐closing metathesis (RCM) or the azide/alkyne‐“click”‐reaction. The first approach uses bisallyl‐telchelic PIB's (M_n = 1650, 3680, 9770 g mol^?1) and Grubbs 1st‐, 2nd‐, and 3rd‐generation catalyst leading to cyclic PIB's in 60–80% yield, with narrow polydispersities (M_w/M_n = 1.25). Azide/alkyne‐“click”‐reactions of bisalkyne‐telechelic PIB's (M_n = 3840 and 9820 g mol^?1) with excess of 1,11‐diazido‐undecane leads to the formation of mixtures of linear/cyclic PIB's under formation of oligomeric cycles. Subsequent reaction of the residual azide‐moieties in the linear PIB's with excess of alkyne‐telechelic PEO enables the chromatographic removal of the resulting linear PEO‐PIB‐block copolymers by column chromatography. Thus pure cyclic PIB's can be obtained using this double‐“click”‐method, devoid of linear contaminants. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 671–680, 2010     

Combining “click” chemistry and step‐growth polymerization for the generation of highly functionalized polyesters

Aliphatic polyesters bearing pendant alkyne groups were successfully prepared by step‐growth polymerization of different building blocks such as adipic acid and succinic acid in combination with an acetylene‐based diol, 2‐methyl‐2‐propargyl‐1,3‐propanediol, besides 1,4‐butanediol and ethylene glycol. It was demonstrated that the alkyne groups survive the high reaction temperatures (200 °C) in the presence of a radical inhibitor. The alkyne loading has been tuned by the ratio of the different monomers used, up to 25 mol % of alkyne groups. Subsequently, the alkyne groups have been reacted with azides by the copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction, a popular type of “click” chemistry. “Click” reactions have been performed quantitatively in the presence of benzyl azide and azide‐terminated poly(ethylene glycol), yielding brush copolymers in the latter case. Kinetic investigations about this click reaction have been performed by means of on‐line Fourier transform mid‐infrared spectroscopy, which was reported for the first time in the field of the click chemistry research. A whole range of functionalized polyesters, based on poly(ethylene succinate) and poly(butylene adipate), is available, the properties of which can be tailored by choosing the appropriate azide compound. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6552–6564, 2008     

Synthesis of ABCD 4‐Miktoarm star‐shaped quarterpolymers by combination of the “click” chemistry with multiple polymerization mechanism

Well‐defined ABCD 4‐Miktoarm star‐shaped quarterpolymers of [poly(styrene)‐poly(tert‐butyl acrylate)‐poly(ethylene oxide)‐poly(isoprene)] [star(PS‐PtBA‐PEO‐PI)] were successfully synthesized by the combination of the “click” chemistry and multiple polymerization mechanism. First, the poly(styryl)lithium (PS^?Li⁺) and the poly(isoprene)lithium (PI^?Li⁺) were capped by ethoxyethyl glycidyl ether (EEGE) to form the PS and PI with both an active ω‐hydroxyl group and an ω′‐ethoxyethyl‐protected hydroxyl group, respectively. After these two hydroxyl groups were selectively modified to propargyl and 2‐bromoisobutyryl group for PS, the resulted PS was used as macroinitiator for ATRP of tBA monomer and the diblock copolymer PS‐b‐PtBA with a propargyl group at the junction point was achieved. Then, using the functionalized PI as macroinitiator for ROP of EO monomer and bromoethane as blocking agent, the diblock copolymer PI‐b‐PEO with a protected hydroxyl group at the conjunction point was synthesized. After the hydrolysis, the recovered hydroxyl group of PI‐b‐PEO was modified to bromoacetyl and then azide group successively. Finally, the “click” chemistry between them was proceeded smoothly. The obtained star‐shaped quarterpolymers and intermediates were characterized by ¹H NMR, FT‐IR, and SEC in detail. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2154–2166, 2008     

Synthesis of ABCD 4‐miktoarm star polymers by combination of RAFT,ROP, and “Click Chemistry”

