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Computationally guided synthesis of carbon coated mesoporous silica materials

Evidence and attribution

Authority of statements

Summaries follow Carbon 221, 118891 (DOI in front matter). Percentages and temperature programs are quoted from the abstract/article and should be checked against tables.

Summary

The article builds a computationally guided picture of mesoporous silica formation and subsequent high-temperature carbonization of hydrocarbon precursors confined in pores, motivated by biomedical durability scenarios where carbon coatings can heal or protect silica frameworks. The workflow combines classical MD of Pluronic L64 self-assembly in water (non-reactive) with bond-boosted ReaxFF MD for silicic acid condensation to mimic mesostructure development, then simulates pyrolysis of several hydrocarbon models (polyethylene, lignite, sucrose, and a PET-like structure) inside silica confinement at 2200–2600 K, monitoring six-membered ring formation and gas evolution.

Methods

Micelle self-assembly (classical MD)

Pluronic L64 + water; H-bond statistics between hydrophilic blocks and water.

Silica polymerization (ReaxFF + bond boost)

ReaxFF with bond boosting at 300 K; 1500 K unboosted segments; Si(OH)\(_4\) addition protocols per Carbon 221 118891.

In-pore carbonization (ReaxFF, high T)

2200–2600 K reactive runs on PE, lignite, sucrose, PET-like precursors—sp², H\(_2\), turbostratic signatures.

MD application (ReaxFF + bond boost, classical micelles). Molecular dynamics in LAMMPS: NVT/NPT-segmented periodic supercells; classical force field (non-reactive block) for Pluronic L64+water as named in the article; ReaxFF+bond boost for silicic acid condensation at 300 K; unboosted 1500 K NVT; NVT heating to 2200–2600 K for confined pyrolysis. Time step (fs), Nosé–Hoover thermostat, ps/ns stages—Carbon 221; N/A—external E-field; bond boost covers rare reactive events; Hydrostatic pressure N/A unless a NPT segment is used—Methods in papers/Dagupta_Mao_mesopores_Carbon_2024.pdf. System size and Si/O/C/H atom counts: article.

Findings

Outcomes and mechanisms (micelle → silica → pyrolysis). In the classical Pluronic+water block, ~80% of H-bonds link hydrophilic micelle blocks to water, supporting the self-assembly picture used to template confinement. In the ReaxFF silicic-acid condensation block, >60% of the addition sequences tested give periodic mesoporous-like order; 1500 K unboosted runs double the polymerization rate relative to 300 K boosted runs, highlighting bond-boost artifacts that must be read next to the unboosted reference segments. In the high-T pyrolysis block, polyethylene and high-rank lignite carbon precursors most readily form turbostratic graphene-like carbon in pores; sucrose gives the least planar sp² content in the comparison shown. A PET-like trajectory produces a tar that coats pore openings and can block silicic acid ingress—a failure mode for continued condensation.

Comparisons, sensitivity, limitations (as presented). The work compares O/C/H-rich feeds across PE, lignite, sucrose, and PET-like cases; sensitivity to temperature spans room-temperature-scale condensation through 2200–2600 K pyrolysis windows. Open questions include how laboratory carbonization maps to these extreme-T toy models—see ## Limitations. Corpus honesty: a proof-PDF sibling exists as [[2024dagupta-venue-paper]]; cite paper:2024dasgupta-carbon-221-2-computationally-guided for the version-of-record DOI 10.1016/j.carbon.2024.118891.

Limitations

Bond boosting accelerates rare events—validate against unboosted segments and QM where provided. Pyrolysis temperatures are extreme relative to laboratory carbonization; qualitative mechanism insight is the primary output.

The multi-precursor comparison (PE, lignite, sucrose, PET-like) is the paper’s practical hook for materials design: different O/C/H compositions yield different H₂ release, sp² development, and tar behavior inside pores, which matters when coatings must block further silicic acid transport versus allowing it.

Relevance to group

van Duin-affiliated work combining ReaxFF silica polycondensation with confined pyrolysis, aligned with biomaterials-adjacent carbon–oxide processing themes.

The Pluronic self-assembly stage (classical MD) and the ReaxFF silica stage are intentionally multiscale: agents should not attribute mesopore metrics from the classical block to the reactive block without checking which section generated which structural claim.

Citations and evidence anchors

MAS / retrieval

Group-affiliated paper: with keyword:polymer + keyword:silica-silicate supports biomaterials/mesopore queries that span classical self-assembly and ReaxFF condensation.