Electron-donating Monomer Research Articles

Benzodipyrrolidone-based donor-acceptor semiconducting polymers with high hole mobility and noncovalent conformational locks

Constructing highly coplanar polymer backbone plays an important role in boosting the carrier mobility of organic field effect transistors (OFETs) devices. In this study, based on noncovalent conformational locks strategy, we synthesized the electron-acceptor (A) monomer via introducing 3-dodecylthiophene on strong electron-deficient planar benzodipyrrolidone and the electron-donor (D) monomers containing different numbers (0–2) of fluorine atoms at different positon. A series of novel D-A copolymers, namely PBDP-F0, PBDP-F1 and PBDP-F2 with different backbone conformational locks through F⋯S and F⋯H–C noncovalent interactions, were obtained via Stille polycondensation. For the application in an organic field-effect transistor, all the polymers exhibited p-type charge transport characteristics and good performance with the highest hole mobilities as 0.24 cm2 V−1 s−1 for PBDP-F0, 0.87 cm2 V−1 s−1 for PBDP-F1 and 1.93 cm2 V−1 s−1 for PBDP-F2, respectively. AFM and GIXRD investigations indicated that all polymers take predominantly edge-on orientation packing mode because of the rigid and coplanar backbone conformation and the annealing films exhibited small π-π stacking distances of 3.73, 3.71 and 3.69 Å for PBDP-F0, PBDP-F1 and PBDP-F2 respectively. This work demonstrates that modified BDP-based D-A copolymers with conformational locks has a potential application in the high-performance semiconductor materials.

D-A non-equivalent random strategy to achieve donor polymers for stable organic solar cells with efficiency over 17%

High efficiency organic solar cells with great stability are crucial for future commercialization. Herein, a simple electron-donating monomer 2,6-dibromo-4,8-bis(octyloxy)benzo[1,2-b:4,5-b'] dithiophene (BDT-O) was synthesized as the third component to be introduced into the D-A backbone of PM6 by D-A non-equivalent random copolymerization. A series of wide-bandgap D-A-D-D1-type random terpolymer donors PM6-Ox (x = 5, 10, 30) were obtained, in which BDT-O served as the third component D1, fluorinated bis-2-ethylhexyl thiophene substituted benzodithiophene served as the D component and the typical 1,3-bis(4-(2-ethylhexyl) thiophen-2-yl)-5,7-bis(2-alkyl) benzo[1,2-c:4,5-c']dithiophene-4,8-dione was used as the A component. Morphological and photoelectronic characterizations are investigated to reveal the effects of BDT-O unit on the photovoltaic (PV) performances of polymers. Small content of BDT-O unit introduced into PM6 can effectively tune the absorption, energy levels and molecular arrangement of polymers for better solar light-harvesting and enhanced charge transport. By fabricating organic solar cells (OSCs) with the common acceptor Y6, the PM6-O5:Y6-based device achieved a much higher PCE of 17.65% than that of the reference PM6:Y6-based device. Besides, PM6-O5:Y6-based devices exhibit high thermal- and storage-stability, as well as outstanding photo-stability. This work will provide valuable clues on the molecular design of high-efficiency polymer donors via D-A non-equivalent random copolymerization strategy by incorporating a simple D1 component.

Monodisperse Styrene-Maleic Anhydride-Isoprene Terpolymer Microspheres with Tunable Crosslinking Density Prepared by Self-Stabilized Precipitation Polymerization

