245533S
THE CREATION OF NET ZERO CARBON POLYMERS WITH FAVORABLE CHEMICAL AND FUNCTIONAL PROPERTIES. THE OVERARCHING GOAL OF CPW IS TO UNRAVEL FUNDAMENTAL MECHANISMS OF REACTIONS AND INTERACTIONS AT THE MOLECULAR AND MESO SCALE THAT WILL GUIDE THE DESIGN AND SYNTHESIS OF POLYMERS FROM CARBON-NEGATIVE AND CARBON-NEUTRAL WASTE FEEDSTOCKS AND ACHIEVE DESIRABLE PROPERTIES THROUGH TAILORED AND PRECISION CONSTRUCTION AND DECONSTRUCTION. OUR RESEARCH THEMES ARE IN LINE WITH NSFÂ S BIG IDEAS ON SUSTAINABILITY, INCLUDING THE TRANSFORMATION OF EDUCATION PATHWAYS TO HELP BROADEN PARTICIPATION IN STEM. CPW WILL FULLY INTEGRATE MODELING AND EXPERIMENT, SPANNING FROM MOLECULAR TO MACROMOLECULAR TO MACROSCOPIC SCALE, TO ULTIMATELY ACHIEVE A PARADIGM-SHIFTING ADVANCE TOWARD SUSTAINABLE POLYMER CIRCULARITY. OUR RESEARCH GOALS ARE TO: 1) DEVELOP FUNDAMENTAL UNDERSTANDING OF HOW TO TRANSFORM CARBON-NEGATIVE AND NEUTRAL WASTE FEEDSTOCKS INTO REACTIVE MONOMERS AND INTERMEDIATES; 2) UNRAVEL SYNTHETIC APPROACHES AND MECHANISTIC UNDERSTANDING TO GENERATE DIVERSE POLYMERS WITH FUNCTIONALITIES THAT ALLOW DECONSTRUCTION UNDER DESIRED CONDITIONS; 3) ESTABLISH PREDICTIVE MODELING APPROACHES TO ACHIEVE FUNDAMENTAL UNDERSTANDING OF THE ROLES OF PRECISION COMPOSITIONS AND FUNCTIONAL GROUP PLACEMENTS ON PROGRAMMABLE PROCESSES AT MACROMOLECULAR AND MESOSCOPIC SCALE. THESE GOALS WILL BE PURSUED IN THREE THRUSTS: THRUST I. MONOMER SYNTHESIS USING CARBON EMISSIONS AND WASTE STREAMS AS FEEDSTOCKS; THRUST II. DEGRADABLE/DEPOLYMERIZABLE POLYMERS MIMICKING COMMODITY POLYMERS; THRUST III. PREDICTIVE MODELING FOR CORRELATION BETWEEN STRUCTURES AND FUNCTIONS. CATALYSIS, POLYMERIZATION, AND MODELING. BY CONSOLIDATING COMPLEMENTARY EXPERTISE, CPW WILL EMERGE AS A MAJOR INTELLECTUAL ENTERPRISE TO PROVIDE FUNDAMENTAL INSIGHTS AT THE MOLECULAR, POLYMER, AND MATERIAL (PLASTIC) LEVELS. WE PROPOSE THREE CLOSELY INTERCONNECTED THRUSTS THAT ARE CENTERED ON A CRADLE-TO-CRADLE STRATEGY TO ADDRESS RECYCLING AND UPCYCLING OF NEXT-GENERATION POLYMERS THROUGH ROBUST AND EFFICIENT CHEMICAL APPROACHES. THE PROPOSED FUNDAMENTAL RESEARCH WILL: 1) RESULT IN CATALYTIC APPROACHES TO PRODUCE CO2 AND WASTE BIOMASS-DERIVED INTERMEDIATES AND MONOMERS DESIRABLE FOR (CO)POLYMERIZATION; 2) DISCOVER NEW CHEMISTRY AND MACROMOLECULAR COMPOSITIONS TOWARD PREDICTABLE DEGRADABILITY AND DEPOLYMERIZABILITY; 3) ELUCIDATE