# Evidence: surface-enhanced crystal growth

Parent: surface crystallization · class: kinetics · names merged here: surface crystal growth; surface-enhanced crystal growth

4 papers measured or used it, 0 only mentioned it (of 207 kept papers). Papers in year order; each section heading ends with the paper's category / subcategory. Generated by tools/build_evidence.py from registry/concepts.csv and the cards; do not edit.

## 2010 Rumondor — Effects of Moisture on the Growth Rate of Felodipine Crystals in the Presence and Absence of Polymers · Solid state stability / Physical stability

[2010-rumondor-moisture-felodipine-crystal-growth-pvp-hpmcas](../../../cards/2010-rumondor-moisture-felodipine-crystal-growth-pvp-hpmcas/paper.html) · Solid state stability / Physical stability · used · as: surface crystal growth

| id | kind | content | locator |
|---|---|---|---|
| R12 | record, cited | surface versus bulk crystal growth; diffusion-viscosity decoupling — refs 24-28 — crystal growth rates at the surface much faster than in the bulk (refs 26-28); decoupling between drug diffusion and viscosity reported for a number of compounds (refs 24, 25) | p.751 |
| C28 | claim, mechanism, authors: "Possible explanations"; "could include"; "likely reflect" | Possible reasons for growth faster than mobility predicts are decoupling between drug diffusion and viscosity, or growth at the surface of the uncovered thin films, where growth is much faster than in the bulk [rests on: R12] | p.751 |
| C29 | claim, caveat, authors: "may not be reasonable" | It may not be reasonable to correlate bulk mobility estimates derived from Tg with surface growth [rests on: R12] | p.751 |
| C30 | claim, generalisation, authors: "likely" | Because crystallization likely starts at the surface, the thin uncovered film preparation used here is highly relevant [rests on: argument only] | p.751 |

## 2013 Kestur — Evaluation of the crystal growth rate of felodipine polymorphs in the presence and absence of additives as a function of temperature · Solid state stability / Physical stability

[2013-kestur-felodipine-polymorph-crystal-growth-pvp-additives](../../../cards/2013-kestur-felodipine-polymorph-crystal-growth-pvp-additives/paper.html) · Solid state stability / Physical stability · measured · as: surface-enhanced crystal growth

| id | kind | content | locator |
|---|---|---|---|
| R8 | record, measured and cited | crystal growth rate (m/s; mean of three; error bars standard deviation) vs temperature, pure felodipine — form I at the free surface (P2) and in the bulk (P3); form II in the bulk; form II above 60 °C previously reported (caption: ref 9; methods: ref 8) — sub-table below | Fig. 2, p.16 |
| R9 | record, measured | form I surface vs bulk growth, values stated in the text — pure felodipine (R8) — lowering the temperature from 100 °C (Tg +56.5 °C) to 18 °C (Tg -25.5 °C) lowers surface and bulk rates by approximately 3-4 orders of magnitude (R8.m to R8.a); no difference between surface and bulk above 70 °C (results p.8), indistinguishable at 70-90 °C (discussion p.10); surface faster than bulk below 65 °C; surface approximately 6 times faster than bulk at 18 °C (results p.8); approximately 5-6 times faster closer to and below Tg (discussion p.9) | p.8-10; Fig. 2 |
| R14 | record, measured | features of growth with 3% PVP, stated in the text — R13 — peak growth rate at 100 °C (form I) and 105 °C (form II), where the rate with PVP was similar to that of pure felodipine; form I rate about 3-4 orders of magnitude lower at 50 °C; uncovered surface crystals grow 1-1.5 orders of magnitude faster than bulk crystals; below 50 °C, in the region of the felodipine Tg (40-45 °C), a sudden jump for surface and bulk form I; form II declines smoothly; below 60 °C form II rates too slow to measure in a reasonable time. Figure: form I rises between 45 and 40 °C, surface ≈5.9×10⁻¹⁰ to ≈3.3×10⁻⁹ m/s, bulk ≈6.8×10⁻¹¹ to ≈3.2×10⁻¹⁰ m/s (R13.c, R13.b) | p.9; Fig. 3 |
| C2 | claim, conclusion, authors: abstract: asserted; results: "This shows"; discussion: "clearly show" | Form I grows faster at the free surface than in the bulk below 65 °C, with no difference above 70 °C; the felodipine growth rate is enhanced at the free surface [rests on: R8, R9] | p.2, p.8, p.9-10 |
| C15 | claim, conclusion, authors: asserted ("thus") | Felodipine is another pharmaceutical system with surface-enhanced growth close to and below Tg [rests on: R8, R9; cited: R17] | p.10 |