Synthesis and industrial production of functional monodisperse microspheres still face enormous challenges like precise size control and process simplification. Herein, a strategy to prepare monodisperse styrene-maleic anhydride-isoprene terpolymer microspheres via self-stabilized precipitation polymerization was reported. The prepared microspheres with different isoprene proportions have uniform particle sizes (623–1156 nm) and narrow size distributions. The structure analysis showed that the copolymerization proceeded in an alternating way between the electron donor (styrene and isoprene) and electron acceptor (maleic anhydride) monomer, and isoprene was incorporated into the polymer chain through 1, 4 addition. The gel fraction of microspheres varies from 0 to 99% along with an increasing isoprene feeding ratio. The Diels–Alder (D–A) reaction between maleic anhydride and isoprene can be effectively inhibited by increasing the amount of initiator or decreasing the polymerization temperature. The resultant uniform microspheres contain reactive anhydride groups and unsaturated C═C bonds derived from isoprene, which can be used to covalently attach functional moieties and have great potential in fields of adsorption and separation, drug delivery, biodetection, and enzyme immobilization.

Fluorine-substituted indolo-thiadiazoloquinoxaline-based D-A type polymers for photovoltaic applications

Two D-A type conjugated polymers, in which the electron-donating benzodithiophene monomers are connected to the electron-accepting indolo-thiadiazoloquinoxaline (ITQ) monomers via a thiophene bridge, are synthesized under Stille coupling conditions. Once the reference PB-ITQ is prepared, one fluorine atom is incorporated into the ITQ unit of PB-ITQ to afford the additional target polymer PB-ITQF. An inverted-type device with the configuration of indium tin oxide (ITO)/ZnO/Polymer:PC71BM/MoO3/Ag is utilized to examine the photovoltaic properties of the two polymers. Owing to the positive contributions of fluorine atoms, all the photovoltaic parameters of the device based on PB-ITQF such as the short-circuit current density, open-circuit voltage, and fill factor are improved as compared with those of the device based on PB-ITQ. As a result, the highest PCE of 2.32% is achieved from the fullerene-based polymer solar cell based on PB-ITQF.

A new building block with intramolecular D-A character for conjugated polymers: ladder structure based on B←N unit

The general strategy to construct D-A type conjugated polymers is alternating copolymerization of electron-donating (D) monomer and electron-accepting (A) monomer. In this article, we report a new strategy to develop D-A type conjugated polymers, i.e. first fuse the D and A units into a polycyclic structure to produce a building block and then polymerize the building block with another unit. We develop a new building block with ladder structure based on B←N unit, B←N bridged dipyridylbenzene (BNDPB). In the skeleton of BNDPB, one diamine-substituted phenylene ring (D unit) and two B←N-linked pyridyl rings (A unit) are fused together to produce the polycyclic structure. Owning to the presence of intramolecular D-A character, the building block itself exhibits narrow bandgap of 1.74 eV. The conjugated polymers based on BNDPB show unique electronic structures, i.e. localized HOMOs and delocalized LUMOs, which are rarely observed for conventional D-A conjugated polymers. The polymers exhibit smaller bandgap than that of the building block BNDPB and display near-infrared (NIR) light absorption ( λ abs=ca. 700 nm). This study thus provides not only a new strategy to design D-A conjugated polymers but also a new kind of building block with narrow bandgap.

Synthesis of novel conjugated polymers based on benzo[1,2-d:4,5-d′]-bis([1,2,3]triazole) for applications in organic field-effect transistors

New conjugated polymers based on 4,8-bis(5-bromothiophen-2-yl)-2,6-bis(2-octyldodecyl)-2H-benzo[1,2-d:4,5-d′]- bis([1,2,3]triazole)-6-ium-5-ide (BTBBTa) displayed the highest hole mobility of 0.21 cm2 V−1 s−1.