The ABCD 4‐miktoarm star polymers based on polystyrene (PS), poly(ε‐caprolactone) (PCL), poly(methyl acrylate) (PMA), and poly(ethylene oxide) (PEO) were synthesized and characterized successfully. Using the mechanism transformation strategy, PS with three different functional groups (i.e., hydroxyl, alkyne, and trithiocarbonate), PS‐HEPPA‐SC(S)SC₁₂H₂₅, was synthesized by the reaction of the trithiocarbonate‐terminated PS with 2‐hydroxyethyl‐3‐(4‐(prop‐2‐ynyloxy)phenyl) acrylate (HEPPA) in tetrahydrofuran (THF) solution. Subsequently, the ring‐opening polymerization (ROP) of ε‐caprolactone (CL) was carried out in the presence of stannous(II) 2‐ethylhexanoate and PS‐HEPPA‐SC(S)SC₁₂H₂₅, and then the PS‐HEPPA(PCL)‐SC(S)SC₁₂H₂₅ obtained was used in reversible addition‐fragmentation chain transfer (RAFT) polymerization of methyl acrylate (MA) to produce the ABC 3‐miktoarm star polymer, S(PS)(PCL)(PMA) carrying an alkyne group. The ABCD 4‐miktoarm star polymer, S(PS)(PCL)(PMA)(PEO) was successfully prepared by click reaction of the alkyne group on the HEPPA unit with azide‐terminated PEO (PEO‐N₃). The target polymer and intermediates were characterized by NMR, FTIR, GPC, and DSC. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6641–6653, 2008     

Photo‐initiated thiol–ene “click” hydrogels from RAFT‐synthesized poly(N‐isopropylacrylamide)

Despite the efficiency and robustness of the widely used copper‐catalyzed 1,3‐dipolar cycloaddition reaction, the use of copper as a catalyst is often not attractive, particularly for materials intended for biological systems. The use of photo‐initiated thiol‐ene as an alternative “click” reaction to synthesize “model networks” is investigated here. Poly(N‐isopropylacrylamide) precursors were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization and were designed to have trithiocarbonate moieties as end groups. This structure design provides opportunity for subsequent end‐group modifications in preparation for thiol‐ene “click.” Two reaction routes have been proposed and studied to yield thiol and ene moieties. The advantages and disadvantages of each reaction path were investigated to propose a simple but efficient route to prepare copper‐free “click” hydrogels. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4626–4636     

A new strategy for synthesis of “umbrella‐like” poly(ethylene glycol) with monofunctional end group for bioconjugation

A novel strategy was used to synthesize poly(ethylene glycol) (PEG) with “umbrella‐like” structure containing a single reactive group at the “handle” of the “umbrella”. 1‐(Bis(2‐hydroxyethyl)amino)‐3‐(1‐ethoxyethoxy)propan‐2‐ol was used to initiate the ring‐opening polymerization (ROP) of ethylene oxide (EO) in the presence of diphenylmethylpotassium (DPMK) to obtain three‐arm PEG (PEG3), then terminated by benzyl bromide or ethyl bromide. The resultant PEG3 was hydrolyzed to generate hydroxyl group at the conjunction point, and the second step ROP of EO was carried out using PEG3‐OH as macroinitiator in the presence of DPMK. The obtained four‐arm PEG (PEG4) contained a functional hydroxyl group at the end of the fourth arm, which could be easily modified to bioactive groups such as carboxyl, active ester, amino, etc. The well‐defined structure of “umbrella‐like” PEG was characterized by GPC, ¹H NMR, and MALDI‐TOF MS in detail. Propionic acid succinimidyl ester of PEG4 (10 kDa) was utilized for protein conjugation with interferon α‐2b. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Discrete macromolecular constructs via the Diels–Alder “Click” reaction

