[ { "id": "authors:eepjv-w4b46", "collection": "authors", "collection_id": "eepjv-w4b46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180412-141958464", "type": "article", "title": "Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers", "author": [ { "family_name": "Haugan", "given_name": "Ingrid N.", "orcid": "0000-0002-8406-8939", "clpid": "Haugan-I-N" }, { "family_name": "Maher", "given_name": "Michael J.", "orcid": "0000-0003-0577-3726", "clpid": "Maher-M-J" }, { "family_name": "Chang", "given_name": "Alice B.", "orcid": "0000-0001-5036-2681", "clpid": "Chang-Alice-B" }, { "family_name": "Lin", "given_name": "Tzu-Pin", "orcid": "0000-0001-7041-7213", "clpid": "Lin-Tzu-Pin" }, { "family_name": "Grubbs", "given_name": "Robert H.", "orcid": "0000-0002-0057-7817", "clpid": "Grubbs-R-H" }, { "family_name": "Hillmyer", "given_name": "Marc A.", "orcid": "0000-0001-8255-3853", "clpid": "Hillmyer-M-A" }, { "family_name": "Bates", "given_name": "Frank S.", "orcid": "0000-0003-3977-1278", "clpid": "Bates-F-S" } ], "abstract": "The linear viscoelastic behavior of poly(norbornene)-graft-poly(\u00b1-lactide) was investigated as a function of grafting density and overall molar mass. Eight sets of polymers with grafting densities ranging from 0 to 100% were synthesized by living ring-opening metathesis copolymerization. Within each set, the graft chain molar mass and spacing between grafts were fixed, while the total backbone length was varied. Dynamic master curves reveal that these polymers display Rouse and reptation dynamics with a sharp transition in the zero-shear viscosity data, demonstrating that grafting density strongly impacts the entanglement molar mass. The entanglement modulus (G_e) scales with inverse grafting density (n_g) as G_e \u223c n_g^(1.2) and G_e \u223c n_g^0 in accordance with scaling theory in the high and low grafting density limits, respectively. However, a sharp transition between these limiting behaviors occurs, which does not conform to existing theoretical models for graft polymers. A molecular interpretation based on thin flexible chains at low grafting density and thick semiflexible chains at high grafting density anticipates the sharp transition between the limiting dynamical regimes.", "doi": "10.1021/acsmacrolett.8b00116", "issn": "2161-1653", "publisher": "American Chemical Society", "publication": "ACS Macro Letters", "publication_date": "2018-05-15", "series_number": "5", "volume": "7", "issue": "5", "pages": "525-530" }, { "id": "authors:t20t9-bay78", "collection": "authors", "collection_id": "t20t9-bay78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180719-153832844", "type": "article", "title": "Utility of a Ruthenium Metathesis Catalyst for the Preparation of End-Functionalized Polybutadiene", "author": [ { "family_name": "Hillmyer", "given_name": "Marc A.", "orcid": "0000-0001-8255-3853", "clpid": "Hillmyer-M-A" }, { "family_name": "Nguyen", "given_name": "SonBinh T.", "clpid": "Nguyen-SonBinh-T" }, { "family_name": "Grubbs", "given_name": "Robert H.", "orcid": "0000-0002-0057-7817", "clpid": "Grubbs-R-H" } ], "abstract": "The polymerization of cyclooctadiene (COD) in the presence of an allylic difunctionalized chain transfer agent (1) by a ruthenium metathesis catalyst (Ru) was accomplished. Deprotection of the resulting acetate end-functionalized polybutadiene was performed, leading to commercially important 1,4-hydroxytelechelic polybutadiene (HTPBD) with number average functionalities close to 2.0. The polymerizations were performed at high monomer concentrations or in the absence of solvent, and the robust nature of Ru allowed the use of high monomer to catalyst ratios (\u223c0.01 mol % Ru relative to total olefin). Investigation of the metathesis of olefin alcohols with Ru showed that side reactions may complicate the use of these compounds as chain transfer agents in metathesis polymerizations. The kinetics of this Ru-catalyzed ring-opening metathesis polymerization with added chain transfer agent was also investigated.", "doi": "10.1021/ma961316n", "issn": "0024-9297", "publisher": "American Chemical Society", "publication": "Macromolecules", "publication_date": "1997-02-24", "series_number": "4", "volume": "30", "issue": "4", "pages": "718-721" }, { "id": "authors:n0adb-52r40", "collection": "authors", "collection_id": "n0adb-52r40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180313-145155358", "type": "article", "title": "Chain Transfer in the Ring-Opening Metathesis Polymerization of Cyclooctadiene Using Discrete