New conjugated regular terpolymers based on diketopyrrolopyrrole-benzodithiophene and their application to thin film transistors and polymer solar cells

Conjugated binary copolymers containing an electron donor (D) and acceptor (A) in the repeating unit have been extensively studied due to their excellent charge transport properties. Moreover, conjugated terpolymers containing a third monomer in addition to the two D and A monomers have been recognized to exhibit finely tuned properties relative to the binary D-A copolymer. Diketopyrrolopyrrole (DPP)–based conjugated regular terpolymers (CRTs) containing two different electron donor monomers were synthesized herein to exploit the advantages of the terpolymer. Two terpolymers were synthesized by using bithiophene and pyrene as third monomers. Compared to the reference copolymer, poly[3-(5-(benzo[1,2-b:4,5-b']dithiophen-2-yl)thiophen-2-yl)-2,5-bis(2-decyltetradecyl)-6-(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione] (PDPPBDT), the new terpolymers exhibited distinct physical properties, absorption properties, and electronic energy levels. The terpolymers were employed in thin film transistors (TFTs) and polymer solar cells (PSCs) and the device performance was studied. The highest mobility achieved for the TFT devices was close to 1.0 cm2 V−1 s−1 and was obtained with the PDPPBTBDT terpolymer film as the active layer, whereas the mobilities of the TFTs employing the PDPPPYBDT and PDPPBDT polymers were relatively low. In contrast with the TFT device results, the PSC fabricated with PDPPPYBDT:PC71BM showed the highest power conversion efficiency (PCE) of 4.46% due to the relatively high Voc and Jsc. The results of this study confirmed that the use of a regular terpolymer structure permits fine adjustment of the light absorption range, the molecular energy levels, and the film morphology of the polymer, in turn influencing the device performance of TFTs or PSCs.

Synthesis and electrochemical investigation of beta-substituted thiophene-based donor–acceptor copolymers with 3,4-ethylenedioxythiophene (EDOT)

The present work reports the synthesis of four electron-acceptor beta-substituted thiophenes that were studied as monomers for electrochemical polymerization with 3,4-ethylenedioxythiophene (EDOT), an electron-donating monomer, aiming the combination of electron-acceptor and donor monomer thiophene to a simpler and convenient build up of novel donor–acceptor copolymeric materials via electrochemical polymerization. Four novel copolymers poly(EDOT-co-3-thiophene phenylacetate), (PEDOT-co-PPhTAc-2a), poly(EDOT-co-3-thiophene(4-nitrophenyl)acetate) (PEDOT-co-PPhTAc-2b), poly(EDOT-co-3-thiophenephenylcarboxylate) (PEDOT-co-PPhTCb), and poly(EDOT-co-3-(phenoxymethyl)thiophene) (PEDOT-co-PPhOMT) were electrochemically polymerized. The monomers were characterized by spectrometric techniques (FTIR, 1H NMR, and 13C NMR), and the copolymers were identified by electrochemical analyses and FT-IR. Although the corresponding homopolymers could not be obtained, in the presence of EDOT, the copolymers were formed in a quasi-reversible electrochemical kinetics. The infrared spectra of the copolymers as well the electrochemical profile corroborates their obtaining. The mass variation during the electrosynthesis was analyzed using a quartz crystal microbalance. The film’s morphologies were investigated by SEM. Interestingly, the combination of electron-rich monomer thiophene (EDOT) and these electron-deficient carboxy-substituted thiophenes might be a convenient building block couple to increase the performance control of physic-chemical properties of mixed polythiophenes with innovative applications and they also showed a possible applicability as charge storage device.

Synthesis and characterization of pendant phenyl ester-substituted thiophene based copolymers

