Co-reporter:Lucas Caire da Silva, Giovanni Rojas, Michael D. Schulz, Kenneth B. Wagener
Progress in Polymer Science 2017 Volume 69(Volume 69) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.progpolymsci.2016.12.001
Acyclic Diene Metathesis (ADMET) polymerization was established decades ago and has since developed into a robust and reliable technique. A wide range of different, new materials exhibiting unique properties has been produced via ADMET polymerization since its development. This versatile technique allows, through the right combination of monomer design and choice of catalyst, the synthesis of various functional polymers in addition to a precise control over primary structure. Systematic studies on precise ADMET polymers have greatly contributed to a better understanding of how branch identity and its distribution along the polymer backbone affect the thermal/electronic properties, crystallization, molecular dynamics and morphology of different materials. This article presents an extensive review of how ADMET started, the mechanism that underlies the structural features of ADMET polymers and the different strategies and techniques that have been developed over the years to overcome common synthetic challenges. Monomer synthesis methods are also discussed in detail, providing an important overview of the limitations and advantages of using ADMET as a polymerization technique. Many examples are given of functional ADMET polymers that have been developed by research groups all over the world.
Co-reporter:Nicolas F. Sauty, Lucas Caire da Silva, Caitlyn Gallagher, Robert Graf and Kenneth B. Wagener
Polymer Chemistry 2016 vol. 7(Issue 2) pp:502-502
Publication Date(Web):08 Dec 2015
DOI:10.1039/C5PY90201K
Correction for ‘Unveiling the hyperbolic thermal behaviour of poly(p-phenylene alkylene)s’ by Nicolas F. Sauty et al., Polym. Chem., 2015, 6, 6073–6082.
Co-reporter:Patricia R. Bachler, Kaitlyn E. Forry, Chelsea A. Sparks, Michael D. Schulz, Kenneth B. Wagener and Brent S. Sumerlin
Polymer Chemistry 2016 vol. 7(Issue 25) pp:4155-4159
Publication Date(Web):06 Jun 2016
DOI:10.1039/C6PY00819D
Modular segmented hyperbranched polymers, amenable to facile post-polymerization functionalization, were created via two distinct approaches. Self-condensing vinyl polymerization via reversible addition–fragmentation chain transfer (RAFT) polymerization and RAFT polymerization with a divinyl comonomer were employed to create well-defined highly branched materials containing activated esters amenable to highly efficient functionalization in a modular manner.
Co-reporter:Lucas Caire da Silva;Clifford R. Bowers;Robert Graf
Macromolecular Rapid Communications 2016 Volume 37( Issue 6) pp:527-531
Publication Date(Web):
DOI:10.1002/marc.201500642
Co-reporter:Lucas Caire da Silva
Macromolecular Chemistry and Physics 2016 Volume 217( Issue 7) pp:850-855
Publication Date(Web):
DOI:10.1002/macp.201500508
Co-reporter:Nicolas F. Sauty, Lucas Caire da Silva, Caitlyn Gallagher, Robert Graf and Kenneth B. Wagener
Polymer Chemistry 2015 vol. 6(Issue 33) pp:6073-6082
Publication Date(Web):08 Jul 2015
DOI:10.1039/C5PY00625B
A series of poly(p-phenylene alkylene)s with methylene run lengths ranging from 8 to 40 were obtained by ADMET polymerization of symmetrical α,ω-diene monomers and subsequent exhaustive hydrogenation. ADMET polymerizations were conducted using dibenzyl carbonate as solvent for the first time, providing materials with high molecular weights as compared with those obtained in standard solvent-free conditions. The thermal properties of both the unsaturated and saturated series were investigated. Poly(p-phenylene alkylene)s exhibit an unprecedented thermal behaviour when considering the fusion temperature as a function of the number of methylene spacers. Solid state 1H MAS and 1H–13C correlation experiments demonstrated that the melting behavior is marked by the gradual disruption of the ring π–π interactions with increasing methylene chain length. The higher crystallization tendency of longer alkyl chains was detected by the characteristic broadening of the corresponding solid-state 1H NMR signals and explains the observed increase in melting temperature with the methylene chain length.
Co-reporter:Taylor W. Gaines, Tatsuya Nakano, Yoshiki Chujo, Edward B. Trigg, Karen I. Winey, and Kenneth B. Wagener
ACS Macro Letters 2015 Volume 4(Issue 6) pp:624
Publication Date(Web):May 20, 2015
DOI:10.1021/acsmacrolett.5b00258
Copolymers containing sulfite functionalities precisely placed between run lengths of 8, 14, and 20 methylene units were synthesized via ADMET with weight-average molecular weights up to 40 500 g/mol (PDI = 1.89). No such polymer structures have been observed previously. The primary polymer structures and precise nature were characterized by 1H NMR, 13C NMR, and IR spectroscopy. Thermal degradation temperatures up to 310 °C were observed through TGA, and melting points typical of similar unsaturated ADMET polymers were determined by DSC. X-ray scattering was used to compare the polymers to ADMET polyethylene (PE), and when the polymers have 20 carbons between sulfites, the functional groups self-assemble into layers. Higher carbon content incorporation leads to an increase in crystallinity and thermal stability for these polysulfites.
Co-reporter:Hong Li, Giovanni Rojas, and Kenneth B. Wagener
ACS Macro Letters 2015 Volume 4(Issue 11) pp:1225
Publication Date(Web):October 21, 2015
DOI:10.1021/acsmacrolett.5b00641
A series of polyethylenes containing 21-carbon alkyl branches have been synthesized by acyclic diene metathesis (ADMET) polymerization. These 21-carbon alkyl branches are precisely placed on every 15th, 19th, 21st, 23rd, and 39th carbon along the polymer backbone. Precision of primary structures of all polymers is verified by 1H and 13C NMR spectroscopy. All polymers present well-defined melting profiles, even at a high branch incorporation (13.3% mol). The melting temperature increases as the branch frequency decreases, similar to what we observed for short-chain branched polyethylenes. These observations together with a good linear relationship derived from Flory’s theory suggest the exclusion of 21-carbon side chains from polyethylene crystal units.