THE COMPLEX STRUCTUREREACTIVITY RELATIONSHIP TOWARD CONSTRUCTION AND DECONSTRUCTION OF POLYMERS AT THE MOLECULAR AND MESO-SCALE THROUGH EXPERIMENTS AND MODELING. THESE GOALS REQUIRE INTERDISCIPLINARY EXPERTISE AND CLOSE COLLABORATIONS, THUS NOT ACHIEVABLE BY INDIVIDUAL PIS. THE INTERCONNECTED EFFORTS ON WASTE TRANSFORMATION, MONOMER DESIGN, CONTROLLED POLYMERIZATION, PRECISION DECONSTRUCTION, COUPLED WITH PREDICTIVE MODELING, REQUIRES A CENTER THAT COMBINES THESE COMPLEMENTARY SKILLS AND RESOURCES TO TACKLE SUCH COMPLEX AND INTEGRATED CHALLENGES. THE COLLABORATIVE CENTER EFFORTS WILL ALLOW THE SYNTHETIC TEAM TO WORK CLOSELY ON CATALYSIS, MACROMOLECULAR SYNTHESIS, AND THE MULTISCALE MODELING INITIATIVE TO PROVIDE MUCH-NEEDED PREDICTIVE FEEDBACKS TO ACCELERATE THE CHEMICAL DESIGN AND SYNTHESIS EFFORTS. COMPLETING THE PROPOSED RESEARCH WILL LEAD TO A NEW FAMILY OF NEXT-GENERATION CARBON-NEGATIVE AND NEUTRAL POLYMERS THAT RIVAL PETROCHEMICAL COMMODITY POLYMERS AS WELL AS IDENTIFY CHEMICAL DESIGN PARAMETERS TO ACHIEVE THE DEGRADABILITY IN A SUSTAINABLE MANNER. THE SUCCESS OF THESE TARGETS COULD RESHAPE THE NEXT CENTURYÂ S EFFORTS ON SUSTAINABLE POLYMERSKUKSENOK, CU) ONE OF THE MAJOR CHALLENGES IN SUCCESSFUL UTILIZATION OF WASTE PRODUCTS IS ACHIEVING PROPERTIES OF THE RESULTING POLYMER MATERIALS COMPARABLE TO THOSE OF COMMODITY POLYMERS. OVERARCHING GOAL OF THRUST III IS TO DEVELOP PREDICTIVE MULTISCALE MODELING APPROACHES TO GUIDE SYNTHESIS OF SUITABLE PRECURSORS FROM THE WASTE PRODUCTS AND SYNTHESIS OF POLYMERS WITH TARGET PROPERTIES FROM THESE PRECURSORS. IN PHASE I, WE WILL FOCUS ON FUNDAMENTAL UNDERSTANDING OF HOW CHEMICAL COMPOSITIONS OF PRECURSORS SYNTHESIZED FROM WASTE PRODUCTS AND CHEMICAL NATURE AND PLACEMENT OF FUNCTIONAL GROUPS CAN CONTROLLABLY TAILOR MACROMOLECULAR ARCHITECTURES, MOLECULAR WEIGHTS DISTRIBUTION, CHAIN PACKING, AND DEGREE OF CRYSTALLINITY THAT ARE CRITICAL TO ACHIEVE TARGET PROPERTIES AND TO ENABLE CIRCULAR DECONSTRUCTION AND RECONSTRUCTION. TO DO SO, WE WILL DEVELOP SUITABLE MESOSCALE MODELING APPROACH THAT IS CAPABLE OF IDENTIFYING EFFECTS OF CHEMICAL COMPOSITIONS OF PRECURSORS AND PLACEMENT OF FUNCTIONAL GROUPS ON THE STRUCTURAL CHARACTERISTICS OF SYNTHESIZED POLYMERS. COMPUTER SIMULATIONS WILL PROVIDE FEEDBACK TO THRUSTS I AND II TO IDENTIFY THE MOST PROMISING SYNTHETIC CANDIDATES. THE COMPUTATIONAL