Full Paper

Facile Synthesis of Nanocapsules and HollowNanoparticles Consisting of FluorinatedPolymer Shells by Interfacial RAFTMiniemulsion Polymerization

Hao Chen, Yingwu Luo*

Nanocapsulesmade of a cross-linked poly(dodecafluoroheptyl acrylate) shell were successfullysynthesized by interfacial RAFT miniemulsion polymerization. The well-defined hollowfluorinated polymer structures were obtained by the subsequent removal of the liquid corematerials. The core/shell ratio could be easily tuned up to 1:1 by changing the conditions. Inthe cases of high core/shell ratio of 1:2 and 1:1, the nanocapsules were severely deformed,which was improved by increasing the cross-linker amount up to 30wt.-%. It was concludedthat the utility of the interfacial RAFTminiemulsion polymerization overcamethe thermodynamic and kinetic barriersin a conventional miniemulsion polymeri-zation.

Introduction

In the past decades, synthesis of polymer nanocapsules of

active substance or hollow polymer nanoparticles has

received tremendous attentions due to their potential

applications in many emerging fields like drug delivery,[1]

dye encapsulation,[2] catalysis,[3] and biomaterial sensor.[4]

Many kinds of polymers such as polyelectrolytes,[5,6]

polystyrene,[7–9] poly(butyl acrylate),[10] poly(L-lactide),

polycaprolactone/poly(ethylene oxide) block copoly-

mers,[11] and polyethylcyanoacrylate[12] were used as

polymer shell of nanocapsules for entrapping different

materials in core. Due to the strongest C–F single bonds

among organic molecules, low polarity, and good coverage

of polymermain carbon chains, fluorinated polymers show

many unique properties like low refractive index, high

H. Chen, Y. LuoThe State Key Laboratory of Chemical Engineering, Department ofChemical and Biochemical Engineering, Zhejiang University,Hangzhou 310027, ChinaFax: þ86 571 8795 1612; E-mail: yingwu.luo@zju.edu.cn

Macromol. Chem. Phys. 2011, 212, 737–743

� 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlin

oxygen andCO2 permeation, low surface energy,water and

oil repellence, chemical and thermal stability.[13–15] Nano-

capsules or nanoparticles with fluorinated polymer shells

would be of interest in many applications such as use as

oxygen carrier,[16] membranes for fuel cells, etc.[17,18]

However, to our best knowledge, there are no reports on

the synthesis of nanocapsules and hollow nanoparticles

with fluorinated polymer shells.

Manynovel techniqueshavebeen invented tosynthesize

polymernanocapsules orhollowstructures. Representative

techniques include block copolymers self-assembly in

selective solvents,[19–25] miniemulsion polymeriza-

tion,[8,9,26–28] and template methods such as layer-by-layer

assembly of inorganic silica on particles,[29] deposition on

mini-droplets,[30] or surface polymerization on nanoparti-

cles.[31] Among these techniques,miniemulsion polymeriza-

tion, particularly the interfacial reversible addition/

fragmentation chain-transfer (RAFT) miniemulsion poly-

merization, presents a convenient, green, highly efficient,

andscalableversatileapproach.[8,9]Astablefluorinated latex

has been successfully achieved by miniemulsion copoly-

merization of fluorinated (meth)acrylate and styrene/

elibrary.com DOI: 10.1002/macp.201000664 737

738

www.mcp-journal.de

H. Chen, Y. Luo

methacrylate/acrylic acid using sodium dodecylsulfate

(SDS) as surfactant.[32] Compared with the emulsion

polymerization, the monomer transport problem of fluori-

nated monomer can be solved by the direct conversion of

monomer droplets into the particles in miniemulsion

polymerization, where monomer is in the pre-emulsified

minidroplets of about 100nm in diameter before initiating

the polymerization. In a miniemulsion polymerization,

nanoencapsulationof a liquid substance is fulfilled through

phase separationwithin the particles,which is triggered by

the polymerization.[28] Polymer nanocapsules of the liquid

substance are only formed when the polymer shell is more

hydrophilic than the corematerials and the polymer chains

newly created in the aqueous phase can transport to the

particle surface before precipitation.[28] Considering the

superhydrophobic nature of most fluorinated polymer, the

formation of the fluorinated polymer shell is particularly

difficult, according toTorza andMason[33] andSundberg.[34]

