Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602.
Langmuir. 2011 Sep 6;27(17):10538-47. doi: 10.1021/la202110w. Epub 2011 Jul 29.
We report the formation and characterization of stable dispersions of hybrid nanoparticles in solution formed via stereocomplexation of enantiomeric poly(lactide) hybrid star polymers. The hybrid starlike polymers, having polyhedral oligomeric silsesquioxane (POSS) nanocages as the core and either poly(L-lactide) (PLLA) or poly(D-lactide) (PDLA) as the arms, are synthesized via ring-opening polymerization of lactide using octafunctional POSS as the macroinitiator. In the solid state, differential scanning calorimetry and wide-angle X-ray scattering measurements confirmed the formation of the stereocomplex in the mixture of POSS-star-PLLA and POSS-star-PDLA (50:50, wt %). In a solution of the same mixture in tetrahydrofuran (THF), sterocomplexation leads to formation of hybrid nanaoparticles. Detailed accounts of the nanoparticle formation and influence of aging and concentration have been presented. It was observed that at low concentration the stereocomplexed nanaoparticles remain stable over 45 days and are not sensitive to dilution, suggesting the formation of a stable hybrid nanoparticle dispersion in solution. In contrast, the aggregates of the individual POSS-star-PLLA or POSS-star-PDLA in THF, formed via weak solvophobic interactions, tended to disintegrate into smaller aggregates on dilution. Exploiting the PLLA-PDLA stereocomplexation with an appropriate molecular design can be a versatile route to develop stable organic/inorganic hybrid nanoparticle dispersions.
我们报告了通过对映异构聚(丙交酯)杂化星型聚合物的立体复合物形成稳定分散体的形成和特性。杂化星型聚合物具有多面体低聚倍半硅氧烷(POSS)纳米笼作为核,聚(L-丙交酯)(PLLA)或聚(D-丙交酯)(PDLA)作为臂,通过使用八官能 POSS 作为大分子引发剂开环聚合丙交酯来合成。在固态下,差示扫描量热法和广角 X 射线散射测量证实了 POSS-星-PLLA 和 POSS-星-PDLA(50:50,wt%)混合物中立体复合物的形成。在相同混合物的四氢呋喃(THF)溶液中,立体复合物化导致杂化纳米粒子的形成。详细介绍了纳米粒子形成以及老化和浓度的影响。观察到,在低浓度下,立体复合物纳米粒子在 45 天内保持稳定,并且对稀释不敏感,表明在溶液中形成了稳定的杂化纳米粒子分散体。相比之下,通过弱溶剂化相互作用在 THF 中形成的单独 POSS-星-PLLA 或 POSS-星-PDLA 的聚集体在稀释时容易分解成较小的聚集体。利用 PLLA-PDLA 立体复合物化进行适当的分子设计可以成为开发稳定的有机/无机杂化纳米粒子分散体的通用途径。
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