Co-reporter:Patricia R. Bachler;Michael D. Schulz;Chelsea A. Sparks;Brent S. Sumerlin
Macromolecular Rapid Communications 2015 Volume 36( Issue 9) pp:828-833
Publication Date(Web):
DOI:10.1002/marc.201500060
Co-reporter:Donovan L. Thompson;Ulrich Schulze;Brigitte Voit;Dieter Jehnichen;Mikhail Malanin
Macromolecular Rapid Communications 2015 Volume 36( Issue 1) pp:60-64
Publication Date(Web):
DOI:10.1002/marc.201400545
Co-reporter:Taylor W. Gaines, Kathryn R. Williams, Kenneth B. Wagener, Giovanni Rojas
Tetrahedron Letters 2015 Volume 56(Issue 25) pp:3923-3927
Publication Date(Web):17 June 2015
DOI:10.1016/j.tetlet.2015.04.122
Microwave-assisted ADMET polymerization is reported on a series of α,ω-diene monomers, both polar and non-polar. Investigations indicate that of the multiple microwave modes possible, constant power is the most advantageous, providing polymers up to M‾w = 31,000 g/mol. Molecular weight values are nearly triple in comparison with conventional oil bath heating. Polymers are characterized by NMR, GPC, TGA, and DSC. Microwave irradiation provides a highly controllable and energy efficient ADMET polymerization technique.
Co-reporter:Chester Simocko, Thomas C. Young, and Kenneth B. Wagener
Macromolecules 2015 Volume 48(Issue 16) pp:5470-5473
Publication Date(Web):August 12, 2015
DOI:10.1021/acs.macromol.5b01410
Precise aryl boronic ester- and acid-containing polymers have been synthesized via acyclic diene metathesis. High-molecular weight phenyl boronic acid polymers were synthesized. Cross-linked phenyl boronic acid polymers were also synthesized and demonstrate a unique crystallization behavior not usually seen in cross-linked polymers.
Co-reporter:Lucas Caire da Silva, Robert Graf, Clifford R. Bowers, and Kenneth B. Wagener
Macromolecules 2015 Volume 48(Issue 24) pp:8858-8866
Publication Date(Web):December 4, 2015
DOI:10.1021/acs.macromol.5b01882
The effect of branching on the chain dynamics of model branched polyethylene was studied by solid state 2H and 13C NMR. Methyl branched polyethylene models with branches at every 15th (PE15) and 21st (PE21) chain carbon were synthesized with deuterons placed either at the carbon alpha to the branching point or in the middle of the chain between branches. Line shape analysis of the temperature-dependent 2H spectra revealed that the distribution of motional amplitudes in the solid state is homogeneous along the crystalline chain but heterogeneous in the less constrained amorphous phase. The 13C and 2H longitudinal spin relaxation data obtained at different positions along the chain are explained in terms of the segmental dynamics as a function of branch incorporation into the crystals. A detailed analysis of the chain dynamics in the conformationally disordered phase exhibited in PE15 is also provided.
Co-reporter:Patricia R. Bachler
Monatshefte für Chemie - Chemical Monthly 2015 Volume 146( Issue 7) pp:1053-1061
Publication Date(Web):2015 July
DOI:10.1007/s00706-015-1479-7
Acyclic diene metathesis (ADMET) polymerization is a powerful and versatile technique for creating precision polymers. Specialized and well-defined materials, as well as improved understanding of structure–property relationships, can be achieved by ADMET polymerization of designed symmetrical monomer structures. The introduction of functional groups into ADMET polymers, from polar groups to biodegradable moieties, has resulted in an array of precision functional materials with distinct properties and interesting applications.
Co-reporter:Michael D. Schulz;Nicolas F. Sauty
Applied Petrochemical Research 2015 Volume 5( Issue 1) pp:3-8
Publication Date(Web):2015 March
DOI:10.1007/s13203-013-0041-y
Herein, we review the major advances in controlling polyethylene morphology through precise control of branch frequency and identity. This control is made possible by the acyclic diene metathesis reaction.
Co-reporter:Chip S. Few;Donovan L. Thompson
Macromolecular Rapid Communications 2014 Volume 35( Issue 2) pp:123-132
Publication Date(Web):
DOI:10.1002/marc.201300672
Co-reporter:Michael D. Schulz
Macromolecular Chemistry and Physics 2014 Volume 215( Issue 20) pp:1936-1945
Publication Date(Web):
DOI:10.1002/macp.201400268
Co-reporter:Donovan Thompson;Ryohei Yamakado
Macromolecular Chemistry and Physics 2014 Volume 215( Issue 12) pp:1212-1217
Publication Date(Web):
DOI:10.1002/macp.201400117
Co-reporter:Chip S. Few, Kathryn R. Williams, Kenneth B. Wagener
Tetrahedron Letters 2014 Volume 55(Issue 32) pp:4452-4454
Publication Date(Web):6 August 2014
DOI:10.1016/j.tetlet.2014.06.055
We find that Magtrieve™ (CrO2) catalyzes the oxidation of a wide variety of alcohols with periodic acid as the terminal oxidant. Mild conditions, short reaction times, and facile aqueous work-up make this a most attractive method. Olefins are not oxidized under these conditions; thus alcohols react selectively in the presence of alkenes. Conditions have been optimized with respect to catalyst loading, solvent, and co-oxidant; and the scope of the reaction includes primary and secondary benzylic, allylic, and aliphatic alcohols.We find that Magtrieve™ (CrO2) catalyzes the oxidation of a wide variety of alcohols with periodic acid as the terminal oxidant. Mild conditions, short reaction times, and facile aqueous work-up make this a most attractive method. Olefins are not oxidized under these conditions; thus alcohols react selectively in the presence of alkenes. Conditions have been optimized with respect to catalyst loading, solvent, and co-oxidant; and the scope of the reaction includes primary and secondary benzylic, allylic, and aliphatic alcohols.
Co-reporter:Nicolas F. Sauty;Lucas Caire da Silva;Michael D. Schulz
Applied Petrochemical Research 2014 Volume 4( Issue 2) pp:225-233
Publication Date(Web):2014 June
DOI:10.1007/s13203-014-0045-2
The history of and major advances in the acyclic diene metathesis (ADMET) reaction are described. Because precise branch identity and frequency can be achieved by ADMET polymerizations of symmetrical α,ω-dienes, polyethylenes with precisely spaced alkyl branches of specified length have been prepared. Investigations of their morphologies and thermal properties have provided valuable insight into the behavior of polyethylene. ADMET preparation of ethylene copolymers and telechelic oligomers, as well as the properties of these materials, is also discussed.