On the other hand, the cross-linked polymer shell is also

difficult to achieve since the cross-linked polymer clusters

are difficult to move to the surface of particles.[28]

Beinga typeof controlled/living radical polymerizations,

RAFT polymerization has been extensively investigated in

the past decade.[35,36] Using RAFT polymerization, the

synthesis of well-defined polymers with a low polydisper-

sity index (PDI),[37] block copolymers,[38] and gradient

polymers with controlled compositional profile along the

polymer chains,[39] and polymer brushes grafted on a

surface[40] has been achieved. More recently, an interfa-

cially-confined RAFT miniemulsion polymerization pro-

cess, which was constructed by using an amphiphilic

oligomeric RAFT agent as surfactant, was demonstrated to

be a straightforward route to synthesize the nanocap-

sules.[8,9] In the process, the amphiphilic oligomer RAFT

agent molecules initially anchored at the interface of oil or

particles would grow gradually in a living manner during

the polymerization course, leading to the in situ formation

of polymeric shell.[8,9] The nanocapsules of polystyrene

surrounding hexadecane core have been successfully

synthesized with different amphiphilic oligomeric RAFT

agents.[8,27,41] Here we report the well-defined nanocap-

sules and hollow nanoparticles with the cross-linked

fluorinated polymer shell, which cannot be obtained by

the conventional miniemulsion polymerization, can be

synthesized by the RAFT interfacial miniemulsion poly-

merization.

Scheme 1. Reactions to synthesize the amphi-RAFT agent.

Macromol. Chem. Phys. 2

� 2011 WILEY-VCH Verlag Gmb

Experimental Part

Materials

Dodecafluoroheptyl acrylate [DFHA, (CF3)2CFCFHCF(CF3)CH2OOCC¼CH2], purchased from Xeogia Fluorine-Silicone Chemicals (Harbin,

China), and methacrylic acid [MAA, analytic reagent (AR)] were

purified by distillation under reduced pressure to remove inhibitor

before use. 4-Cyano-4(dodecylsulfanylthiocarbonyl)sulfanylpen-

tanoic acid (CDPA), as the initial RAFT agent, was synthesized and

purified as described in the literature.[42] 2,2’-Azoisobutyronitrile

(AIBN) as an initiator for miniemulsion polymerization was re-

crystallized twice from methanol. Divinylbenzene (mixture of

isomers, 80%) purchased from J&KChemical Ltd. waswashedwith

an aqueous solution of 10wt.-% sodiumhydroxide and then rinsed

withde-ionizedwater to remove inhibitorbeforeuse. 4,4’-Azobis(4-

cyano-pentanoic acid) (V501, initiator for the solution polymeriza-

tion, 99%, from Aldrich), dioxane (>99%, AR), hexane (AR),

tetrahydrofuran (THF, AR), sodium hydroxide (NaOH, AR), hydro-

chlorie acid (>99%), hexadecane (HD, 99%, from Alfa Aesar), hexyl

acetate (HA, Aladdin), sodium nitrite(>96%, AR), and SDS (96%)

were used without further purification.