In an attempt to synthesize low band gap copolymers, three new monomers 3-ethyl-2-(2,5-dibromothiophene)-3-ylacetate (ETA), 3-phenylethyl-2-(2,5-dibromothiophene)-3-ylacetate (PTA), and 3,3-diphenylpropyl-2-(2,5-dibromothiophene)-3-ylacetate (DPTA) were synthesized. ETA, PTA, and DPTA were copolymerized with 2,5-bis(trimethylstannyl)thiophene to yield poly [3-ethyl 2-(thiophene-3-yl)acetate-2,2′-thiophene] (PETAT), poly[3-phenylethyl 2-(thiophene-3-yl)acetate-2,2′-thiophene] (PPTAT) and poly[3,3-diphenylpropyl 2-(thiophene-3-yl)acetate-2,2′-thiophene] (PDPTAT) respectively. Additionally, these mildly electron-donating monomers as well as 2,5-bis(trimethylstannyl)thiophene were incorporated with the electron withdrawing monomer, 4,7, dibromobenzo[c]-1,2,5-thiadiazole (BT), to develop three push-pull polymeric systems; poly[3-ethyl 2-(thiophene-3-yl)acetate-2,2′-thiophene-2,6-diyl-alt-2,1,3-benzothiadiazole-4,7-diyl] (PETATBT), poly[3-phenylethyl 2-(thiophene-3-yl)acetate-2,2′-thiophene-2,6-diyl-alt-2,1,3-benzothiadiazole-4,7-diyl] (PPTATBT), and poly[3,3-diphenylpropyl 2-(thiophene-3-yl)acetate-2,2′-thiophene-2,6-diyl-alt-2,1,3-benzothiadiazole-4,7-diyl] (PDPTATBT). Copolymers PETAT, PPTAT, and PDPTAT exhibit band gaps from 1.94–1.92eV respectively, where as PETATBT, PPTATBT, and PDPTATBT show a reduction in the band gaps to 1.66–1.48eV. The impact of the phenyl moiety was investigated using atomic force microscopy; increased order within films of PPTAT and PPTATBT can be attributed to the increased π-π stacking in the solid state from the pendant phenyl moiety.

Copolymers with similar comonomers: Tuning frontier orbital energies for application in organic solar cells

Today, there is an intense search for new electron donor polymers for the active layers of organic solar cells. The synthesis of copolymers, in which there is a mix of electron donor monomers with others that are electron acceptors, is a currently employed approach that is used to obtain new polymers with more interesting electronic properties. Usually, the comonomers have a very different structure and the energies of the frontier electronic levels are unpredictable. We demonstrate in this work that the approach of using similar comonomers allows for the provision of copolymers with predictable energies of the frontier electronic levels. We explore the properties of copolymers consisting of monomers of poly(3‐hexylthiophene), poly(3‐hexyloxythiophene) and some poly(3‐hexylthiophene) derivatives. The results indicate that the copolymers have intermediate frontier orbital energies when compared to the parent homopolymers and these energies are easy to predict. This approach is an alternative way of designing a copolymer with favorable tuning of the energies of the frontier electronic levels and is supported by experimental evidence. POLYM. ENG. SCI., 56:479–487, 2016. © 2016 Society of Plastics Engineers

Conjugated polymers based on modified benzo[1,2-b:4,5-b′]dithiophene and perylene diimide derivatives: Good optical properties and tunable electrochemical performance

Three original conjugated polymers were devised and synthesized via the alternating conjugated polymerization of the electron-donating monomer of the modified benzo[1,2-b:4,5-b′]dithiophene (BDT) and electronaccepting monomers of perylene diimide (PDI), dithienyl-perylene diimide (DTPDI) and dithienocoronene diimide (DTCDI), respectively. The synthesized conjugated polymers presented excellent thermal stability (T d >400 °C) as well as broad absorption in visible region and narrow gap of energy level (1.80 to 2.01 eV). Moreover, P(BDT-DTCDI) exhibited strong fluorescence properties (λ em max =736 nm with excitation at 680 nm). According to the theoretical calculations, P(BDT-PDI) and P(BDT-DTPDI) displayed significant polymer backbone torsion (41.44° and 39.64°), and P(BDT-DTCDI) had highly coplanar backbone with negligible angle between BDT and DTCDI. The results indicated that P(BDT-DTCDI) had potential applications in the fields of organic thin-film transistors (OTFTs) and fluorescence materials, and P(BDT-PDI) and P(BDT-DTPDI) could be used as a stable n-type semiconductor for polymer solar cells.