Co-reporter:Chester Simocko, Yong Yang, Timothy M. Swager, and Kenneth B. Wagener
ACS Macro Letters 2013 Volume 2(Issue 12) pp:1061
Publication Date(Web):November 20, 2013
DOI:10.1021/mz4004776
Metathesis step-growth polymerizations in ionic liquids (ILs) was explored to take advantage of the high boiling points of ILs, thereby permitting the use of low pressures at high temperatures. Optimization reactions found that high polymers form efficiently using small amounts of catalyst and short reaction times. For example, high molecular weight main-chain triptycene polymers with high triptycene incorporation were synthesized. This new methodology is applicable to various metathesis reactions that require removal of volatile byproducts as a driving force, including acyclic diene metathesis (ADMET).
Co-reporter:Michael D. Schulz, Rachel R. Ford and Kenneth B. Wagener
Polymer Chemistry 2013 vol. 4(Issue 13) pp:3656-3658
Publication Date(Web):22 May 2013
DOI:10.1039/C3PY00531C
We have successfully depolymerized polybutadiene via an insertion metathesis mechanism. This new concept involves the irreversible depolymerization of unsaturated polymers with electron deficient olefins. The product of the degradation was characterized by NMR and GC-MS. We also explored the use of copper iodide as an additive. We observed significant reduction of molecular weight under a variety of conditions with the most extensive depolymerization occurring with the use of Grubbs 2nd generation catalyst with CuI. Finally, polybutadiene was converted to a polyamide by performing insertion metathesis depolymerization with acryloyl chloride and subsequently reacting with 1,6-diaminohexane, demonstrating the potential of polymer-to-polymer conversions with this chemistry.
Co-reporter:Pascale Atallah, Kenneth B. Wagener, and Michael D. Schulz
Macromolecules 2013 Volume 46(Issue 12) pp:4735-4741
Publication Date(Web):May 21, 2013
DOI:10.1021/ma400067b
Olefin metathesis has been embraced by polymer chemists as a method for creating well-defined polymers. In particular, ADMET and ROMP have emerged as the primary modes of metathesis polymerization. ADMET reactions are now common, found in textbooks, and easy to perform if the proper techniques are chosen. Much remains to be done, however, with work now focusing on silicon chemistry, direct control of tacticity in precision polymers, biological applications, modeling crystal lattices in common polyolefins, exploring solid-state metathesis reactions, and creating water-soluble ADMET polymers.
Co-reporter:Chester Simocko and Kenneth B. Wagener
Organometallics 2013 Volume 32(Issue 9) pp:2513-2516
Publication Date(Web):April 29, 2013
DOI:10.1021/om400257b
Boron-containing Lewis acids have shown a profound effect on the cross-metathesis reaction of 1-hexene. Grubbs first-generation catalyst shows over 100% improvement in conversion in some cases, while the yields increase by up to 50% with Grubbs second-generation catalyst. With the inclusion of boron-containing Lewis acids, compounds prepared using Grubbs second-generation-type catalysts display significantly reduced levels of isomerization.
Co-reporter:Kazuya Matsui, Shuichiro Seno, Yoshinobu Nozue, Yuya Shinohara, Yoshiyuki Amemiya, E. B. Berda, G. Rojas, and K. B. Wagener
Macromolecules 2013 Volume 46(Issue 11) pp:4438-4446
Publication Date(Web):May 21, 2013
DOI:10.1021/ma400608q
Depending on the degree of short chain branch (SCB) incorporation, the crystallization behavior and resultant crystalline structure drastically change in polyethylene with precisely spaced branches. In polyethylene with hexyl branches precisely spaced on every 21st carbon (HB21), only crystallization mediated by a transient hexagonal phase without incorporation of the SCB was observed. On the other hand, in polyethylene with ethyl branches precisely spaced on every 21st carbon (EB21), crystallization behavior was strongly dependent on the crystallization temperature. A thin lamella was formed through crystallization mediated by a hexagonal phase and no thickening occurred at 5–8 °C, while thickening of the transient hexagonal lamellae occurred at 10–15 °C, and one SCB seemed to be incorporated into a crystal stem. At 17 °C, no thickening of the hexagonal phase occurred and a hexagonal phase with sufficient lamella thickness was directly formed from the melt. At 21–28 °C, crystallization mediated by hexagonal phase formation was not clearly observed and the crystalline phase was mainly formed by nucleation and growth of a spherulite. Transition between crystallization mediated by a hexagonal phase and that by nucleation and growth of a spherulite is dominated by the degree of SCB incorporation into the crystalline lamellae. At 21 °C or higher, the inclusion of two branches into a stem destabilizes the hexagonal structure, while the free energy of formation of a triclinic phase may be stabilized by tilting the chains and optimizing the packing of the SCB inside the crystal.
Co-reporter:Brian S. Aitken, Patrick M. Wieruszewski, Kenneth R. Graham, John R. Reynolds, and Kenneth B. Wagener
ACS Macro Letters 2012 Volume 1(Issue 2) pp:324
Publication Date(Web):February 3, 2012
DOI:10.1021/mz2001725
A set of six perfectly regioregular pendant 2,7-bis(phenyl-m-toluylamino)fluorene (TPF) functionalized polyolefins for use as charge transporting materials in polymer light emitting diodes (PLEDs) were prepared and characterized. Synthesis of these materials is straightforward, requiring only three or four steps, depending on the polymer, and final isolated yields over all steps combined were greater than 40% in all but one case. Most notably, these materials exhibit charge-carrier mobilities that can be controlled over 3 orders of magnitude by variation of the number of intermediary carbons (spacer length) between the pendant TPF groups. The range of hole mobilities encompasses the electron mobilities of common electron transport materials/emitters such as Alq3 and PBD, thus, affording the opportunity to fabricate electroactive polyolefin based PLEDs with well matched charge-carrier mobilities and improved performance. We believe this approach to charge-carrier mobility control in electroactive materials could be easily extended to other aryl systems with different HOMO–LUMO levels for energy level and mobility matching with various emitters.
Co-reporter:Yoshinobu Nozue, Shuichiro Seno, Tatsuhiro Nagamatsu, Satoru Hosoda, Yuya Shinohara, Yoshiyuki Amemiya, E. B. Berda, G. Rojas, and K. B. Wagener
ACS Macro Letters 2012 Volume 1(Issue 6) pp:772
Publication Date(Web):June 8, 2012
DOI:10.1021/mz300215u
In cross nucleation, an early nucleating crystalline polymorph (A) nucleates another crystalline polymorph (B) of higher or lower thermodynamic stability without undergoing a polymorphic transformation. Although this phenomenon was recently observed in the crystallization process of several small molecules, there has been insufficient evidence for cross nucleation in a crystalline polymer. In this paper, we report cross nucleation behavior during an isothermal crystallization of a crystalline polymer with precisely spaced branches. Polyethylene with ethyl branches on every 21st carbon exhibited growth of new spherulites at the growth front of an initially formed spherulite. The radial growth rate of the initially formed spherulite and the newly grown spherulite calculated from polarized optical microscope data were 0.76 μm/min and 1.01 μm/min, respectively. The growth rate of the newly grown spherulite is faster than that of the initially formed spherulite, which meets a required condition for cross nucleation. Scanning microbeam wide-angle X-ray scattering (WAXS) confirmed that the crystalline polymorphs of the two kinds of spherulites are not the same.