Synthesis of the Amphiphilic Poly(MAA-co-DFHA)RAFT Agent

The amphiphilic poly(MAA-co-DFHA) RAFT agent (amphi-RAFT)

was synthesizedvia the solutionpolymerizationofMAAandDFHA

mediated by the small RAFT agent CDPA, as seen in Scheme 1. The

small RAFT agent CDPA (2 g, 4.96mmol), the initiator V501 (0.21 g,

0.71mmol), and fluorine-monomer DFHA (17.2 g, 44.56mmol),

MAA (7.88 g, 91.6mmol) were mixed and dissolved in dioxane

(40.7 g, solvent with small transfer coefficient). The solution was

introduced into a 150mL four-necked round flask. After N2

bubbling for 30min, the polymerization proceeded with magne-

tically stirring for 8 h at 80 8C. The product (amphi-RAFT) of yellow

solid powderwas then collected by precipitating the solution three

timeswith icy hexane and then dried in a vacuumoven at 30 8C for

3 h. The overall monomer conversion from gravimetric analysis

was about 35%.

1H NMR Analysis

The structure of the amphi-RAFT agent was determined by Bruker

Avance DMX 500MHz spectrometer with DMSO-d6 as NMR

solvent. The 1H NMR spectrum of the amphi-RAFT is shown in

Figure 1 including signal assignment. From the spectrum, it was

estimated using Equation (1) and (2) that each amphi-RAFT agent

moleculehad7.0MAAunits and2.1DFHAunits,whichagreedwell

011, 212, 737–743

H & Co. KGaA, Weinheim www.MaterialsViews.com

Figure 1. 1H NMR spectrum of the amphi-RAFT agent recorded inDMSO-d6.

Facile Synthesis of Nanocapsules and Hollow Nanoparticles . . .

www.mcp-journal.de

with the conversion data,

Tab

Ru

Exp

Exp

Exp

Exp

Exp

a)Weig

www.M

NMAA ¼ I�COOH�0:5I�CH2�COOH

0:5I�CH2�COOH(1)

NDFHA ¼ I�CHF�0:5I�CH2�COOH

(2)

whereNMAA is the number ofMAA unit in each amphi-RAFT agent

molecule; NDFHA is the number of DFHA unit in each amphi-RAFT

agent molecule; I–COOH is the integral area of the peak at d¼ 12.4,

I�CH2�COOH is the integral area of the peak at d¼2.3, and I–CHF– is

the integral area of the peak at d¼6.4. The reactivity ratios ofMAA

and DFHA were not available in the literature. Due to the

structural similarity, the reactivity ratios of MAA and butyl

acrylate (rMAA/BA¼1.31, rBA/MAA¼ 0.35[43]) was used to calculate

the theoretical copolymer composition by Mayo-Lewis equa-

tion[44] and the result was also in good agreement with 1H NMR

data.

le 1. Recipe for the synthesis of cross-linked fluorinated polymer

n AIBN Total monomers Core/shell

weight ratioa)DVBb)

mmol g %

1 3.65 16.0 1:4 10

2 3.65 13.3 1:2 10

3 5.48 13.3 1:2 30

4 3.65 10.0 1:1 10

5 5.48 10.0 1:1 30

ht of HA and HD (core materials) to total monomers of DFHA

aterialsViews.com

Macromol. Chem. Phys. 2

� 2011 WILEY-VCH Verlag Gmb

Gel Permeation Chromatography (GPC)

AWaters1525/2414/717 (1525binaryHPLCpump,2414refractive-

index detector, 717 autosampler) GPC systemwas used to analyze

molecular weight and its distribution of the amphi-RAFT agent.

ThreeWaters Styragel columns HR 4, 3, 1 were used. THFwas used

as eluent with a flow rate of 1mL �min�1. Mn of the amphi-RAFT

agent relative to polystyrene was 1 728 g �mol�1, and the PDI was

1.07. Interestingly, themolecularweight fromGPC agreedwith the

the value (1 816g �mol�1) calculated from the1H NMR spectrum

using Equation (3):

nanoc

Core

and DV

011, 21

H & Co

Mn ¼ MRAFT þNMAAMMAA þNDFHAMDFHA (3)

where MRAFT, MAA, and MDFHA are the molar mass of CDPA, MAA,

and DFHA respectively.

