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dc.contributor.authorWen, Xiangning
dc.contributor.authorSu, Yunlan
dc.contributor.authorShui, Yudan
dc.contributor.authorZhao, Weiwei
dc.contributor.authorMüller Sánchez, Alejandro Jesús
dc.contributor.authorWang, Dujin
dc.date.accessioned2019-06-03T15:49:17Z
dc.date.available2019-06-03T15:49:17Z
dc.date.issued2019-02-06
dc.identifier.citationMacromolecules 52(4) : 1505−1516 (2019)es_ES
dc.identifier.issn0024-9297
dc.identifier.urihttp://hdl.handle.net/10810/33074
dc.description.abstractThe interfacial interactions of polymer-nanoparticles have dramatical effects on the crystallization behavior of grafted polymers. In this study, methoxy polyethylene glycol (MPEG) (molecular weights 750, 2000 and 4000 g mol−1) was grafted onto amino-modified nanosized silica (SiO2-NH2) by the “grafting to” method. The effects of the grafting density and molecular weight on the confined crystallization of grafted MPEG (MPEG-g-SiO2) were systematically investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and wide-angle X-ray scattering (WAXS). It was found that confinement effects are stronger when lower molecular weights of grafted MPEG are employed. These grafted MPEG chains are more difficult to stretch out on SiO2-NH2 surfaces than when they are free in the bulk polymer. Both crystallization temperature (Tc) and crystallinity of grafted MPEG chains decrease with reductions of grafting density. Additionally, covalent bonding effects and interfacial interaction confinement effects are strengthened by the decrease in grafting density, leading to an increase in decomposition temperature and to the disappearance of the self-nucleation Domain (i.e., Domain II), when self-nucleation experiments are performed by DSC. Overall isothermal crystallization kinetics was studied by DSC and the results were analyzed with the Avrami equation. An Avrami index of n≈3 was obtained for neat MPEG (indicating that instantaneous spherulites are formed). However, in the case of MPEG-g-SiO2 with the lowest grafting density, the Avrami index of (n) was less than 1 (first order kinetics or lower), indicating that nucleation is the determining factor of the overall crystallization kinetics, a signature for confined crystallization. At the same time, the crystallization from the melt for this MPEG-g-SiO2 with the lowest grafting density occurs at Tc ≈-30 ºC, a temperature close to the glass transition temperature (Tg) of MPEG, indicating that this confined MPEG crystallizes from homogeneous nuclei.es_ES
dc.description.sponsorshipThis project was supported by the National Natural Science Foundation of China (21574141) and the Ministry of Science and Technology of China (2017YFE0117800). The authors gratefully acknowledge the funding of project BIODEST, Research and Innovation Staff Exchange (RISE) H2020-MSCA-RISE-2017-778092. The authors thank beamline BL16B1 (Shanghai Synchrotron Radiation Facility) for providing the beam time and helps during experiments.es_ES
dc.language.isoenges_ES
dc.publisherAmerican Chemical Societyes_ES
dc.relationinfo:eu-repo/grantAgreement/EC/H2020/778092es_ES
dc.rightsinfo:eu-repo/semantics/openAccesses_ES
dc.subjectconfined crystallizationes_ES
dc.subjectStöber silicaes_ES
dc.subjectnanoparticleses_ES
dc.subjectpoly(ethylene glycol)es_ES
dc.titleCorrelation between Grafting Density and Confined Crystallization Behavior of Polyethylene Glycol Grafted to Silicaes_ES
dc.title.alternativeCorrelation between Grafting Density and Confined Crystallization Behavior of Poly(ethylene glycol) Grafted to Silicaes_ES
dc.typeinfo:eu-repo/semantics/articlees_ES
dc.rights.holderCopyright © 2019 American Chemical Societyes_ES
dc.relation.publisherversionhttps://pubs.acs.org/doi/10.1021/acs.macromol.8b02007es_ES
dc.identifier.doi10.1021/acs.macromol.8b02007
dc.contributor.funderEuropean Comission
dc.departamentoesCiencia y tecnología de polímeroses_ES
dc.departamentoeuPolimeroen zientzia eta teknologiaes_ES


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