Co-reporter:Michael D. Schulz and Kenneth B. Wagener
ACS Macro Letters 2012 Volume 1(Issue 4) pp:449
Publication Date(Web):March 13, 2012
DOI:10.1021/mz200236r
Alternating AB copolymers were synthesized by exploiting the selectivity of the metathesis reaction between α,ω-dienes and α,ω-diacrylates. Unlike standard acyclic diene metathesis (ADMET) polymerizations, the copolymerization of dienes and diacrylates does not require high vacuum conditions. This work utilizes this unique characteristic to explore the effect of various solvents on ADMET polymerization. We found significant variation in the efficacy of the solvents we screened, with CH2Cl2 yielding the highest molecular weight polymer. Additionally, the performance of Grubbs second generation catalyst was compared with Hoveyda–Grubbs second generation catalyst in different solvents, revealing a stark difference in the molecular weight of the resulting polymers in CH2Cl2 but a relatively minor difference in the final molecular weight from polymerizations in acetic acid.
Co-reporter:Brian S. Aitken, Patrick M. Wieruszewski, Kenneth R. Graham, John R. Reynolds, and Kenneth B. Wagener
Macromolecules 2012 Volume 45(Issue 2) pp:705-712
Publication Date(Web):January 6, 2012
DOI:10.1021/ma202409k
Acyclic diene metathesis polymerization (ADMET) was used to synthesize a series of perfectly regioregular polyolefins, in which the number of backbone atoms between pendant terfluorene groups was precisely controlled at 8, 14, or 20 carbons. Analogous random copolymers containing identical chromophore densities were also synthesized to study the impact of regioregularity on the performance of this class of materials in polymer light emitting diodes (PLEDs). Additionally, the backbone alkene remnants of ADMET were saturated to generate materials with somewhat different ordering. These saturated derivatives led to improvements in PLED external quantum efficiencies (EQEs) over their unsaturated analogues in most cases, with a large improvement in one material. Charge mobility, as manifested in current density during PLED characterization, and relative solid-state fluorescence quantum yield (ΦF) also exhibit reasonable dependencies, with longer distances between electroactive groups yielding lower PLED current densities and higher ΦF. Regioregularity has the opposite effect, giving rise to higher current densities and lower ΦF as compared to regiorandom analogues.
Co-reporter:Brian S. Aitken, C. Francisco Buitrago, Jason D. Heffley, Minjae Lee, Harry W. Gibson, Karen I. Winey, and Kenneth B. Wagener
Macromolecules 2012 Volume 45(Issue 2) pp:681-687
Publication Date(Web):January 6, 2012
DOI:10.1021/ma202304s
Six perfectly regioregular polyethylene (PE)-based ionomers containing 1-methylimidazolium bromide groups on exactly every 9th, 15th, or 21st carbon (precision ionomers) and two regiorandom analogues have been synthesized and characterized via dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Because these materials were synthesized by a postpolymerization functionalization route, their number-average molecular weights (Mns) and polydispersity indices (PDIs) could be accurately calculated based on measurements of the preionized polymers; Mns range from 36 to 53 kDa with PDIs all close to 2. Thermal gravimetric analysis (TGA) indicates stability up 250 °C, and DSC measurements indicate that crystallinity is a function of the polymer backbone spacer length. Tms range from ∼80 to 106 °C, with longer spacer lengths inducing semicrystallinity. DSC measured glass transition temperatures (Tgs) range from −1.6 to 26.8 °C and appear to be dependent on both spacer length and crystallinity. DMA data loosely mirror the DSC results, but with transitions occurring at lower temperatures that we attribute to differences in the thermal history and/or the different heating ramp rates used.
Co-reporter:Bora Inci, Ingo Lieberwirth, Werner Steffen, Markus Mezger, Robert Graf, Katharina Landfester, and Kenneth B. Wagener
Macromolecules 2012 Volume 45(Issue 8) pp:3367-3376
Publication Date(Web):April 15, 2012
DOI:10.1021/ma3002577
Synthesis and morphological characterization are reported for a series of 13 precision branched polyethylene structures, the branch being placed on every 39th carbon and varying in size from methyl to pentadecyl group. A recently established synthetic scheme for preparation of the symmetrical α,ω-diene monomer was employed to increase the number of methylene carbons between the branch points from 20 to 38, yielding polymers with 5.26 mol % α-olefin incorporation. The morphology of these polymers was investigated using differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and transmission electron microscopy (TEM). Methyl branching significantly reduces the melting point and single crystal lamellae thickness of unbranched polyethylene. On the other hand, all further branches from ethyl to pentadecyl produce polymers that have similar melting points and single crystal lamellae thicknesses. A clear change in the morphology of both solution and melt-grown crystals of these polymers was observed from a situation where the methyl branch is incorporated in the polymer′s unit cell to one where branches of greater mass are mostly expelled from the unit cell.
Co-reporter:James K. Leonard, Yuying Wei, and Kenneth B. Wagener
Macromolecules 2012 Volume 45(Issue 2) pp:671-680
Publication Date(Web):December 19, 2011
DOI:10.1021/ma202233a
A structural investigation of linear ethylene-co-vinyl amine (EVAm) copolymers having a primary amine branch on every 9th, 15th, 19th, or 21st carbon along the ethylene backbone has been completed using step polymerization chemistry. Acyclic diene metathesis (ADMET) polymerization has been used with symmetrical α,ω dienes containing protected amine groups to afford polymers with exact primary structures and constant methylene run lengths between branches. The effects of subtle structural changes such as the ethylene run lengths between amine branches can be observed and used to correlate structure property relationships. NMR and FT-IR techniques are used to characterize and verify the excellent structural control this synthetic approach provides over traditional chain polymerization techniques. Thermal decomposition of these copolymers is shown to additionally support polymer structure while differential scanning calorimetry demonstrates crystallinity in the polymers with an amine on every 15th and 21st carbon, whereas the polymer with an amine on every ninth carbon is amorphous. Variations of the physical and spectral properties are discussed as a consequence of the amine branch spacing, protection, and saturation of the ethylene backbone.