Preparation of Shell Cross-Linked Fluorinated

Nanocapsules via Interfacial RAFT Miniemulsion

Polymerization

0.5 g (0.1786mmol) amphi-RAFT (used in all experiments listed in

Table 1) was dissolved in 25g de-ionized water with 0.07 g

(1.75mmol) NaOH. After filtration, the amphi-RAFT aqueous

solution was re-filled with de-ionized water up to 74.9 g. 0.1 g

(1.45mmol). NaNO2 as an aqueous free radical scavenger[45] was

then added to the amphi-RAFT solution. Then pH value of the

aqueous amphi-RAFT solution was adjusted to 6.46. The oil phase

the total weight of which was fixed at 20 g contained the pre-set

corresponding amounts of fluorine-monomer DFHA and cross-

linking agentdivinylbenzene (DVB),HD,HA, andAIBN (see Table 1)

were stirred magnetically for 0.5 h at 28 8C. The aqueous solution

was then mixed with the oil phase. The mixture was stirred

magnetically for0.5h forpre-emulsification. The resultedemulsion

was then subjected to sonication using the ultrasonic processor

(JOY-II) at a power output of 600W for 15min at 25 8C to obtain the

miniemulsion. 5mL de-ionized water which contained 0.2 g SDS

was post-added to the obtained miniemulsion under stirring. The

resultedminiemulsionwas then transferred to a 250mL four-neck

round bottomglass flaskwith amechanical stirrer, a rubber plug, a

reflux cooler, and a N2 bubbler. The miniemulsion polymerization

apsules.

materials HA/HD Conversionb) HA/HD

g weight ratio %

4 1 88 1

6.7 1 84 1

6.7 1:2 92 1:2

10 1:2 85 1:2

10 1:2 84 1:2

B (precursors for shell); b)Based on total monomer weight.

2, 737–743

. KGaA, Weinheim739

740

www.mcp-journal.de

H. Chen, Y. Luo

was initiated at 70 8C after having highly pure N2 bubbled for

15min. The polymerization lasted for 6h under N2 protection. The

final monomer weight conversion in this work was all over 80%.

Fabrication of Hollow Cross-Linked Fluorinated

Polymer Particles

The latex product of the miniemulsion polymerization was de-

emulsified by adding several drops of hydrochloric acid. The

polymer solid was collected by suction filtration with a large

numberofdeionizedwaterandthendried to removeresiduewater.

The collected polymer solid was re-dispersed in THF by magne-

tically stirring for 24h to replace the core material mixture of HA

andHD. Then thewhite polymer solidpowderwasprecipitatedout

by adding hexane to THF and was dried at 40 8C for 2 h under

vacuum.

pH Measurement

ThepHof theaqueousamphi-RAFTsolutionwasmonitoredbyapH

meter (LEICI PHS-2C) with an electrode E-201-C.

DSC Analysis

The glass transition temperature (Tg) of the copolymer was

measured with a Q200 differential scanning calorimeter (TA

instruments). The samplewas cooled to –60 8C at 50 8C �min�1 and

maintained for 2min, then scanned at a heating rate of

20 8C �min�1 from –60 to þ140 8C.

Fourier-Transform Infrared (FT-IR) Spectroscopy

IR spectra were measured on a Nicolet 5700 infrared spectrometer

with using DTGS KBr detector. The dried hollow cross-linked

fluorinated polymer particles cast onto KBr disk. The sample

concentration in the disks was 1wt.-%.

Gel Fraction Measurement

The fluorinated copolymer were collected from the latex by being

dried at 160 8C under vacuum for 4h to remove core materials HA

and HD. 0.6 g dried copolymer was packaged by filter paper, and

was extracted for 48h with THF as solvent in a Soxhlet extractor.