Metal Alkylidenes", "author": [ { "family_name": "Hillmyer", "given_name": "Marc A.", "orcid": "0000-0001-8255-3853", "clpid": "Hillmyer-M-A" }, { "family_name": "Grubbs", "given_name": "Robert H.", "orcid": "0000-0002-0057-7817", "clpid": "Grubbs-R-H" } ], "abstract": "The ring-opening metathesis polymerization of cyclooctadiene (COD) in the presence of a\ndifunctional chain transfer agent (CTA) was investigated. The effect of the CTA structure and choice of\nmetathesis catalyst on the overall efficiency of the polymerization reaction is discussed. A separation of\nthe oxygen functionality from the olefin in the CTA by two methylene units significantly enhances the\nstability of the discrete, tungsten-based metathesis catalyst used for these polymerizations. Furthermore,\na more robust well-defined metathesis catalyst based on molybdenum was more effective than the\ntungsten-based catalyst. The preparation oflow-molecular-weight hydroxytelechelic polybutadienes with\none type of regiochemistry, number-average functionalities that approach 2.0, and in high yield was\naccomplished.", "doi": "10.1021/ma00129a027", "issn": "0024-9297", "publisher": "American Chemical Society", "publication": "Macromolecules", "publication_date": "1995-12-01", "series_number": "25", "volume": "28", "issue": "25", "pages": "8662-8667" }, { "id": "authors:cz91d-qg079", "collection": "authors", "collection_id": "cz91d-qg079", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180720-123814160", "type": "article", "title": "Preparation of hydroxytelechelic poly(butadiene) via ring-opening metathesis polymerization employing a well-defined metathesis catalyst", "author": [ { "family_name": "Hillmyer", "given_name": "Marc A.", "orcid": "0000-0001-8255-3853", "clpid": "Hillmyer-M-A" }, { "family_name": "Grubbs", "given_name": "Robert H.", "orcid": "0000-0002-0057-7817", "clpid": "Grubbs-R-H" } ], "abstract": "In this paper we show that ring-opening metathesis polymerization (ROMP) using a discrete metal alkylidene catalyst offers another alternative polymerization technique that is applicable to the synthesis of well-defined HTPBD.", "doi": "10.1021/ma00056a051", "issn": "0024-9297", "publisher": "American Chemical Society", "publication": "Macromolecules", "publication_date": "1993-02-15", "series_number": "4", "volume": "26", "issue": "4", "pages": "872-874" }, { "id": "authors:edsg2-7k650", "collection": "authors", "collection_id": "edsg2-7k650", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180720-131738319", "type": "article", "title": "Aqueous ring-opening metathesis polymerization of carboximide-functionalized 7-oxanorbornenes", "author": [ { "family_name": "Hillmyer", "given_name": "Marc A.", "orcid": "0000-0001-8255-3853", "clpid": "Hillmyer-M-A" }, { "family_name": "Lepetit", "given_name": "Christine", "clpid": "Lepetit-C" }, { "family_name": "McGrath", "given_name": "Dominic V.", "clpid": "McGrath-D-V" }, { "family_name": "Novak", "given_name": "Bruce M.", "clpid": "Novak-B-M" }, { "family_name": "Grubbs", "given_name": "Robert H.", "orcid": "0000-0002-0057-7817", "clpid": "Grubbs-R-H" } ], "abstract": "The ring-opening metathesis polymerization (ROMP) of exo-N-methyl-7-oxabicyclo[2.2.1]-hept-5-ene-2,3-dicarboximide (1) was accomplished in aqueous solution under mild conditions using the simple ruthenium(II) coordination complex Ru^(II)(H_2O)_6(tos)_2 (tos = p-toluenesulfonate) (2). The polymerization yield was nearly quantitative. The resultant high molecular weight polymer (poly-1) exhibited a glass transition temperature (T_g) of 225 \u00b0C and was thermally stable up to 402 \u00b0C. The thermal and radiative stabilities of poly-1 were further investigated. Poly-1 was hydrogenated to yield its saturated analogue, which had a lower T_g (170 \u00b0C) but a higher temperature of decomposition (430 \u00b0C). Complex 2 was deactivated by coordination of free maleimides formed during the polymerization of carboximide-functionalized monomers capable of undergoing retro Diels-Alder chemistry. The scope of this polymerization was therefore limited to carboximide-functionalized monomers that are stable toward retro Diels-Alder reactions at the polymerization temperature. Both ruthenium (II)-1 and ruthenium(II)-N-methylmaleimide olefin complexes were identified.", "doi": "10.1021/ma00039a004", "issn": "0024-9297", "publisher": "American Chemical Society", "publication": "Macromolecules", "publication_date": "1992-06-22", "series_number": "13", "volume": "25", "issue": "13", "pages": "3345-3350" } ]