Preparation of slightly crosslinked monodisperse poly(maleic anhydride-cyclohexyl vinyl ether-divinylbenzene) functional microspheres with anhydride groups via precipitation polymerization

Slightly crosslinked monodisperse poly(maleic anhydride-cyclohexyl vinyl ether-divinylbenzene) (MA-CHVE-DVB) microspheres were prepared via precipitation polymerization while using 2,2-azobisisobutyronitrile as an initiator in a mixture of methyl ethyl ketone and n-heptane without any stabilizer. The number-average diameter of the resultant poly(MA-CHVE-DVB) microspheres ranged from 0.478 to 1.386μm with a polydispersity index of 1.00 to 1.02 that depended on the feed ratios of the MA/CHVE/DVB monomers. The introduction of one electron donor monomer cyclohexyl vinyl ether strongly affected the yield, size, and morphology of these slightly crosslinked microspheres. Quinoline-type chelating resins were obtained after combining the poly(MA-CHVE-DVB) with 8-hydroxyquinoline; the adsorption properties of these materials were measured through their ability to remove Cu2+ ions from water. The poly(MA-CHVE-DVB) microspheres with low degrees of crosslinking provided more effective functional groups and therefore better ion removal capabilities. These slightly crosslinked microspheres may have applications in water treatment as well as in sensing and drug delivery.

Synthesis and characterization of organic semiconducting polymers containing dithienylfluorenone for use in organic photovoltaic cells.

2,7-Bis(5-bromo-4-hexylthiophen-2-yl)-9H-fluoren-9-one (DTFO) was synthesized as a new electron-accepting material in semiconducting polymers for use in photovoltaic devices. The synthesized DTFO was polymerized with two different electron-donating counter monomers: 2,7-dibromo-9,9-dioctyl-9H-fluorene (DOF) and 2,6-bis(trimethyltin)-4,8-di(2-ethylhexyloxyl)benzo [1,2-b:4,5-b']dithiophene (BDT). Two alternating copolymers, poly(DTFO-alt-DOF) and poly(DTFO-alt-BDT), were synthesized through the Suzuki and Stille coupling polymerizations, respectively. The synthesized polymers exhibited good solubility in common solvents and show good thermal stability up to 350 °C. The optical band gap energies of poly(DTFO-alt-DOF) and poly(DTFO-alt-BDT) were determined to be 2.44 and 2.23 eV, respectively. The positions of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the polymers were determined by cyclic voltammetry (CV). One of these devices showed a power conversion efficiency of 0.50%, with an open-circuit voltage of 0.67 V, a short-circuit current of 2.34 mA/cm2, and a fill factor of 0.30 under air mass (AM) 1.5 global (1.5 G) illumination conditions (100 mW/cm2).

Synthesis and photovoltaic properties of n-type conjugated polymers alternating 2,7-carbazole and arylene diimides

A series of conjugated polymers were designed and synthesized via the alternating copolymerization of the electron-donating monomer 2,7-carbazole and electron-accepting monomers of naphthalene diimide (NDI), dithienyl-naphthalene diimide (DTNDI), perylene diimide (PDI) and dithienyl-perylene diimide (DTPDI), respectively. The obtained four copolymers showed good thermal stability as well as broad absorptions in visible region and narrow optical band gaps (1.86–1.59eV). Through cyclic voltammetry (CV) measuremnts, it was found that all copolymers were n-type semiconductive materials. The copolymers' photovoltaic properties were evaluated when the blends of poly(3-hexyl thiophene) (P3HT) and copolymers were used as the active layers of polymer solar cells (PSCs): among four copolymers, the copolymer alternating 2,7-carbazole and DTPDI units (PCDTPDI) exhibited the best photovoltaic performance with an open-circuit voltage (Voc) of 0.48V, a short circuit current density (Jsc) of 3.40mA/cm2, fill factor (FF) of 0.42, and a power conversion efficiency (PCE) of 0.68%.

Influence of Strong Electron-Donor Monomers in Sequence-Controlled Polymerizations.