Functional polymeric materials with desired properties can be designed by precise control of macromolecular architectures. Over the recent years, click reactions have enabled efficient synthesis of a variety of polymers with different topologies via efficient polymer–polymer conjugations. While the copper catalyzed Huisgen type (3+2) dipolar cycloaddition between azide and alkyne has been widely used toward this goal, the Diels–Alder (DA) reaction offers an alternative click reaction that allow efficient macromolecular conjugations, oftentimes without the need of any additional reagent or catalyst. This article highlights, with illustrative examples, the power of the DA “click” reaction to efficiently synthesize a variety of different well‐defined macromolecular constructs in a modular fashion. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Heterograft copolymers of poly(ε‐caprolactone) prepared by combination of ATRA “grafting onto” and ATRP “grafting from” processes

This paper aims at reporting on the synthesis of a heterograft copolymer by combining the “grafting onto” process based on atom transfer radical addition (ATRA) and the “grafting from” process by atom transfer radical polymerization (ATRP). The statistical copolymerization of ε‐caprolactone (εCL) and α‐chloro‐ε‐caprolactone (αClεCL) was initiated by 2,2‐dibutyl‐2‐stanna‐1,3‐dioxepane (DSDOP), followed by ATRA of parts of the chlorinated units of poly(αClεCL‐co‐εCL) on the terminal double bond of α‐MeO,ω‐CH₂?CH? CH₂? CO₂‐poly(ethylene oxide) (PEO). The amphiphilic poly(εCL‐g‐EO) graft copolymer collected at this stage forms micelles as supported by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The unreacted pendant chloro groups of poly(εCL‐g‐EO) were used to initiate the ATRP of styrene with formation of copolymer with two populations of randomly distributed grafts, that is PEO and polystyrene. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6015–6024, 2006     

Preparation of comb‐like copolymers with amphiphilic poly(ethylene oxide)‐b‐polystyrene graft chains by combination of “graft from” and “graft onto” strategies

A novel method for preparation the comb‐like copolymers with amphihilic poly(ethylene oxide)‐block‐poly(styrene) (PEO‐b‐PS) graft chains by “graft from” and “graft onto” strategies were reported. The ring‐opening copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE) was carried out first using α‐methoxyl‐ω‐hydroxyl‐poly(ethylene oxide) (mPEO) and diphenylmethyl potassium (DPMK) as coinitiation system, then the EEGE units on resulting linear copolymer mPEO‐b‐Poly(EO‐co‐EEGE) were hydrolyzed and the recovered hydroxyl groups were reacted with 2‐bromoisobutyryl bromide. The obtained macroinitiator mPEO‐b‐Poly(EO‐co‐BiBGE) can initiate the polymerization of styrene by ATRP via the “Graft from” strategy, and the comb‐like copolymers mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐PS] were obtained. Afterwards, the TEMPO‐PEO was prepared by ring‐opening polymerization (ROP) of EO initiated by 4‐hydroxyl‐2,2,6,6‐tetramethyl piperdinyl‐oxy (HTEMPO) and DPMK, and then coupled with mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐PS] by atom transfer nitroxide radical coupling reaction in the presence of cuprous bromide (CuBr)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) via “Graft onto” method. The comb‐like block copolymers mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐(PS‐b‐PEO)] were obtained with high efficiency (≥90%). The final product and intermediates were characterized in detail. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1930–1938, 2009     

Pyrene functional poly(vinyl alcohol) by “click” chemistry

Side‐chain pyrene functional poly(vinyl alcohol) (PVA) was synthesized by using “click chemistry” strategy. First, partial tosylation of PVA with p‐toluene sulfonyl chloride were performed. The resulting PVA‐Ts polymer was then quantitatively converted into poly(vinyl alcohol)‐azide (PVA‐N₃) in the presence of NaN₃/DMF at 60 °C. Propargyl pyrene was prepared independently as a photoactive click component. Finally, azido functionalized PVA was coupled to propargyl pyrene with high efficiency by click chemistry. Incorporation of pyrene functionality in the resulting polymer was confirmed by spectral analysis. It is also shown that pyrene functionalized PVA (PVA‐Py) exhibited characteristic fluorescence properties and improved solubility in highly polar solvents such as water, DMSO, and DMF as well as less polar solvent such as THF compared with pristine PVA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1317–1326, 2009     