## 2013 Kestur — Influence of particle size on the crystallization kinetics of amorphous felodipine powders · Solid state stability / Physical stability

[2013-kestur-particle-size-crystallization-amorphous-felodipine-pvp](../../../cards/2013-kestur-particle-size-crystallization-amorphous-felodipine-pvp/paper.html) · Solid state stability / Physical stability · measured · as: surface-enhanced crystal growth

| id | kind | content | locator |
|---|---|---|---|
| R12 | record, derived (E2) | linear growth rate of form I at 30 °C, 0% RH — free surface versus bulk (P8); pure felodipine and 3% PVP — sub-table below; text: ≈6 times faster at the surface without polymer, ≈23 times with PVP; surface rate 2 times and bulk rate a factor of 7 faster without PVP than with PVP | Table 1, p.202; text p.200, p.202 |
| C13 | claim, conclusion, authors: asserted | Felodipine crystals grow faster at the free surface than in the bulk, about 6 times without polymer and 23 times with PVP [rests on: R12] | p.197, p.200 |
| C32 | claim, conclusion, authors: asserted | With PVP the surface growth rate is about 23 times the bulk rate; the higher ratio than for pure felodipine comes mainly from PVP slowing bulk growth, PVP not reducing surface growth by a large extent [rests on: R12] | p.202 |
| C33 | claim, mechanism, authors: discussion: "suggesting", "probably"; abstract and conclusions: asserted ("was attributed") | The average ratio of early to late crystallization slope (14) is reasonably similar to the surface/bulk growth ratio with PVP (about 23), so the rapid initial crystallization is probably due to the much faster surface growth; abstract and conclusions state this attribution without hedge [rests on: R12, R14] | p.197, p.202, p.203 |
| C23 | claim, prior hypothesis, authors: asserted | Surface-enhanced crystal growth, reported for indomethacin, nifedipine and griseofulvin, is most pronounced below Tg and has been attributed to enhanced molecular mobility at the surface [rests on: cited: refs 11, 12, 14, 27-29] | p.201 |

## 2014 Trasi — Factors Influencing Crystal Growth Rates from Undercooled Liquids of Pharmaceutical Compounds · Solid state stability / Crystallization tendency

[2014-trasi-crystal-growth-rates-undercooled-pharmaceutical-liquids](../../../cards/2014-trasi-crystal-growth-rates-undercooled-pharmaceutical-liquids/paper.html) · Solid state stability / Crystallization tendency · measured · as: surface crystal growth

| id | kind | content | locator |
|---|---|---|---|
| R4 | record, measured | surface radial growth rate versus T/Tg — 14 compounds, top coverslip removed (P2), near Tg — sub-table below | Fig. 2a, p.9976 |
| C8 | claim, conclusion, authors: asserted ("We note") | The order of surface growth rates does not necessarily match the bulk order (felodipine grows faster than carbamazepine and nilutamide at the surface but slower than nilutamide at all temperatures and than carbamazepine at higher temperatures in the bulk), although the slowest surface grower, loratadine, is also slow in the bulk and the faster surface growers, piroxicam and acetaminophen, are also fast in the bulk [rests on: R4, R5] | p.9976-9977 |
| C4 | claim, prior hypothesis, authors: "has been shown"; "is thought to be" | Surface crystal growth is generally faster than bulk growth, particularly at low temperatures where the material does not flow, and is thought to reflect higher surface mobility near or below Tg; the relation between surface and bulk rates has not been widely explored [rests on: cited: refs 13, 19] | p.9976 |