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Marc A Hillmyer - One of the best experts on this subject based on the ideXlab platform.
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Aliphatic Polyester thermoplastic elastomers containing hydrogen bonding ureidopyrimidinone endgroups
Biomacromolecules, 2019Co-Authors: Annabelle Watts, Marc A HillmyerAbstract:Polylactide- block-poly(γ-methyl-e-caprolactone)- block-polylactide (LML) is a sustainable thermoplastic elastomer (TPE) candidate that exhibits competitive mechanical properties as compared to traditional styrenic TPEs. The relatively low glass transition temperature of the polylactide endblocks, however, results in stress relaxation and low levels of elastic recovery. We report the synthesis and characterization of poly(γ-methyl-e-caprolactone) (PMCL) and LML end-functionalized with ureidopyrimidinone (UPy) hydrogen-bonding moieties to improve the elastic performance of these polymers. Although UPy-functionalized PMCL shows dynamical mechanical behavior that is distinct from the unfunctionalized homopolymer, it does not exhibit elastomeric behavior at room temperature. The addition of UPy endgroups to LML increases the ultimate tensile strength, elongation at break, and tensile toughness compared to unfunctionalized LML. Stress relaxation studies at a fixed strain show reduced levels of stress relaxation in LML with UPy endgroups. The stress relaxation was further reduced by including semicrystalline poly(( S, S)-lactide) as endblocks with UPy endgroups.
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entropically driven macrolide polymerizations for the synthesis of Aliphatic Polyester copolymers using titanium isopropoxide
Macromolecules, 2019Co-Authors: Adrian G Amador, Annabelle Watts, Angelika E Neitzel, Marc A HillmyerAbstract:Thermal and mechanical properties of sustainable Aliphatic Polyesters can be tuned through the synthesis of copolymers. The synthesis of two 14-membered macrolides are reported: a cyclic tetraester with alternating lactic acid (LA) and 3-hydroxypropionic acid (3HP) units and a cyclic diester with alternating glycolic acid (GA) and 2-methyl-1,3-propanediol (2MD) units. Ring-opening transesterification polymerization (ROTEP) of these macrolides to yield poly(LA-stat-3HP) and poly(GA-alt-2MD), respectively, were found to be modestly endothermic (ΔHp° = 2.0 and 0.5 kJ mol–1, respectively) and endoentropic (ΔSp° = 27 and 23 J mol–1 K–1, respectively). Inexpensive and nontoxic titanium isopropoxide Ti(Oi-Pr)4 functions as an active catalyst for these entropically driven ROTEPs, achieving high conversions (>90%) in under 1 h. The polymerizations exhibit control over molar mass with dispersity values <1.7. poly(GA-alt-2MD) is an amorphous polymer with a low glass transition temperature near −30 °C. poly(LA-co-3HP...
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strong resilient and sustainable Aliphatic Polyester thermoplastic elastomers
Biomacromolecules, 2017Co-Authors: Annabelle Watts, Naruki Kurokawa, Marc A HillmyerAbstract:Thermoplastic elastomers (TPEs) composed of ABA block polymers exhibit a wide variety of properties and are easily processable as they contain physical, rather than chemical, cross-links. Poly(γ-methyl-e-caprolactone) (PγMCL) is an amorphous polymer with a low entanglement molar mass (Me = 2.9 kg mol–1), making it a suitable choice for tough elastomers. Incorporating PγMCL as the midblock with polylactide (PLA) end blocks (fLA = 0.17) results in TPEs with high stresses and elongations at break (σB = 24 ± 2 MPa and eB = 1029 ± 20%, respectively) and low levels of hysteresis. The use of isotactic PLA as the end blocks (fLLA = 0.17) increases the strength and toughness of the material (σB = 30 ± 4 MPa, eB = 988 ± 30%) due to its semicrystalline nature. This study aims to demonstrate how the outstanding properties in these sustainable materials are a result of the entanglements, glass transition temperature, segment–segment interaction parameter, and crystallinity, resulting in comparable properties to the co...
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Aliphatic Polyester block polymer design
Macromolecules, 2016Co-Authors: Deborah K Schneiderman, Marc A HillmyerAbstract:Aliphatic Polyester block polymers constitute a highly useful and amazingly versatile class of self-assembled materials. Analogous to styrenic block polymers in both design and function, the property profiles of these degradable materials can be precisely tailored by altering the chemical structure of the components. Driven by this ideal, we have examined the impact of n-alkyl substituents on the polymerization thermodynamics and kinetics of substituted δ-valerolactone monomers and developed guiding design principles based on critical structure–property relationships in the resulting Aliphatic Polyesters. Under bulk room temperature conditions the polymerization rate depends strongly on substituent position and exhibits a more modest dependence on alkyl length (from −CH3 to −(CH2)8CH3). The enthalpy and entropy of polymerization are significantly influenced by substituent position, but both are largely insensitive to n-alkyl length. However, the physical properties of the resulting Aliphatic Polyesters de...