The package was then vaporized at room temperature and then

dried under vacuum at 40 8C until constant weight (W). The gel

fraction (Gc) was calculated from Equation (4):

Gc ¼0:6�W

0:6(4)

Transmission Electron Microscopy (TEM)

TEM was performed on JEM-1230 from JEOL at the operating

voltage of 80 kV. The samples were made by dipping 200-mesh

carbon-coated coppergrids into thediluted latexproducts and then

dried at room temperature for a while.

Macromol. Chem. Phys. 2

� 2011 WILEY-VCH Verlag Gmb

Scanning Electron Microscopy (SEM)

The hollow fluorinated polymer particles were observed by SEM

(Hitachi S4800 and ULTRA 55, 5.0 kV).

Results and Discussion

Synthesis of Shell Cross-Linked Fluorinated PolymerNanocapsules

In the case of polystyrene nanocapsules, it has been found

that the homogeneous nucleation could lead to the

formation of the solid particles.[41] When the amphiphilic

RAFT agent was designed to be a random copolymer of

styrene and methyl methacrylate, the homogeneous

nucleation could be suppressed by lowering pH values.[41]

The same strategy was adopted here. So, the amphi-RAFT

agent was designed to be the random copolymer of MAA

andDFHA, and thepHvaluewasadjusted to6.46. To further

suppress the homogeneous nucleation, the oil-soluble

initiator AIBN was used, and NaNO2 was added to be an

aqueous radical scavenger.[45] Once the miniemulsion was

formed, a small fraction of SDS was added to prevent the

possible coagulation of the minidroplets. In our first

experiment (Exp 1, see Table 1), the core/shell weight ratio

was set to 1:4. The core materials were the mixture of half-

to-half HD and HA, of which HA was co-solvent of

monomers and HD. DVB is cross-linker, which would

covalently hold the polymer shell to be an integrity. The gel

fraction of the product polymer was measured to be 99%,

suggesting the fluorinated polymer shell was highly cross-

linked. The typical TEM image of the particle product from

the miniemulsion polymerization is presented in

Figure 2(a). From Figure 2(a), most particles have a core/

shell structure and statistic from TEM image shows that

more than 95% of total existing particles are nanocapsules

except those small solid particles whose diameters are

below 60nm. The particle sizes are from 30 to 200nm in

diameter with the statistical number-average diameter

Dn

� �114nm,number-average shell thickness dn

� �15.8 nm,

and coefficient of variation (CV) 26.9%. The shell thickness

agrees well with the theoretical shell thickness

[dn;theo ¼ 15.3 nm], calculated using Equation (5):

011, 21

H & Co

dn;theo ¼Dn

2� 1�

ffiffiffiffiffiffiffiffiffiffiffiffiffirs�rdrs�rc

3

r� �(5)

where rs is the density of the polymer shell of the

nanocapsules, rd is the density of miniemulsion droplets

before polymerization, and rc is the density of core

materials within a few monomers according to corre-

sponding conversion. The core/shell weight ratio of

the resulted nanocapsules was statistically estimated to

be 1:2.5 from TEM data, which is close to the theoretical

2, 737–743

. KGaA, Weinheim www.MaterialsViews.com

Figure 2. Typical TEM images of particles from (a) the interfacial RAFT miniemulsionpolymerization; (b) the conventional miniemulsion polymerization.

Facile Synthesis of Nanocapsules and Hollow Nanoparticles . . .

www.mcp-journal.de

value 1:2.4 at 88% monomer conversion. From the TEM

image, some particles are deformed. From DSC, the glass

transition temperature (Tg) of the polymer shell was

estimated to be about 13 8C. Such a deformation of

particles may be understandable considering HA might

be partly vaporized during TEM measurement.

As a comparison, the conventional miniemulsion poly-

merization with 0.6 g SDS as surfactant replacing the

amphi-RAFT as surfactant was carried out. 1wt.-% MAA

based on the total monomer was used, whichwas found to

facilitate the formation of core/shell structures.[26] Actu-

ally, theMAA amount incorporated in the polymerwas the

same as the preciously interfacial RAFT miniemulsion

polymerization. The resultedparticles are irregularwithout

clear core/shell structures as evidenced in Figure 2(b).

