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學生：李明真
指導教授：陳澄河 教授
日期：2015/12/15
Outline
Experimental
Results and discussion
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Outline
Experimental
2
Introduction(1/3)
1.Hydroxypropylcellulose (HPC) is a kind of hydroxyl-substituted
cellulose derivatives and has been used in pharmaceutical,
adhesives, food, cosmetic and controlled drug release.
Nowadays, its thermo-sensitive property has caused
scientists' interest.
HPC
(羥丙基纖維素)
2. The dipole moment of the propylene oxide moieties may be decreased
in water and the hydrophobic interaction of HPC is so strong that the
phase separation of HPC aqueous solution occurs.
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Introduction(2/3)
3.Interpolymer hydrogen bonding between HPC and PAA led to a
dramatic decrease of phase transition .More interestingly, with the help
of hydrogen bonding interaction between AA, PAA and HPC, HPC
chains dehydrated to form nanocolloids around room temperature and
then PAA chains attached on the surface of HPC nanocolloids collapsed
to form PAA nanogels, in which HPC acted as a template for the
formation of nanogels.
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Introduction(3/3)
4.Herein, using HPC as a template in the absence of surfactant, we
synthesized HPC/PMAA nanogels which were dual-responsive to pH
and temperature owing to the interpolymer hydrogen bonding between
HPC and PMAA, and the influence of polymerization temperature,
crosslinker concentration, and HPC concentration to effect size and size
distribution of dual-responsive nanogels were systematically studied.
PMAA
(聚甲基丙烯酸)
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Outline
Introduction
Experimental
Results and discussion
Conclusions
6
Experimental
-Materials
• Hydroxypropylcellulose (HPC) powders (average Mw = 1.0 × 105 )
• Methacrylic acid monomers (MAA, 99%)
• N , N′-methylenebisacrylamide (BIS, crosslinker, 99%)
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Experimental
-Materials
• Ammonium persulfate (APS, 99%, initiator)
• N , N , N′, N′-tetramethylethylenediamine (TEMED)
• Sodium hydroxide (NaOH)
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Experimental
-Aqueous synthesis of nanogels
1 wt.% HPC (aq) 20g
dissolving HPC powder in deionized water under
gentle stirring for one week at room temperature
0.3 g MAA
0.1 g crosslinking agent BIS
0.1 g APS
dissolved in 79.4 g DI water under stirring for 60
min to make a homogenous solution.
HPC nanogels
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Experimental
The HPC/MAA solution
0.05 g TEMED
Nanogels were dialyzed for 3 days
purged with nitrogen for 40 min and heated up to
30 °C ,stabilizing for 20 min.
initiate polymerization and crosslinking to
proceed for 60 min
remove the unreacted MAA, BIS, and TEMED
deprotonated to pH = 6.5 ± 0.1 by NaOH
DLS
UV–Vis
spectrophotometer
FTIR
TEM
AFM
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Experimental
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Outline
Introduction
Experimental
Results and discussion
Conclusions
12
Results and discussion
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Results and discussion
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Results and discussion
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Results and discussion
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Results and discussion
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Results and discussion
PMAA
(聚甲基丙烯酸)
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Results and discussion
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Outline
Introduction
Experimental
Results and discussion
Conclusions
20
Conclusions(1/2)
1.Dual-responsive HPC nanogels have been synthesized using HPC as a
template in surfactant-free aqueous media.
2.It was found that the average size of HPC nanogels changed little with
increasing polymerization temperature below 26 °C, whereas it greatly
increased above 26 °C.
3.When the concentration of HPC was increased from 0.1 to 0.9 wt.%,
the diameter of nanogels decreased firstly and then increased.
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Conclusions(2/2)
4.Besides, an increasing crosslinker BIS concentration led to a reduced
size of HPC nanogels, and the nanogels had the narrowest size
distribution when its concentration was 0.1 wt.%. It was demonstrated
that nanogels were both thermo sensitive and pH sensitive due to the
coexistence of HPC and PMAA.
5.This green method to prepare HPC nanogels in aqueous solution
without surfactant can effectively prevent organic solvent from
polymerization system. Dual-responsive HPC nanogels are promised to
be used in the field of drug delivery and other nanobiomaterials.
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Thank you for your attention