Co-reporter:Paula A. Delgado;Piotr Matloka;Fabio Zuluaga
Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 3) pp:431-440
Publication Date(Web):
DOI:10.1002/pola.25048
Abstract
Acyclic diene metathesis (ADMET) polymerization has been used in the synthesis of telechelic materials using alkoxy-functionalized carbosiloxane or oligo(oxyethylene)-based polymers, varying from internal to terminal cured materials or the combination of them. Previous investigations demonstrated that introduction of chain-end crosslinking improves the stress–strain behavior of such materials. A series of saturated and unsaturated carbosiloxane and oligo(oxyethylene)-based polymers were synthesized by ADMET polymerization using silacyclobutane as chain-end, thermally induced crosslinker. The carbosiloxane derivatives presented pure amorphous behavior, whereas the oligo(oxyethylene) polymers were semicrystalline. The thermal curing process was monitored by differential scanning calorimetry via the exotherm between 160 and 210 °C. Mechanical properties on thermoset polymers were measured, where cured polymers showed moduli from 0.6 to 9.3 MPa, tensile strengths from 0.3 to 1.0 MPa, and elongations from 12 to 76%. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Co-reporter:Bora Inci
Journal of the American Chemical Society 2011 Volume 133(Issue 31) pp:11872-11875
Publication Date(Web):July 19, 2011
DOI:10.1021/ja2040046
A symmetrical α,ω-diene monomer with a 36 methylene run length was synthesized and polymerized, and the unsaturated polymer was hydrogenated to generate precision polyethylene possessing a butyl branch on every 75th carbon (74 methylenes between branch points). The precision polymer sharply melts at 104 °C and exhibits the typical orthorhombic unit cell structure with two characteristic wide-angle X-ray diffraction (WAXD) crystalline peaks observed at 21.5° and 24.0°, corresponding to reflection planes (110) and (200), respectively.
Co-reporter:Kathleen L. Opper
Journal of Polymer Science Part A: Polymer Chemistry 2011 Volume 49( Issue 4) pp:821-831
Publication Date(Web):
DOI:10.1002/pola.24491
Abstract
Although it is well known that Acyclic Diene METathesis (ADMET) describes an olefin metathesis polymerization mode that relies on double-bond substituent interchange of a diolefin, the story behind its discovery is not. The story is divulged here. Olefin metathesis has a rich history dating to the 1950s, but the one particular metathesis mode mentioned, ADMET, has more recent historical roots. ADMET polymerization is easy to do and highlighted here are the particular reaction details for success. Additionally, the most recent advances from the past 5 years are detailed, exemplifying this reaction's wide utility from fundamental structure–property studies to multiple advanced applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Co-reporter:Satoru Hosoda, Yoshinobu Nozue, Yasutoyo Kawashima, Kouei Suita, Shuichiro Seno, and Tatsuhiro Nagamatsu, Kenneth B. Wagener, Bora Inci, Fabio Zuluaga, Giovanni Rojas, and James K. Leonard
Macromolecules 2011 Volume 44(Issue 2) pp:313-319
Publication Date(Web):December 29, 2010
DOI:10.1021/ma102072p
The morphology of ADMET-synthesized polyethylene with n-butyl branches precisely spaced on every 39th carbon (EH39) was studied in comparison with an ethylene/1-hexene addition copolymer possessing the same branching probability, the goal being to elucidate the effect of the intramolecular sequence length heterogeneity on the lamella crystal thickness and its distribution. EH39 was found to have an orthorhombic crystalline polymorphism, which is normal for commercialized polyethylenes and different from that of the other ADMET polyethylenes with shorter CH2 spacing (C15, C21). EH39 exhibits a narrow lamella thickness distribution; the average thickness (lc,av.) corresponds exactly to the space length between two consecutive branches, suggesting the complete exclusion of n-butyl branches from the crystal stem. The average thickness, lc,av. mentioned above is also coincident with that obtained from WAXS and SAXS. On the other hand, the 1-hexene copolymer forms much thicker lamellae and a broader thickness distribution than ADMET polyethylene. Here, the average thickness lc,av. determined by TEM observation of the copolymer is 1.5 times larger than that calculated from the most probable ethylene sequence length obtained from 13C NMR, or for a theoretical ethylene sequence length distribution, indicating that the lamellae are composed predominantly of the sparsely branched longer ethylene sequences that are statistically included. The intramolecular sequence distribution is considered significant to determine the lamella thickness and thickness distribution for short chain-branched polyethylenes with a narrow intermolecular chemical composition distribution.
Co-reporter:Paula A. Delgado, David Y. Liu, Zachary Kean, and Kenneth B. Wagener
Macromolecules 2011 Volume 44(Issue 24) pp:9529-9532
Publication Date(Web):November 30, 2011
DOI:10.1021/ma2020529
The synthesis of poly(thienylene vinylenes) (PTV) has been attracting attention due to the low band gaps and high electrical conductivities of these materials, making them applicable for charge storage devices, transparent conductive coatings, and electrochromic devices. Unsubstituted PTV is an intractable polymer that is usually synthesized via a processable precursor. This article reports the synthesis of conjugated polymers using solid-state metathesis conditions, demonstrating the efficiency of this methodology for preparation of a processable polymer, such a 3-dodecyl PTV (P3DDTV). The 3-dodecyl-2,5-dipropenylthiophene was synthesized and subsequently polymerized using ADMET conditions with Grubbs’ second-generation catalyst. The prepolymer film (Mn = 4000 g/mol) was further polymerized in the solid state to give a final product with Mn = 14 000 g/mol (a 3.5-fold increase while in the solid state). The polymer obtained by this methodology exhibited thermal (Tg = 43 °C and Tm = 115 °C) and electrochemical (optical band gap of 1.65 eV and HOMO energy level of 5.35 eV) properties similar to those of PTV polymers synthesized by ADMET polymerization using a high boiling solvent or by cross-coupling reactions.