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divergent mechanistic avenues to an Aliphatic Polyesteracetal or Polyester from a single cyclic esteracetal
ACS Macro Letters, 2014Co-Authors: Angelika E Neitzel, Matthew A Petersen, Efrosini Kokkoli, Marc A HillmyerAbstract:The cyclic esteracetal 2-methyl-1,3-dioxane-4-one (MDO) was polymerized in bulk using diethyl zinc as the catalyst and benzyl alcohol as the initiator to yield either the corresponding Polyesteracetal (PMDO) or the Aliphatic Polyester poly(3-hydroxypropionic acid) (PHPA) at low and high catalyst concentrations, respectively. Spectral analysis gave evidence for distinct propagating species in the two catalyst concentration regimes. At low zinc concentrations ring opening by attack of the initiating species at the acetal functionality, yielding a zinc carboxylate, followed by propagation to yield pure PMDO was implicated. At high zinc concentrations we propose that ring opening via attack at the ester functionality produced a labile zinc hemiacetal, which rapidly and irreversibly expelled acetaldehyde to form a propagating zinc alkoxide and ultimately pure PHPA. Initial rate studies indicated that the rate of PHPA formation had a second-order dependence on zinc concentration; in contrast, the rate of PMDO f...
Orlando J Rojas - One of the best experts on this subject based on the ideXlab platform.
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mussel inspired reinforcement of a biodegradable Aliphatic Polyester with bamboo fibers
Journal of Cleaner Production, 2021Co-Authors: Gonghua Hong, Haitao Cheng, Shuangbao Zhang, Orlando J RojasAbstract:Abstract Natural fiber-reinforced biocomposites displaying light weight, low thermal conductivity and reduced environmental footprint are increasingly relevant in structural, packaging, cementitious and masonry materials. However, the poor interfacial compatibility between fibers and typical polymers has limited the development of mechanical strength and water resistance. Here, we report a green, facile and effective method inspired by nature to promote interfacial adhesion in biocomposites based on a biodegradable Aliphatic Polyester (polybutylene succinate, PBS). For this purpose, PBS was reinforced with bamboo fibers modified with (3-aminopropyl) triethoxysilane and polydopamine (PDA). The PDA deposition and covalent adhesion with the fibers were promoted by self-polymerization and Michael addition and/or Schiff based secondary reactions. A distinct improvement in reinforcement was achieved together with gains in performance, including tensile strength (70%), tensile modulus (25%), flexural strength (37%), flexural modulus (24%) and impact strength (63%). The results far exceeded those measured for other fiber-reinforced biocomposites while simultaneously introduced water resistance.
Peng Liu - One of the best experts on this subject based on the ideXlab platform.
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adsorption properties of hyperbranched Aliphatic Polyester grafted attapulgite towards heavy metal ions
Journal of Hazardous Materials, 2007Co-Authors: Peng Liu, Tingmei WangAbstract:The AB(2) type monomer, 2,2-bis (hydroxymethyl) propionic acid (bis-MPA), was successfully grafted from the surfaces of the amino groups modified attapulgite nano-fibrillar clay (A-ATP) via a melt polycondensation method with p-toluenesulfonic acid (p-TSA) as catalyst. The competitive adsorption properties of the hyperbranched Aliphatic Polyester grafted attapulgite (HAPE-ATP) towards the heavy metal ions (Cu(II), Hg(II), Zn(II), and Cd(II)) were investigated preliminarily.
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hyperbranched Aliphatic Polyester grafted attapulgite via a melt polycondensation process
Applied Clay Science, 2007Co-Authors: Peng LiuAbstract:Abstract A new process for the facile fabrication of the hyperbranched polymer grafted nano-surfaces was developed in the present work. The AB2 type monomer, 2, 2-bis(hydroxymethyl)propionic acid (bis-MPA), was successfully grafted from the surfaces of the amino groups modified attapulgite nano-fibrillar clay (amino-ATP) via a melt polycondensation method with p-toluenesulfonic acid (p-TSA) as catalyst. Higher percentage of grafting (PG%) was achieved within shorter polymerizing time, compared with the product from the solution polycondensation method within longer polymerizing time. The surface composition and crystal structure of the hyperbranched Aliphatic Polyester grafted attapulgite (HAPE-ATP) were also characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The transmission electron microscopy (TEM) analysis results showed that the dispersibility of the nano-fibrillar clay in organic solvent was improved after the graft polymerization.
Annabelle Watts - One of the best experts on this subject based on the ideXlab platform.