MODELING WILL BE INFORMED BY THE EXPERIMENTAL RESULTS AND PROVIDE INSIGHTS TO THE EXPERIMENTAL OBSERVATIONS. WE WILL UTILIZE DISSIPATIVE PARTICLE DYNAMICS (DPD), AN EFFICIENT MESOSCALE COARSE-GRAINED APPROACH1- 4, TO PROBE THE EFFECTS OF CHEMICAL REACTIVITY AND DIFFUSION OF ALL SPECIES (MONOMERS AND MACROMOLECULAR FRAGMENTS WITH DIFFERENT DEGREES OF POLYMERIZATION) ON THE OBSERVED MORPHOLOGIES AND ON OUTCOMES OF CONTROLLED DECONSTRUCTION AND RECONSTRUCTION PROCESSES. DPD USES SOFT REPULSIVE INTERACTIONS BETWEEN THE BEADS REPRESENTING CLUSTERS OF ATOMS, THEREBY ALLOWING A LOW COMPUTATIONAL COST OF SIMULATIONS AND MAKING LARGER SYSTEMS COMPUTATIONALLY ACCESSIBLE (COMPARED TO MOLECULAR DYNAMICS(MD)).3-5 DUE TO ITS COMPUTATIONAL EFFICIENCY AND ALGORITHMIC SIMPLICITY, DPD HAS BEEN WIDELY USED TO MODEL A VARIETY OF COMPLEX SYSTEMS4-10. DPD ALLOWS ONE TO CAPTURE DIFFUSION AND REACTION PROCESSES IN MULTICOMPONENT SYSTEMS, AND TO INTRODUCE A BROAD RANGE OF INTERACTIONS BETWEEN VARIOUS SPECIES BASED ON THEIR AFFINITIES IN A STRAIGHTFORWARD MANNER3, 4, THEREBY THIS APPROACH IS WELL SUITED TO PROBE A RANGE OF INTERACTIONS BETWEEN DIFFERENT PRECURSORS. THE MODELING RESULTS WILL ALLOW US TO CHARACTERIZE MOLECULAR WEIGHT DISTRIBUTION, DISPERSITY, DYNAMICS OF THE CHAIN PACKING PROCESSES, AND MORPHOLOGIES OF THE ASSEMBLED STRUCTURES FOR POLYMERS OF VARIOUS COMPOSITIONS. THE MODELING OUTCOMES WILL BE USED TO OPTIMIZE CHEMICAL SYNTHESIS, COMPOSITION, AND PLACEMENT OF FUNCTIONAL GROUPS TO CONTROLLABLY TUNE THE DEGREE OF CRYSTALLINITY, AND ULTIMATELY THERMAL AND MECHANICAL PROPERTIES. COMPUTATIONAL INSIGHTS WILL ALSO HELP TO UNDERSTAND THE FUNDAMENTALS OF CONTROLLED DECONSTRUCTION AND RECONSTRUCTION PROCESSES. INTRODUCING MESOSCALE MODELING APPROACH AND RELEVANT BACKGROUND. THE PARTICLES IN DPD REPRESENT COLLECTIONS OF ATOMS; THE MOTION OF THE PARTICLES IS GOVERNED BY NEWTONÂ S EQUATIONS OF MOTION, WHERE THE PAIRWISE ADDITIVE FORCE EXERTED ON A PARTICLE Ð BY A PARTICLE Ð INCLUDES CONTRIBUTIONS FROM ALL THE BEADS WITHIN THE CUT-OFF RADIUS R!, WHICH INTRODUCES A CHARACTERISTIC LENGTH SCALE.3 THE TOTAL FORCE ACTING BETWEEN THE NON-BONDED BEADS ENCOMPASSES REPULSIVE CONSERVATIVE FORCE, Ð "# $ , DISSIPATIVE Ð "# % , AND RANDOM Ð "# & FORCES.3 WE CHOSE THE CONSERVATIVE FORCE AS Ð "# $ = A"#(1 Â R"#/Ð '-Ð "# FOR R"# < R!, , WHERE A"# IS THE MAXIMUM REPULSION BETWEEN