A series of styrenic monomers containing strong donor substituents (i.e., 4-methylstyrene, 4-acetoxystyrene, and 4-tert-butoxystyrene) were tested in sequence-controlled radical copolymerizations in the presence of acceptor comonomers (i.e., N-substituted maleimide). The copolymers were synthesized by nitroxide-mediated polymerization using the commercially available alkoxyamine BlocBuilder MA. This technique allowed synthesis of copolymers with controlled molecular weights and molecular weight distributions for all monomers. Moreover, a beneficial effect of the donor substituents on the sequence-controlled copolymerization was noted. Indeed, all studied styrenic derivatives led to a very precise incorporation of functional N-substituted maleimides in the copolymer chains. The most favorable donor/acceptor copolymerization was observed with 4-tert-butoxystyrene. This particular monomer was therefore tested in the presence of various functional N-substituted maleimides (i.e., N-benzyl maleimide, 4-(N-maleimido) azobenzene), N-(1-pyrenyl)maleimide, and N-(2-(amino-Boc)ethylene)maleimide). In all cases, sequence-controlled microstructures were obtained and characterized. Moreover, the formed copolymers were hydrolyzed into poly(4-hydroxystyrene-co-N-substituted maleimide) derivatives. In all cases, it was verified that the sequence-controlled microstructure of the copolymers is preserved after hydrolysis.

Three new conjugated polymers based on benzo[2,1-b:3,4-b′]dithiophene: synthesis, characterization, photoinduced charge transfer and theoretical calculation studies

Three new conjugated polymers have been designed and synthesized via the alternate copolymerization of the electron-donating monomer benzodithiophene (BDT) and three different electron-accepting monomers: 5,8-dibromoquinoxaline, 5,8-dibromo-2,3-diphenylquinoxaline, 10,13-dibromodibenzo[a,c]phenazine. The synthesized polymers show good solubility in common organic solvents as well as broader absorptions in the visible region and narrower optical band gaps compared to homopolymers made from BDT units. It is found that the absorptions of the copolymers are red-shifted by increasing the electron-withdrawing ability of the co-monomer. In particular, the absorption edge of the P3 film extends to 778 nm, whereas that of the P1 film is only at 636 nm. Theoretical calculation studies of structure–property relations indicated that polymer chains with better coplanarity or π–π* delocalization will lead to lower band gaps. Photoinduced charge transfer (PCT) studies disclosed that exciton dissociation of photoexcited PX (X = 1, 2, 3) via electron-transfer may occur at the interface with CHL-C60, enabling the photogeneration of electrons and holes. The P3/CHL-C60 blended film was chosen as a representative sample to test the applicability of the polymer P3 for energy conversion, a 1.76% PCE was finally obtained.

Synthesis, Kinetics and Mechanism of Terpolymerization of Styrene, Vinyl Acetate with Acrylonitrile Initiated by P-Nitrobenzyl Triphenyl Phosphonium Ylide

Synthesis of terpolymers consisting of two electron-donating monomers, viz. styrene and vinyl acetate with one electron-accepting monomer, i.e. acrylonitrile, initiated by p-nitrobenzyl triphenyl phosphonim ylide in dioxane as diluent at 65°C for 150 min has been studied. The kinetic expression is Rpα[I]0.8[Sty] 1.2[VA] 1.4 [AN]1.2. The terpolymer composition was determined by the Kelen-Tüdos method. The values of reactivity ratios using r1 (Sty + VA) = 0.1 and r2 (AN) = 0.005. The overall activation energy is 46 kJ●mol●L–1. The formation of terpolymer is confirmed by the FTIR spectra showing bands at 3030 cm–1, 1598 cm–1, and 2362 cm–1, confirming the presence of phenyl, acetoxy and nitrile group respectively. The terpolymer has been characterized by 1H-Nuclear Magnetic Resonance, 13C-Nuclear Magnetic Resonance. The Differential Scanning Calorimetric curve shows the Tg of the polymer as 149.5°C. A scanning electron microscope confirms the polymer to be phosphorus free. Electron.Spin.Resonance spectra confirms phenyl radical responsible for initiation.