Dendronized polymers via Diels–Alder “click” reaction

A modular approach toward the synthesis of polymers containing dendron groups as side chains is developed using the Diels–Alder “click” reaction. For this purpose, a styrene‐based polymer appended with anthracene groups as reactive side chains was synthesized. First through third‐generation polyester dendrons containing furan‐protected maleimide groups at their focal point were synthesized. Facile, reagent‐free, thermal Diels–Alder cycloaddition between the anthracene‐containing polymer and latent‐reactive dendrons leads to quantitative functionalization of the polymer chains to afford dendronized polymers. The efficiency of this functionalization step was monitored using ¹H and ¹³C NMR spectroscopy and FTIR and UV–vis spectrometry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 410–416, 2010     

Synthesis of anionic carbosilane dendrimers via “click chemistry” and their antiviral properties against HIV

The synthesis and characterization of four families of anionic carbosilane dendrimers bearing carboxylate, phosphonate, naphthylsulfonate, and sulfate terminal groups prepared by cycloaddition of azide–alkyne catalyzed by copper (CuAAC) are presented here. For the preparation of these anionic carbosilane dendrimers, two strategies starting from azide‐terminated carbosilane dendrimers were followed: (i) click coupling of neutral alkynes followed by derivatization into anionic moieties or (ii) click coupling of anionic alkynes. Both strategies require different reaction conditions in order to accommodate the different substrate polarities. These anionic dendrimers, in general, do not present cell toxicity in vitro until concentration up to 20 µM. Therefore, they can be used in inhibition experiments in concentrations below this limit. We have observed that dendrimers bearing phosphonate groups possess poor anti‐HIV capabilities in vitro in PBMCs, while carboxylate dendrimers can reduce HIV infection levels moderately. On the other hand, sulfate and naphthylsulfonate dendrimers are powerful anti‐HIV agents and their antiviral activity is generation and concentration dependent. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1099–1112     

Synthesis and characterization of poly(ethylene oxide)/polylactide/poly(ethylene oxide) triblock copolymer

Poly(ethylene oxide/polylactide/poly(ethylene oxide) (PEO/PL/PEO) triblock copolymers, in which each block is connected by an ester bond, were synthesized by a coupling reaction between PL and PEO. Hydroxyl‐terminated PLs with various molecular weights were synthesized and used as hard segments. Hydroxyl‐terminated PEOs were converted to the corresponding acid halides via their acid group and used as a soft segment. Triblock copolymers were identified by Fourier transform infrared spectroscopy, ¹H NMR, and gel permeation chromatography. Differential scanning calorimetry (DSC) and X‐ray diffractometry of PEO/PL/PEO triblock copolymers suggested that PL and PEO blocks were phase‐separated and that the crystallization behavior of the PL block was markedly affected by the presence of the PEO block. PEO/PL/PEO triblock copolymers with PEO 0.75k had two exothermic peaks (by DSC), and both peaks were related to the crystallization of PL. According to thermogravimetric analysis, PEO/PL/PEO triblock copolymer showed a higher thermal stability than PL or PEO. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2545–2555, 2002     

Design of Well‐Defined Monofunctionalized Poly(3‐hexylthiophene)s: Toward the Synthesis of Semiconducting Graft Copolymers

The post‐functionalization of poly(3‐hexylthiophene) (P3HT) via various synthetic routes is reported. Well‐defined and monofunctionalized ω‐thiol‐terminated P3HT, ω‐carboxylic acid‐terminated P3HT, ω‐acrylate‐terminated P3HT, and ω‐methacrylate‐terminated P3HT are obtained in high yields through a straightforward procedure. From those, different novel P3HT‐based graft copolymers are synthesized following two routes: “grafting onto” and “grafting through” (macromonomer polymerization) methods. The synthesis of three types of graft copolymers is described. Each one has “rod” P3HT‐grafted side chains on a “coil” main chain, which can be polyisoprene, poly(vinyl alcohol), or poly(butyl acrylate). Each copolymer is characterized by size‐exclusion chromatography and NMR.