THE I AND J BEADS, R"# = 5Ð «"#5 IS THE DISTANCE BETWEEN THEM, Ð «"# = Ð «" Â Ð «#, AND Ð "# = Ð «"#/R"# . THE REPULSION COEFFICIENT IN DPD IS RELATED TO THE FLORY-HUGGINS INTERACTION PARAMETER, Ð () , AS3 Ð () = Ð (( + 3.27Ð () , WHERE Ð (( IS THE REPULSION COEFFICIENT BETWEEN THE SAME TYPE OF BEADS. MOST COMMONLY, THE VALUE OF Ð (( IS DERIVED BASED ON THE DEGREE OF COARSE-GRAINING5, HOWEVER VARIOUS PARAMETRIZATION APPROACHES CAN BE UTILIZED11-13. THE INTERACTIONS BETWEEN THE BONDED BEADS INCLUDE FORCES DUE TO THE HARMONIC Ð * = Ð ¾*(Ð () Â Ð +-, AND ANGLE Ð - = Ð ¾-(Ð (). Â Ð +-, POTENTIALS ACTING BETWEEN THESE BEADS. HEREIN, Ð + IS AN EQUILIBRIUM BOND LENGTH, Ð ¾* IS A SPRING CONSTANT, Ð (). IS AN ANGLE BETWEEN THE TWO CONSECUTIVE BONDS BETWEEN THE Ð Ð AND Ð Ð PAIRS OF BEADS, AND Ð ¾- DEFINES THE RIGIDITY OF THE POLYMER CHAIN. NOTABLY, THE SOFT CONSERVATIVE FORCE IN DPD INTRODUCED ABOVE DOES NOT PREVENT POLYMER CHAINS CROSSING. THIS IS A KNOWN LIMITATION OF THE STANDARD DPD APPROACH. TO EFFECTIVELY MINIMIZE TOPOLOGICAL VIOLATIONS, IN THE STUDIES PROPOSED BELOW WE WILL USE MODIFIED SEGMENTAL REPULSIVE POTENTIAL (MSRP) 14 FORMULATION OF DPD. WITHIN THE MSRP DPD FRAMEWORK, THE PSEUDO BEADS ARE INTRODUCED AT THE CENTER OF EACH BOND FOR ALL THE BONDS, THESE BEADS INTERACT VIA AN ADDITIONAL REPULSIVE FORCE APPLIED BETWEEN THEIR CENTERS IF THE DISTANCE BETWEEN THESE CENTERS IS BELOW THE CUTOFF DISTANCE. THE MSRP DPD APPROACH CAPTURES THE EFFECTS OF ENTANGLEMENTS, WHICH IS CRITICALLY IMPORTANT TO PREDICT PROPERTIES OF RESULTING MATERIALS. HOWEVER THE MSRP DPD APPROACH WAS ORIGINALLY 3 DEVELOPED FOR POLYMERS WITH FIXED TOPOLOGY, I.E. POLYMERIC SYSTEMS WITHOUT CHEMICAL REACTIONS. FOR MODELING CHEMICAL REACTIONS THE ADDITIONAL REPULSION BETWEEN THE CENTERS OF THE BONDS NEEDS TO BE SWITCHED ON UPON BOND FORMATION AND OFF UPON BOND BREAKING. KUKSENOK GROUP RECENTLY INCORPORATED THIS ABILITY INTO THE MSRP FRAMEWORK AND IMPLEMENTED IT AS PART OF THE LAMMPS SIMULATION SOFTWARE15-17. SPECIFICALLY, IN ORDER TO SWITCH THE EXTRA REPULSION ON AND OFF, WE INTRODUCED THE ABILITY TO INSERT AND DELETE PSEUDO BEADS VIA THE PAIR STYLE SRP/REACT COMMAND IN LAMMPS 18. THE MSRP DPD APPROACH INTRODUCED ABOVE ENSURES THAT THE UNPHYSICAL BONDS CROSSING IS MINIMIZED FOR ALL THE BONDS IN THE SYSTEM INCLUDING THE NEW BONDS FORMED. WE USED THIS MODIFIED MSRP DPD