This is expected from both thermodynamics and

kinetics aspects. In thermodynamics, poly(DFHA) is more

Figure 3. FT-IR spectrum of hollow fluorinated polymer particles(Exp 1).

www.MaterialsViews.com

Macromol. Chem. Phys. 2011, 212, 737–743

� 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinh

hydrophobic than the mixture of HD/HA.

According to Torza and Mason[33] and

Sundberg,[34] thenanocapsuleswithpoly-

mer shell should not be thermodynami-

cally preferred. In kinetics, it has been

shown that the cross-linked polymer

shells are often difficult to form due to

the failure of movement of cross-linked

polymer chains in a conventional (mini)-

emulsion polymerization.[28] The sharp

contrast in the particle morphology as

evidenced in Figure 2(a) and (b) clearly

suggests that the interfacial RAFT mini-

emulsion polymerization overcomes not

only the kinetic but also thermodynamic

barriers to form well-defined core-shell

structures, which are often confronted in

the conventional miniemulsion polymerization. Figure 3

shows the FT-IR spectrum of the hollow cross-linked

fluorinated polymer particles of Exp 1. The characteristic

signals of poly(DFHA) are seen from the C¼O stretching

peak at 1 760 cm�1, the peaks of 1 250 and 1 171 cm�1

associated with the motions of the –CF2– chain, and the

peak at 692 cm�1 from the combination of rocks and

wagging vibration of –CF2CF3 groups. The absorption peaks

withmoderate intensity at 1454and900 cm�1 are fromthe

aromatic ring of DVB. A broad absorption peak from –OH is

seen at 3 490 cm�1, indicating that –COOH groups derived

from the amphi-RAFT agent were still anchored on the

surface of the hollow fluorinated polymer particles.

The Influence of Core/Shell Ratios on the ParticleMorphology

The core/shell ratio of the nanocapsules was adjusted by

changing the weight ratio of monomers to core materials

from 1:4 (Exp 1), 1:2 (Exp 2) to 1:1 (Exp 4), as referred to

Table 1. In the case of Exp 1 and Exp 2,moreHA is needed to

formahomogeneous oil solution.With the core/shell ratios

increased, the core/shell structures look more deformed

under TEM as evident in Figure 4(a) and (b) [note: the

particle morphology of Exp 1 is shown in Figure 2(a)]. The

theoretical simulations have shown that the mechanical

properties could dramatically decrease when decrease in

thickness for a nanolayer of polymer.[46] To increase the

mechanical strength of the polymer shell, the cross-linker

amountwas increasedupto30wt.-% (Exp3andExp5, see in

Table 1). As seen in Figure 4(c) and (d), the core/shell

particles become much less deformed, as expected. In such

cases, for the core/shell ratio 1:2 (Exp 3), Dn ¼ 94nm,

CV¼ 31.6%, and dn ¼ 8.9 nm, which is a little thinner than

the theoretical value 9.7 nm. The average core/shell weight

ratio of the resulted nanocapsules is 1:1.3, compared to

the theoretical 1:1.5 (92% total monomers conversion). In

eim741

Figure 4. TEM images of fluorinated polymer nanocapsules with different core/shellratios prepared via interfacial RAFT miniemulsion polymerization. (a) 1:2, 10wt.-% DVB;(b) 1:1, 10wt.-% DVB; (c) 1:2, 30wt.-%DVB; (d) 1:1, 30wt.-% DVB.

Figure 5. TEM and SEM images of hollow fluorinated polymer nanostructures. (a) TEM.(b) SEM.

