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Effect of TiO2 Formation on the Free Volume Properties of Electrospun PMMA Nanohybrids

Zhang, Junhua; Yang, Mingshu and Maurer, Frans LU (2011) In Macromolecules 44(14). p.5711-5721
Abstract
Positron annihilation lifetime spectroscopy (PALS) has been performed on a series of PMMA nanohybrids containing nanometric TiO2, which were produced by means of different preparation methods, i.e., melt mixing, electrospinning combined with solution mixing, or in-situ sol gel growth methods, to study the effect of filler content and constituents on the free volume properties. The PMMA nanocomposites containing titania precursor or in-situformed TiO2 additives exhibit altered free volume properties compared to adding commercial TiO2 P25 fillers. The orthopositronium (o-Ps) lifetime (tau(3)) (free volume cavity size) was constant with composition in P25/PMMA nanohybrids due to the absence of interfacial interaction. However, in TiO2... (More)
Positron annihilation lifetime spectroscopy (PALS) has been performed on a series of PMMA nanohybrids containing nanometric TiO2, which were produced by means of different preparation methods, i.e., melt mixing, electrospinning combined with solution mixing, or in-situ sol gel growth methods, to study the effect of filler content and constituents on the free volume properties. The PMMA nanocomposites containing titania precursor or in-situformed TiO2 additives exhibit altered free volume properties compared to adding commercial TiO2 P25 fillers. The orthopositronium (o-Ps) lifetime (tau(3)) (free volume cavity size) was constant with composition in P25/PMMA nanohybrids due to the absence of interfacial interaction. However, in TiO2 precursor/PMMA composite fibers the free volume cavity size decreased substantially with hydroxyl group concentration and recovered after hydrothermal treatment. Additionally, a strong correlation between the glass transition temperature and the o-Ps lifetime in the nanohybrids was observed. These effects are caused by the hydrogen-bonding interaction between hydroxyl groups in the inorganic phase and carbonyl groups in the PMMA matrix, which concentration is dependent on the hydrothermal treatment, leading to differences in the packing of the polymer chains and a changed polymer segmental flexibility. The results also show a clear linear decrease in the o-Ps yield (I-3) with increasing P25 content of the composites. A dominant inhibition effect was observed in the TiO2 precursor/PMMA systems, caused by inhibition of positronium formation by the hydroxyl group in the titania precursor. In addition to the pronounced negative deviations of the o-Ps intensity with the concentration of hydroxyl groups in in-situ TiO2/PMMA nanohybrid fibers, a stronger inhibition efficiency of hydroxyl groups was observed than in the precursor/PMMA nanocomposite fibers. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Macromolecules
volume
44
issue
14
pages
5711 - 5721
publisher
The American Chemical Society
external identifiers
  • wos:000292850100022
  • scopus:79960491677
ISSN
0024-9297
DOI
10.1021/ma201004b
language
English
LU publication?
yes
id
56188735-77ae-476d-9582-28324ecbf7ca (old id 2065428)
date added to LUP
2011-08-29 16:52:41
date last changed
2017-11-19 03:14:21
@article{56188735-77ae-476d-9582-28324ecbf7ca,
  abstract     = {Positron annihilation lifetime spectroscopy (PALS) has been performed on a series of PMMA nanohybrids containing nanometric TiO2, which were produced by means of different preparation methods, i.e., melt mixing, electrospinning combined with solution mixing, or in-situ sol gel growth methods, to study the effect of filler content and constituents on the free volume properties. The PMMA nanocomposites containing titania precursor or in-situformed TiO2 additives exhibit altered free volume properties compared to adding commercial TiO2 P25 fillers. The orthopositronium (o-Ps) lifetime (tau(3)) (free volume cavity size) was constant with composition in P25/PMMA nanohybrids due to the absence of interfacial interaction. However, in TiO2 precursor/PMMA composite fibers the free volume cavity size decreased substantially with hydroxyl group concentration and recovered after hydrothermal treatment. Additionally, a strong correlation between the glass transition temperature and the o-Ps lifetime in the nanohybrids was observed. These effects are caused by the hydrogen-bonding interaction between hydroxyl groups in the inorganic phase and carbonyl groups in the PMMA matrix, which concentration is dependent on the hydrothermal treatment, leading to differences in the packing of the polymer chains and a changed polymer segmental flexibility. The results also show a clear linear decrease in the o-Ps yield (I-3) with increasing P25 content of the composites. A dominant inhibition effect was observed in the TiO2 precursor/PMMA systems, caused by inhibition of positronium formation by the hydroxyl group in the titania precursor. In addition to the pronounced negative deviations of the o-Ps intensity with the concentration of hydroxyl groups in in-situ TiO2/PMMA nanohybrid fibers, a stronger inhibition efficiency of hydroxyl groups was observed than in the precursor/PMMA nanocomposite fibers.},
  author       = {Zhang, Junhua and Yang, Mingshu and Maurer, Frans},
  issn         = {0024-9297},
  language     = {eng},
  number       = {14},
  pages        = {5711--5721},
  publisher    = {The American Chemical Society},
  series       = {Macromolecules},
  title        = {Effect of TiO2 Formation on the Free Volume Properties of Electrospun PMMA Nanohybrids},
  url          = {http://dx.doi.org/10.1021/ma201004b},
  volume       = {44},
  year         = {2011},
}