FRAMEWORK TO MODEL BOND BREAKING AND EROSION (WHICH IS DEFINED AS THE PROCESS OF MASS LOSS DURING THE DEGRADATION) IN TETRA-PEG NETWORKS19 (FIG. 1 A-D). FURTHER, WE ADAPTED MSRP DPD TO MODEL HYDROSILILALILATION REACTION ALONG WITH THE PHASE SEPARATION IN THE BINARY POLYMER BLENDS INCORPORATING POLYHYDROMETHYLSILOXANE (PHMS) AND VINYL-TERMINATED POLYDIMETHYLSILOXANE (V-PDMS) AND IN THE TERNARY BLENDS, WHICH IN ADDITION TO PHMS AND V-PDMS LINEAR CHAINS ALSO INCORPORATE SECOND SACRIFICIAL NON-REACTIVE COMPONENT20. THE FOLLOWING LINEAR CHAINS WERE CONSIDERED AS AN ADDITIONAL NON-REACTIVE SACRIFICIAL COMPONENT: METHYL-TERMINATED PDMS (M-PDMS), POLY(METHYL METHACRYLATE) (PMMA), AND POLYACRYLONITRILE (PAN). TO QUANTITATIVELY CHARACTERIZE EVOLUTION IN THE BINARY AND TERNARY REACTIVE BLENDS, THE TIME EVOLUTION OF THE CHARACTERISTIC LENGTH SCALE WITHIN THE SYSTEM REPRESENTING THE SIZE OF THE SACRIFICIAL DOMAINS, AS WELL AS FRACTION OF VINYL GROUPS OF V-PDMS THAT REMAIN UNREACTED AT A GIVEN TIME INSTANT, WERE CHARACTERIZED AS A FUNCTION OF TIME (FIG. 1 E-F). IN ADDITION, KUKSENOK AND COLLABORATORS PREVIOUSLY UTILIZED DPD APPROACH TO MODEL GELATION VIA ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)21, FREE RADICAL POLYMERIZATION (FRP)22, AND INIFERTER-MEDIATED PHOTO-GROWTH OF HYDROGELS23, 24. FIG. 1 (A-D) DEGRADATION AND EROSION OF TETRA-PEG NETWORK19. (A) FRAGMET OF INITIAL NETWORK TOPOLOGY, THE INSET SHOWS A ZOOMED-IN VIEW HIGHLIGHTING DEGRADABLE BOND. PEG BEADS ARE SHOWN IN CYAN, THE CENTERS OF TETRA-PEG PRECURSORS AND END FUNCTIONALITIES ARE SHOWN IN YELLOW, RED AND BLUE, RESPECTIVELY. SNAPSHOTS OF (A) AN EQUILIBRATED HYDROGEL FILM IN WATER AND (B-D) DEGRADING FILM; THE BEADS REPRESENTING WATER ARE HIDDEN FOR CLARITY. (E-F) HYDROSILILALILATION REACTION IN THE BLENDS OF PHMS AND V-PDMS20. SNAPSHOTS OF BLEND MORPHOLOGY AT TIMES INDICATED ON THE ARROW, (F) TIME EVOLUTION OF THE CHARACTERISTIC LENGTH SCALE, Ð (Ð ¡) (LEFT AXIS) AND THE NUMBER OF VINYL GROUPS IN THE SYSTEM NORMALIZED BY THE INITIAL NUMBER OF THESE GROUPS, Ð /(Ð ¡)/Ð /(0) (RIGHT AXIS). THE TIME INSTANCES CORRESPONDING TO THE SNAPSHOTS IN (E) ARE MARKED BY THE OPEN CIRCLES. THE INSET IN (F) SHOWS EVOLUTION AT EARLY TIMES. MODELING POLYMER SYNTHESIS AND CONTROLLED DECONSTRUCTION AND RECONSTRUCTION PROCESSES. THE FOLLOWING
Clemson University
Project Grant 2317582
$100.1k 11/9/23