Change search
ReferencesLink to record
Permanent link

Direct link
Suspension polymerization of thermally expandable core/shell particles
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-8348-2273
2006 (English)In: Polymer, ISSN 0032-3861, E-ISSN 1873-2291, Vol. 47, no 10, 3315-3324 p.Article in journal (Refereed) Published
Abstract [en]

Acrylonitrile (AN)-methacrylonitrile (MAN) copolymer particles with a core/shell structure were prepared by suspension polymerization. The particles were about 10–20 μm in diameter and had a hollow core containing an inert hydrocarbon. The influence of the monomer feed ratio and the polymerization temperature on the particle morphology was studied. One purpose of this study was to determine the boundaries for achieving a core/shell structure with the polymer encapsulating the hydrocarbon. When polymerizing at 62 °C, it was found that an initial AN/MAN feed ratio (fAN) between 0.15 and 0.9 results in core/shell particles with encapsulated hydrocarbon. fAN lower than 0.15 yielded solid particles with no hydrocarbon encapsulated while fAN higher than 0.9 yielded particles built up entirely from agglomerates of smaller primary particles. In contrast, when polymerizing at 80 °C, a much narrower span of fAN (0.5–0.85) yielded particles with hydrocarbon encapsulated. The influence on monomer conversion and the molecular weight of the polymer was also studied.

Place, publisher, year, edition, pages
Amsterdam: Elsevier Ltd. , 2006. Vol. 47, no 10, 3315-3324 p.
Keyword [en]
Suspension polymerization; Core/shell morphology; Encapsulation
National Category
Polymer Chemistry
URN: urn:nbn:se:kth:diva-11975DOI: 10.1016/j.polymer.2006.03.013ISI: 000237859400006ScopusID: 2-s2.0-33646162178OAI: diva2:291713
QC 20101001Available from: 2010-02-03 Created: 2010-02-03 Last updated: 2010-10-01Bibliographically approved
In thesis
1. Thermally Expandable Microspheres Prepared via Suspension Polymerization - Synthesis, Characterization, and Application
Open this publication in new window or tab >>Thermally Expandable Microspheres Prepared via Suspension Polymerization - Synthesis, Characterization, and Application
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Thermally expandable microspheres are polymeric core/shell particles in which a volatile hydrocarbon is encapsulated by a thermoplastic shell. When these microspheres are heated, they expand and increase their volume dramatically. This volume increase is retained upon cooling, leading to a density reduction from around 1100 kg m-3 to about 30 kg m-3. Since the development in the early 1970´s, microspheres have been used extensively by the industry as a foaming agent or light weight filler.

In this thesis, microspheres with a poly(acrylonitrile-co-methacrylonitrile) shell have been synthesized through free radical suspension polymerization. The microspheres have been characterized with respect to particle morphology and expansion properties in order to deepen the understanding of the microspheres.

It was found that the monomer feed ratio and the polymerization temperature are very important parameters with respect to the expansion properties. Excellent expansion could only be accomplished when polymerizing at 62 °C, with the acrylonitrile feed, fAN, being around 60 mol%, even though core/shell microspheres are formed over a much wider range of fAN. Furthermore, no expansion was achieved when polymerizing at 80 °C, even though no noticeable differences were found, compared to the corresponding sample polymerized at 62 °C.

It was also shown that the expansion properties can be modified by replacing the encapsulated hydrocarbon by another hydrocarbon with a different boiling point. Not only is the boiling point important, the structure of the hydrocarbon is also important. Isooctane which is highly branched was found to give superior expansion compared to linear or cyclic hydrocarbons having a similar boiling point.

Crosslinking of the polymer shell has proven to be very important for the expansion properties. Both the amount and the structure of the crosslinker are important parameters. Especially the maximum expansion can be improved by the crosslinking of the polymer shell. This originates in an increase in the shape persistence of the expanded microspheres at elevated temperatures. By the combination of crosslinkers that are incorporated separately into the polymer shell, the onset temperature of expansion can be increased significantly.

Finally, the surface of microspheres has been modified by grafting poly(glycidyl methacrylate) from the surface by ARGET ATRP. Given that the reaction conditions are appropriate, such modifications can be performed with only limited effects on the expansion properties of the microspheres.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 54 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2010:4
Thermally expandable microspheres
National Category
Polymer Chemistry
urn:nbn:se:kth:diva-11981 (URN)978-91-7415-542-6 (ISBN)
Public defence
2010-02-26, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Available from: 2010-02-04 Created: 2010-02-03 Last updated: 2010-04-28

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Jonsson, MagnusMalmström, Eva
By organisation
Fibre and Polymer Technology
In the same journal
Polymer Chemistry

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 185 hits
ReferencesLink to record
Permanent link

Direct link