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Aliphatic Polyester thermoplastic elastomers containing hydrogen bonding ureidopyrimidinone endgroups
Biomacromolecules, 2019Co-Authors: Annabelle Watts, Marc A HillmyerAbstract:Polylactide- block-poly(γ-methyl-e-caprolactone)- block-polylactide (LML) is a sustainable thermoplastic elastomer (TPE) candidate that exhibits competitive mechanical properties as compared to traditional styrenic TPEs. The relatively low glass transition temperature of the polylactide endblocks, however, results in stress relaxation and low levels of elastic recovery. We report the synthesis and characterization of poly(γ-methyl-e-caprolactone) (PMCL) and LML end-functionalized with ureidopyrimidinone (UPy) hydrogen-bonding moieties to improve the elastic performance of these polymers. Although UPy-functionalized PMCL shows dynamical mechanical behavior that is distinct from the unfunctionalized homopolymer, it does not exhibit elastomeric behavior at room temperature. The addition of UPy endgroups to LML increases the ultimate tensile strength, elongation at break, and tensile toughness compared to unfunctionalized LML. Stress relaxation studies at a fixed strain show reduced levels of stress relaxation in LML with UPy endgroups. The stress relaxation was further reduced by including semicrystalline poly(( S, S)-lactide) as endblocks with UPy endgroups.
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entropically driven macrolide polymerizations for the synthesis of Aliphatic Polyester copolymers using titanium isopropoxide
Macromolecules, 2019Co-Authors: Adrian G Amador, Annabelle Watts, Angelika E Neitzel, Marc A HillmyerAbstract:Thermal and mechanical properties of sustainable Aliphatic Polyesters can be tuned through the synthesis of copolymers. The synthesis of two 14-membered macrolides are reported: a cyclic tetraester with alternating lactic acid (LA) and 3-hydroxypropionic acid (3HP) units and a cyclic diester with alternating glycolic acid (GA) and 2-methyl-1,3-propanediol (2MD) units. Ring-opening transesterification polymerization (ROTEP) of these macrolides to yield poly(LA-stat-3HP) and poly(GA-alt-2MD), respectively, were found to be modestly endothermic (ΔHp° = 2.0 and 0.5 kJ mol–1, respectively) and endoentropic (ΔSp° = 27 and 23 J mol–1 K–1, respectively). Inexpensive and nontoxic titanium isopropoxide Ti(Oi-Pr)4 functions as an active catalyst for these entropically driven ROTEPs, achieving high conversions (>90%) in under 1 h. The polymerizations exhibit control over molar mass with dispersity values <1.7. poly(GA-alt-2MD) is an amorphous polymer with a low glass transition temperature near −30 °C. poly(LA-co-3HP...
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strong resilient and sustainable Aliphatic Polyester thermoplastic elastomers
Biomacromolecules, 2017Co-Authors: Annabelle Watts, Naruki Kurokawa, Marc A HillmyerAbstract:Thermoplastic elastomers (TPEs) composed of ABA block polymers exhibit a wide variety of properties and are easily processable as they contain physical, rather than chemical, cross-links. Poly(γ-methyl-e-caprolactone) (PγMCL) is an amorphous polymer with a low entanglement molar mass (Me = 2.9 kg mol–1), making it a suitable choice for tough elastomers. Incorporating PγMCL as the midblock with polylactide (PLA) end blocks (fLA = 0.17) results in TPEs with high stresses and elongations at break (σB = 24 ± 2 MPa and eB = 1029 ± 20%, respectively) and low levels of hysteresis. The use of isotactic PLA as the end blocks (fLLA = 0.17) increases the strength and toughness of the material (σB = 30 ± 4 MPa, eB = 988 ± 30%) due to its semicrystalline nature. This study aims to demonstrate how the outstanding properties in these sustainable materials are a result of the entanglements, glass transition temperature, segment–segment interaction parameter, and crystallinity, resulting in comparable properties to the co...
Gonghua Hong - One of the best experts on this subject based on the ideXlab platform.
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mussel inspired reinforcement of a biodegradable Aliphatic Polyester with bamboo fibers
Journal of Cleaner Production, 2021Co-Authors: Gonghua Hong, Haitao Cheng, Shuangbao Zhang, Orlando J RojasAbstract:Abstract Natural fiber-reinforced biocomposites displaying light weight, low thermal conductivity and reduced environmental footprint are increasingly relevant in structural, packaging, cementitious and masonry materials. However, the poor interfacial compatibility between fibers and typical polymers has limited the development of mechanical strength and water resistance. Here, we report a green, facile and effective method inspired by nature to promote interfacial adhesion in biocomposites based on a biodegradable Aliphatic Polyester (polybutylene succinate, PBS). For this purpose, PBS was reinforced with bamboo fibers modified with (3-aminopropyl) triethoxysilane and polydopamine (PDA). The PDA deposition and covalent adhesion with the fibers were promoted by self-polymerization and Michael addition and/or Schiff based secondary reactions. A distinct improvement in reinforcement was achieved together with gains in performance, including tensile strength (70%), tensile modulus (25%), flexural strength (37%), flexural modulus (24%) and impact strength (63%). The results far exceeded those measured for other fiber-reinforced biocomposites while simultaneously introduced water resistance.