742

www.mcp-journal.de

H. Chen, Y. Luo

the case of the core/shell ratio 1:1 (Exp 5), Dn ¼ 99nm,

CV¼ 24.2%, and dn ¼ 9.1 nm, thicker than theoretical value

that is 7.7 nm (84% monomer conversion). Form TEM

images, it is found that all the particles are core/shell

structures, even those small particles whose diameters are

below 40nm in Figure 4(c) and (d).

Macromol. Chem. Phys. 2011, 212, 737–743

� 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinh

Hollow Fluorinated PolymerStructures

The hollow fluorinated polymer struc-

tures can be made simply by removing

the liquid core materials. For an example,

the dried nanocapsules of Exp 5 were re-

dispersed in THF. Thus, the corematerials

were replaced by THF. The later THF core

could be easily vaporized at room tem-

perature under reduced pressure. No HD

melting peak was found in DSC measure-

ment of the hollow polymer particles,

indicating that the core materials were

completely removed. From the TEM pic-

tureshowninFigure5(a), thewell-defined

core/shell structures are clearly seen. The

hollow particle shows a bit coarse shell

and somewhat inhomogeneous sphere

shape, due to its shell highly crosslinked.

It is noted that THF is a good solvent for

poly(DFHA), so the polymer shells were

actually cross-linked into integrity so that

the core/shell structures were able to

resist the dissolution of THF. As a matter

of fact,most of thehollownanostructures

remained spherical though a small frac-

tion of collapsed particles were found as

shown in the SEM image of Figure 5(b).

There several hollow particles are

observed having a dimple, this may be

led by the thin shell of the hollow

particles, because a part of the shell

collapsed and left a dimple when core/

shell ratio of thenanocapsules is up to 1:1.

Conclusion

The nanocapsules with cross-linked poly-

(DFHA) shell were synthesized by the

interfacial RAFT miniemulsion polymer-

ization using the amphi-RAFT agent. The

utility of the interfacial RAFT miniemul-

sion polymerization overcame the ther-

modynamic and kinetic barriers in a

conventional miniemulsion polymeriza-

tion. The well-defined hollow fluorinated

polymer structures were obtained by the subsequent

removal of the liquid core materials. The core/shell ratio

was be easily tuned up to 1:1. In the case of high core/shell

ratio of 1:2 and 1:1, the nanocapsules were severely

deformed, which was improved by the increase of DVB

amounts up to 30wt.-%. The resulted hollow nanoparticles

eim www.MaterialsViews.com

Facile Synthesis of Nanocapsules and Hollow Nanoparticles . . .

www.mcp-journal.de

withfluorinatedpolymershellwouldbeof interest inmany

fields such as use as oxygen carriers, fuel cells, and

membranes.

Acknowledgements: This work was financially supported by theNational Science Foundation of China (NSFC) (#20836007) as wellas Program for Changjiang Scholars and Innovative ResearchTeams in University.

Received: October 22, 2010; Revised: December 8, 2010; Publishedonline: January 28, 2011; DOI: 10.1002/macp.201000664

Keywords: fluoropolymers; hollow particles; miniemulsion poly-merization; nanoparticles; reversible addition fragmentationchain transfer (RAFT)

[1] J. Hureauxa, F. Lagarce, F. Gagnadoux, A. Clavreulb, J. P.Benoit, T. Urban, Int. J. Pharm. 2009, 379, 266.

[2] M. Epple, K. Ganesan, R. Heumann, J. Klesing, A. Kovtun,S. Neumann, V. Sokolova, J. Mater. Chem. 2010, 20, 18.

[3] U. Reibetanz, D. Halozan, M. Brumen, E. Donath, Biomacro-molecules 2007, 8, 1927.

[4] H. Hattori, Adv. Mater. 2001, 13, 51.[5] D. Silvano, S. Krol, A. Diasper, O. Cavalleri, A. Gliozzi, Microsc.

