Effect of Low-Concentration Polymers on Crystal Growth in Molecular Glasses: A Controlling Role for Polymer Segmental Mobility Relative to Host Dynamics
| Autor: | Ye Sun, Chengbin Huang, Lian Yu, Ting Cai, C. Travis Powell |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
chemistry.chemical_classification
Materials science Molecular mass Doping Crystal growth 02 engineering and technology Polymer Degree of polymerization 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films law.invention Crystal Chemical engineering chemistry law Polymer chemistry Materials Chemistry Physical and Theoretical Chemistry Crystallization 0210 nano-technology Glass transition |
| Zdroj: | The Journal of Physical Chemistry B. 121:1963-1971 |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/acs.jpcb.6b11816 |
| Popis: | Low-concentration polymers can strongly influence crystal growth in small-molecule glasses, a phenomenon important for improving physical stability against crystallization. We measured the velocity of crystal growth in two molecular glasses, nifedipine (NIF) and o-terphenyl (OTP), each doped with four or five different polymers. For each polymer, the concentration was fixed at 1 wt % and a wide range of molecular weights was tested. We find that a polymer additive can strongly alter the rate of crystal growth, from a 10-fold reduction to a 10-fold increase. For a given polymer, increasing molecular weight slows down crystal growth and the effect saturates around DP = 100, where DP is the degree of polymerization. For all the systems studied, the polymer effect on crystal growth rate forms a master curve in the variable (Tg,polymer – Tg,host)/Tcryst, where Tg is the glass transition temperature and Tcryst is the crystallization temperature. These results support the view that a polymer’s effect on crystal ... |
| Databáze: | OpenAIRE |
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