Co-reporter:James K. Leonard;Diane Turek;Kenneth B. Sloan
Macromolecular Chemistry and Physics 2010 Volume 211( Issue 2) pp:154-165
Publication Date(Web):
DOI:10.1002/macp.200900432
Co-reporter:Brian S. Aitken, Minjae Lee, Matthew T. Hunley, Harry W. Gibson, and Kenneth B. Wagener
Macromolecules 2010 Volume 43(Issue 4) pp:1699-1701
Publication Date(Web):January 20, 2010
DOI:10.1021/ma9024174
Co-reporter:Kathleen L. Opper, Dilyana Markova, Markus Klapper, Klaus Müllen and Kenneth B. Wagener
Macromolecules 2010 Volume 43(Issue 8) pp:3690-3698
Publication Date(Web):March 25, 2010
DOI:10.1021/ma902659y
Polyethylene structures containing precisely placed phosphonic acids were synthesized varying both the frequency of acid appearance along the backbone and the architecture associated with each position. Single, geminal, and benzyl attachment schemes are described with symmetry of placement being an important feature. Altering these precision primary structures has a direct effect on secondary structure where changes in thermal behavior become obvious, particularly in terms of crystallization behavior. It is evident that strong interactions between polymer chains exist, effecting polymer crystallization and solubility depending upon both the length of methylene run-lengths between symmetrically placed acids and whether or not the acid group is protected as the ester or free to participate in hydrogen bonding, which directly influences interchain interaction.
Co-reporter:Jianguo Mei, Brian S. Aitken, Kenneth R. Graham, Kenneth B. Wagener and John R. Reynolds
Macromolecules 2010 Volume 43(Issue 14) pp:5909-5913
Publication Date(Web):June 30, 2010
DOI:10.1021/ma100863h
Co-reporter:Piotr P. Matloka;Zachary Kean
Journal of Polymer Science Part A: Polymer Chemistry 2010 Volume 48( Issue 9) pp:1866-1877
Publication Date(Web):
DOI:10.1002/pola.23941
Abstract
The combination of both chain-internal/chain-end latent crosslinking in a single thermoset polymer system is the subject of this study. A series of linear carbosiloxane/hydrocarbon homopolymers were synthesized by metathesis polycondensation, polymers which serve as the soft phase in the target chain-internal/chain-end latent crosslinked materials. These carbosiloxane/hydrocarbon “soft phase” homopolymers exhibited excellent performance parameters, displaying purely amorphous character with glass transition temperatures ranging between −104 °C and −90 °C depending on the run length of siloxane or hydrocarbon methylene units within the carbosiloxane/hydrocarbon monomer. These soft phase monomers were then copolymerized with latent chain-internal crosslinking carbosilane monomers in the presence of latent chain-end crosslinking molecules thereby generating a new class linear copolymers capable of being moisture cured to produce a new class of silicon-based thermoset systems. Mechanical properties of these thermosets, show breaking strengths up to 0.5 MPa and elongations up to 100%. Both elastic and plastic behavior can be observed in such systems, depending upon the molar ratio of carbosiloxane/hydrocarbon co-monomer and the carbosilane co-monomer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1866–1877, 2010
Co-reporter:Kathleen L. Opper
Macromolecular Rapid Communications 2009 Volume 30( Issue 11) pp:915-919
Publication Date(Web):
DOI:10.1002/marc.200900013
Co-reporter:John E. Schwendeman
Macromolecular Chemistry and Physics 2009 Volume 210( Issue 21) pp:
Publication Date(Web):
DOI:10.1002/macp.200990052
Co-reporter:John E. Schwendeman
Macromolecular Chemistry and Physics 2009 Volume 210( Issue 21) pp:1818-1833
Publication Date(Web):
DOI:10.1002/macp.200900270
Co-reporter:Fabio Zuluaga, Bora İnci, Yoshinobu Nozue, Satoru Hosoda and Kenneth B. Wagener
Macromolecules 2009 Volume 42(Issue 14) pp:4953-4955
Publication Date(Web):June 24, 2009
DOI:10.1021/ma9009005
Co-reporter:Giovanni Rojas and Kenneth B. Wagener
Macromolecules 2009 Volume 42(Issue 6) pp:1934-1947
Publication Date(Web):February 17, 2009
DOI:10.1021/ma802241s
Step-growth acyclic diene metathesis (ADMET) polymerization chemistry followed by exhaustive hydrogenation offers a new alternative in modeling ethylene/1-hexene (EH) copolymers. In contrast to chain-growth chemistry, this new approach produces well-defined, defect-free primary structures. This report describes the synthesis, characterization, and thermal behavior of ADMET-produced polyethylene materials containing either precisely or irregularly spaced butyl branches, the latter to serve as models for ethylene/1-hexene copolymers made via chain-growth chemistry. The thermal behavior of the new materials was studied using differential scanning calorimetry, and detailed NMR and IR analyses permitted the characterization of the primary structures. Properties of the here presented ethylene/1-hexene copolymers models can be varied from semicrystalline to fully amorphous by precise control of comonomer content and spacing.
Co-reporter:Kathleen L. Opper, Birgit Fassbender, Gunther Brunklaus, Hans W. Spiess and Kenneth B. Wagener
Macromolecules 2009 Volume 42(Issue 13) pp:4407-4409
Publication Date(Web):June 15, 2009
DOI:10.1021/ma900884f
Co-reporter:Yuying Wei;Robert Graf Dr.;JohnC. Sworen Dr.;Chi-Yuan Cheng Dr.;CliffordR. Bowers Dr.;KennethB. Wagener Dr.;HansWolfgang Spiess Dr.
Angewandte Chemie International Edition 2009 Volume 48( Issue 25) pp:4617-4620
Publication Date(Web):
DOI:10.1002/anie.200900377
Co-reporter:Paula A. Delgado;Fabio Zuluaga;Piotr Matloka
Journal of Polymer Science Part A: Polymer Chemistry 2009 Volume 47( Issue 19) pp:5180-5183
Publication Date(Web):
DOI:10.1002/pola.23550
Co-reporter:Yuying Wei;Robert Graf Dr.;JohnC. Sworen Dr.;Chi-Yuan Cheng Dr.;CliffordR. Bowers Dr.;KennethB. Wagener Dr.;HansWolfgang Spiess Dr.