Conjugated polymers based on benzodithiophene and arylene imides: Extended absorptions and tunable electrochemical properties

Three novel conjugated polymers have been designed and synthesized via the alternative copolymerization of the electron-donating monomer benzodithiophene (BDT) and three different electron-accepting monomers: perylene diimide (PDI), naphthalene diimide (NDI), and phthalimide (PhI). All obtained copolymers show good solubility in common organic solvents as well as broader absorptions in visible region and narrower optical band gaps compared to homopolymers from BDT units. It is found that the absorptions of the copolymers are red-shifted with increasing the electron-withdrawing ability of the co-monomer. In particular, the absorption edge of P(BDT-NDI) film extends to 760 nm, whereas that of P(BDT-PhI) film is only at 577 nm. Cyclic voltammograms of the three polymers disclose that P(BDT-PDI) and P(BDT-NDI) are typical n-type materials because PDI and NDI are strong electron-accepting groups, while P(BDT-PhI) is a stable p-type material where the weak electron-withdrawing monomer (PhI) is introduced. The results suggest that the absorption range and the electrochemical properties of the conjugated polymers can be tuned by appropriate molecule-tailoring, which will help exploring ideal conducting polymers for potential applications in polymer optoelectronics, especially in polymer solar cells.

Molecular-shape selectivity tuned by donor–acceptor type copolymers as organic phase in reversed-phase high-performance liquid chromatography

The copolymer with a terminal reactive group (copoly-VP 17 MA 12 ) was newly designed and prepared by selecting 4-vinylpyridine (VP) as an electron-donating monomer and methyl acrylate (MA) as an electron-accepting monomer. Copoly-VP 17 MA 12 was grafted onto porous silica particles by a silanol coupling reaction with the terminal group. Individually, poly-VP 15 and poly-MA 20 with a terminal reactive group were also synthesized and co-grafted onto silica (Sil-cograft-VP 15 MA 20 ) to compare the effect of the copolymer-grafted (Sil-copoly-VP 17 MA 12 ) and polymer co-grafted stationary phases in HPLC separation. All the polymers were characterized by 1H NMR and FT-IR analysis before grafting on silica. Polymer grafting was confirmed by diffuse reflectance infrared Fourier transform (DRIFT), elemental analysis and thermogravimetric analysis (TGA). The intra- and intermolecular interaction between monomer units in copolymer-grafted and polymer co-grafted systems, respectively was observed by DRIFT measurement. The detailed chromatographic study revealed using PAHs as solutes that remarkably higher selectivity for planar/non-planar discrimination was observed with the copolymer-grafted phase than with the co-grafted stationary phase. In this paper, it is also discussed that the selectivity enhancement by copolymer-grafting in the Sil-copoly-VP 17 MA 12 phase can be brought through intramolecular interaction between VP and MA.

UV curing of a novel resin derived from poly(ethylene terephthalate)

AbstractThe synthesis and characterization of photopolymerizable unsaturated polyester resins based on PET waste are described. The resins came from a depolymerization process based on the glycolysis of PET by diethylene glycol (DEG). Different molecular weights of glycolysates were synthesized. Then, the latter was functionalized by a methyl hemiester of maleic acid to obtain unsatured α,ω‐bismaleate PET oligomers. In the presence of an electron donor monomer, such as triethylene glycol divinyl ether, these electron acceptor oligomers were copolymerized by way of charge‐transfer complexes under UV irradiation. The reaction was monitored in situ by real‐time IR spectroscopy to study the kinetics of photopolymerization. This one was studied in relation with the physical and chemical characteristics of oligoesters and the composition of mixtures containing divinyl ethers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1324–1335, 2007