Angewandte Chemie 2009 Volume 121( Issue 25) pp:4687-4690
Publication Date(Web):
DOI:10.1002/ange.200900377
Co-reporter:Erik B. Berda
Macromolecular Chemistry and Physics 2008 Volume 209( Issue 15) pp:1601-1611
Publication Date(Web):
DOI:10.1002/macp.200800077
Co-reporter:James K. Leonard;Timothy E. Hopkins;Kim Chaffin
Macromolecular Chemistry and Physics 2008 Volume 209( Issue 14) pp:1485-1494
Publication Date(Web):
DOI:10.1002/macp.200700645
Co-reporter:Erik B. Berda and Kenneth B. Wagener
Macromolecules 2008 Volume 41(Issue 14) pp:5116-5122
Publication Date(Web):June 21, 2008
DOI:10.1021/ma800616h
The synthesis and thermal behavior of polyethylene with precisely placed amphiphilic branches are described. The amphiphilic branches contain tetraethylene glycol as the hydrophilic segment and either pyrene, n-hexyl, or n-tetradecyl moieties as the hydrophobic segment. Monomer and precursor structures have been confirmed by 1H and 13C NMR, elemental analysis, and high-resolution mass spectrometry. The structures of the corresponding polymers have been confirmed by 1H NMR, 13C NMR, and FTIR. Differential scanning calorimetry (DSC) and temperature-modulated DSC (MDSC) were used to study the behavior of these materials in the bulk. The branch distribution was kept constant to probe the effect of changing the hydrophobic graft end group. Altering this group produced significant changes in the observed thermal behavior, implying completely different morphologies for these materials. When the graft end group is a pyrene moiety, the polyolefin backbone crystallizes excluding the pendant branch, which aggregate as confirmed by fluorescence measurements. When this end group is changed to an n-hexyl chain, the branches and the backbone crystallize separately, forming two different crystalline regions. Extending this end group from an n-hexyl to an n-tetradecyl chain allows the branches and backbone to crystallize together, resulting in the inclusion of the branch within the crystal. This material deviates from the well-known trend for ADMET polymers, which show a decrease in melting temperature and enthalpy as the defect size increases.
Co-reporter:Piotr P. Matloka;Zachary Kean;Meghan Greenfield
Journal of Polymer Science Part A: Polymer Chemistry 2008 Volume 46( Issue 12) pp:3992-4011
Publication Date(Web):
DOI:10.1002/pola.22740
Abstract
Acyclic diene metathesis (ADMET) polymerization has been used to synthesize latent reactive processable elastomers constructed of carbosilane and polyether segments. Two types of latent modes have been introduced: “chain-internal” and “chain-end” sites through the use of labile silicon methoxy functionalities. These latent reactive groups are inert when exposed to metathesis conditions allowing formation of the linear copolymer; subsequently exposure to moisture triggers hydrolysis of the methoxy groups and formation of a chemically crosslinked thermoset. The thermoset's mechanical response can be potentially varied from plastic to elastic behavior, depending on the ratio of carbosilane and oligooxyethylene monomers employed. Different lengths of glycols and numbers of methylene groups between them in the polymer backbone have been investigated to explore structure/property relationship. Polymers composed of oligooxyethylenes with eight methylene groups in between them exhibited fully amorphous character, while the ones with up to 20 methylene groups between glycol units showed their semicrystalline nature. The concentration of “chain-internal” and “chain-end” crosslink sites enhances strength; modification to the run length and structure of the soft phase enhances elasticity. Resultant materials have been subjected to mechanical tests using Instron; generated stress/strain curves have shown plastic and elastic behavior. Depending on the composition obtained samples have shown moduli from 0.3 to 115 MPa, tensile strengths from 0.6 to 10 MPa and elongations from 20 to 700%. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3992–4011, 2008
Co-reporter:Ken Wagener
Macromolecular Chemistry and Physics 2007 Volume 208(Issue 1) pp:15-17
Publication Date(Web):22 JAN 2007
DOI:10.1002/macp.200600570
Co-reporter:John E. Schwendeman
Macromolecular Chemistry and Physics 2005 Volume 206(Issue 15) pp:1461-1471
Publication Date(Web):29 JUL 2005
DOI:10.1002/macp.200500078
Summary: Polyethylene can be rendered completely amorphous via the insertion of regularly spaced gem-dimethyl defects along its backbone, where frequency of insertion is the deciding factor in achieving the totally amorphous state. Accurate placement of defects along polyethylene's backbone is achieved with step polymerization metathesis chemistry (the ADMET reaction) rather than using chain polymerization techniques. These gem-dimethyl polyethylene macromolecules, when compared with other ADMET ethylene-based model materials, demonstrate that steric bulk, frequency, and distribution of the defect along the polymer backbone are more important than stereoregularity (tacticity) when the defects are spaced nine carbon atoms or more apart. Comparisons are made between gem-dimethyl “defects” and methyl “defects” in a polyethylene backbone.
Co-reporter:Garrett W. Oakley
Macromolecular Chemistry and Physics 2005 Volume 206(Issue 1) pp:
Publication Date(Web):23 DEC 2004
DOI:10.1002/macp.200400137
Summary: Solid-state olefin metathesis of rigid-rod acyclic diene metathesis (ADMET) polymers and ring-closing metathesis (RCM) have been investigated. 1,4-Dipropoxy-2,5-divinylbenzene (4) was synthesized and used in a bulk ADMET polymerization to produce oligomers of dialkoxy poly(phenylene vinylene). The reaction was continued in the solid state, effectively doubling the molecular weight. Solid-state RCM was investigated with a variety of solid dienes and metathesis catalysts, and demonstrated in low conversions using amide diene 5 with catalysts 9, 13, and 14.
Co-reporter:John E. Schwendeman
Macromolecular Chemistry and Physics 2005 Volume 206(Issue 15) pp:
Publication Date(Web):3 AUG 2005
DOI:10.1002/macp.200590031
Co-reporter:Piotr P. Matloka;John C. Sworen;Fabio Zuluaga
Macromolecular Chemistry and Physics 2005 Volume 206(Issue 2) pp:
Publication Date(Web):18 JAN 2005
DOI:10.1002/macp.200400335
Summary: Latent reactivity has been employed to create processable elastomers constructed of carbosilane and either carbosiloxane or polyether segments. Two types of latent modes have been introduced: “chain-internal” and “chain-end” sites through the use of labile silicon methoxy and trifunctional olefinic functionalities. These latent reactive sites remain inert during formation of the linear copolymer; subsequent exposure to moisture triggers hydrolysis of the methoxy group and formation of a chemically crosslinked thermoset. These “chain-end” sites limit the formation of dangling chains improving the overall mechanical properties of the material. The thermoset's mechanical response can be potentially varied from plastic to elastic behavior, depending on the ratio of hard and soft monomers employed. The concentration of “chain-internal” and “chain-end” crosslink sites enhances strength; modification to the run length and structure of the soft phase enhances elasticity, generating samples having moduli of 6 MPa, tensile strengths of 0.6 MPa and elongations of 400%.
Co-reporter:Stephen E. Lehman Jr.;Shahab Akvan
Journal of Polymer Science Part A: Polymer Chemistry 2005 Volume 43(Issue 23) pp:6134-6145
Publication Date(Web):17 OCT 2005
DOI:10.1002/pola.20965
Two new dimethylvinyl carbene complexes, RuCl2(SIMes)(PPh3)CHCHC(CH3)2 and RuCl2(SIMes)(3BP)2CHCHC(CH3)2, were synthesized from RuCl2(PCp3)2CHCHC(CH3)2. Complex RuCl2(SIMes)(3BP)2CHCHC(CH3)2 does not suffer from the problem of incomplete initiation that has been observed for the other dimethylvinyl carbene complexes, as witnessed by complete and rapid reaction with ethyl vinyl ether. Acyclic diene metathesis (ADMET) polymerization of 1,9-decadiene with these complexes was found to give polymers with chemical and thermal properties similar to those obtained with Schrock's molybdenum catalyst. These complexes are also catalysts for ring-opening metathesis polymerization. The parent complex RuCl2(SIMes)(PCp3)CHCHC(CH3)2 was found to give polyoctenamer with high initial heats of fusion, suggesting a dependence of the “as formed” crystallinity of the polymer on the rate of the ROMP reaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6134–6145, 2005
Co-reporter:A. Cameron Church;James H. Pawlow;K. B. Wagener
Macromolecular Chemistry and Physics 2003 Volume 204(Issue 1) pp:32-39
Publication Date(Web):10 FEB 2003
DOI:10.1002/macp.200290053
It is now evident that ADMET chemistry can be employed to prepare a family of unsaturated carbosilane polymers containing a common backbone decorated with different alkoxysilane pendant groups, demonstrating the generality and potential utility of this chemistry. Four functionalized silicon containing dienes have been synthesized by nucleophilic substitution of the same parent diene monomer containing two reactive silicon-chlorine bonds. These new α,ω-diene monomers have been polymerized under ADMET conditions using the 2nd generation Grubbs's ruthenium catalyst, producing polymers with useful molecular weights. Variation of the pendant group results in differing chemical and physical properties of the resulting polymers. We believe this chemistry offers much to broaden the synthetic pathways to new organosilicon polymers.
Co-reporter:Stephen E Lehman Jr., John E Schwendeman, Patrick M O'Donnell, Kenneth B Wagener
Inorganica Chimica Acta 2003 Volume 345() pp:190-198
Publication Date(Web):10 March 2003
DOI:10.1016/S0020-1693(02)01307-5
A model study was conducted to determine the extent to which olefin isomerization occurs during olefin metathesis of simple olefins with Grubbs ruthenium catalysts and Schrock's molybdenum catalyst under conditions similar to those employed in ADMET polymerization. It was found that the N-heterocyclic carbene (NHC)-ligated ruthenium complex promotes extensive isomerization of both internal and terminal olefins at temperatures of 50–60 °C, whereas the bisphosphine ruthenium complex and Schrock's molybdenum complex do not. Isomerization occurs concurrently with metathesis for the NHC ruthenium complex to produce a mixture of linear olefins of consecutive carbon numbers.A model study was conducted to determine the extent to which olefin isomerization occurs during olefin metathesis of simple olefins. It was found that a N-heterocyclic carbene (NHC)-ligated ruthenium complex promotes extensive isomerization of both internal and terminal olefins at temperatures of 50–60 °C to produce a mixture of linear olefins of consecutive carbon numbers.
Co-reporter:Patrick M. O'Donnell
Journal of Polymer Science Part A: Polymer Chemistry 2003 Volume 41(Issue 18) pp:2816-2827
Publication Date(Web):1 AUG 2003
DOI:10.1002/pola.10852
Precise graft copolymer architectures were achieved by combining the macromonomer technique with the acyclic diene metathesis (ADMET) reaction. These well-defined copolymer structures were the result of proper monomer design before metathesis polymerization. Features such as length of the graft, nature, and concentration of the graft site along the backbone were manipulated via the combination of living atom transfer radical polymerization methods with ADMET chemistry. Furthermore, the physical behavior of these materials was altered such that they presented dissimilar thermal properties of either the homopolymers or random copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2816–2827, 2003
Co-reporter:T.E. Hopkins;K.B. Wagener
Advanced Materials 2002 Volume 14(Issue 23) pp:
Publication Date(Web):25 NOV 2002
DOI:10.1002/1521-4095(20021203)14:23<1703::AID-ADMA1703>3.0.CO;2-5
The synthesis and optical properties of a variety of chiral polyolefins are reviewed. The polymers are separated into four categories: hydrocarbon-based chiral polyolefins, chiral polyolefins from achiral monomers, chiral polyolefins with aromatic side chains, and chiral polyolefins bearing branched amino acids. The polymers were synthesized using Ziegler–Natta, anionic, radical, and acyclic diene metathesis (ADMET) polymerization techniques.
Co-reporter:Kenneth B. Wagener;Regina Schitter;Krystyna R. Brzezinska
Journal of Polymer Science Part A: Polymer Chemistry 2000 Volume 38(Issue 9) pp:1544-1550
Publication Date(Web):31 MAR 2000
DOI:10.1002/(SICI)1099-0518(20000501)38:9<1544::AID-POLA18>3.0.CO;2-J
Reactive methoxy-functionalized carbosilane and carbosiloxane dienes can be either homopolymerized or copolymerized via acyclic diene metathesis (ADMET) polycondensation chemistry to produce reactive materials with mechanical behavior dependent on the molar ratios of the comonomers. The methoxy-functional group within the polycarbosilane repeat unit remains inert during the metathesis polymerization and can be triggered subsequently with water to generate crosslinks between polymer chains. In this way, linear, thermoplastic copolymers can be prepared with ADMET chemistry and converted into crosslinked, thermoset copolymers upon exposure to moisture. Crosslinked films containing 5–10% of the crosslinked hard segment are soft and flexible materials. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1544–1550, 2000
Co-reporter:Yoshinobu Nozue ; Yasutoyo Kawashima ; Shuichiro Seno ; Tatsuhiro Nagamatsu ; Satoru Hosoda ; Erik B. Berda ; Giovanni Rojas ; Travis W. Baughman
Macromolecules () pp:
Publication Date(Web):May 13, 2011
DOI:10.1021/ma200145k
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