Res. Techol. 2002, 536.[6] G. B. Sukhorukov, A. A. Antipov, A. Voigt, E. Donath,

H. Hohwald, Macromol. Rapid Commun. 2001, 22, 44.[7] A. J. P. van Zyl, R. F. P. Bosch, J. B. McLeary, R. D. Sanderson,

B. Klumperman, Polymer 2005, 46, 3607.[8] Y. W. Luo, H. Y. Gu, Macromol. Rapid Commun. 2006, 27, 21.[9] Y. W. Luo, H. Y. Gu, Polymer 2007, 48, 3262.[10] A. J. P. van Zyl, D. de Wet-Roos, R. D. Sanderson,

B. Klumperman, Eur. Polym. J. 2004, 40, 2717.[11] Z. Lu, J. Z. Bei, S. G. Wang, J. Controlled Release 1999, 61, 107.[12] G. Puglisi, M. Fresta, G. Giammona, C. A. Ventura, Int. J.

Pharm. 1995, 125, 283.[13] K. Landerfester, B. Ameduri, B. Boutevin, Actual. Chim. 2000,

2, 23.[14] L. van Ravenstein, W. Ming, R. D. van de Grampel, R. van der

Linde, G. de With, T. Loontjens, P. C. Thune, J. W. Niemants-verdriet, Macromolecules 2004, 37, 408.

[15] I. J. Park, S. B. Lee, C. K. Choi, Polymer 1997, 38, 2523.

www.MaterialsViews.com

Macromol. Chem. Phys. 2

� 2011 WILEY-VCH Verlag Gmb

[16] M. Skiba, M. Skiba-Lahiani, P. J. Arnaud, Intrusion Phenom.Macrocyclic Chem. 2002, 44, 151.

[17] H. Ghassemi, J. E. McGrath, T. A. Zawodzinski, Polymer 2006,47, 4132.

[18] P. Costamagna, S. Srinivasan, J. Power Sources 2001, 102, 242.[19] Y. W. Zhang, M. Jiang, J. X. Zhao, Z. X. Wang, H. J. Dou, D. Y.

Chen, Langmuir 2005, 21, 1531.[20] H. J. Dou, M. Jiang, H. S. Peng, D. Y. Chen, Y. Hong, Angew.

Chem. 2003, 115, 1554.[21] X. K. Liu, M. Jiang, Angew. Chem. 2006, 118, 3930.[22] M. Wang, M. Jiang, F. L. Ning, D. Y. Chen, S. Y. Liu, H. W. Duan,

Macromolecules 2002, 35, 5980.[23] L. F. Zhang, K. Yu, A. Eisenberg, Science 1996, 272, 1777.[24] Y. S. Yu, A. Eisenberg, J. Am. Chem. Soc. 1997, 119, 8383.[25] A. V. Kabanov, T. K. Bronich, V. A. Kabanov, K. Yu,

A. Eisenberg, J. Am. Chem. Soc. 1998, 120, 9941.[26] Y. W. Luo, X. D. Zhou, J. Polym. Sci. Part A: Polym. Chem. 2004,

42, 2145.[27] F. J. Lu, Y. W. Luo, B. G. Li,Macromol. Rapid Commun. 2007, 28,

868.[28] L. J. Gonzalez-Ortiz, J. M. Asua,Macromolecules 1995, 28, 3135.[29] H. Mohwald, R. A. Caruso, F. Caruso, Science 1998, 282, 1111.[30] U. Paiphansiri, P. Tangboriboonrat, K. Landfester, Macromol.

Biosci. 2006, 6, 33.[31] T. von Werne, T. E. Patter, J. Am. Chem. Soc. 2001, 123, 7497.[32] K. Landfester, R. Rothe, M. Antonietti, Macromolecules 2002,

35, 1658.[33] S. Torza, S. G. Mason, J. Colloid Interface Sci. 1970, 33, 67.[34] D. C. Sundberg, A. Casassa, J. Pantazopoulos, M. Muscato,

J. Appl. Polym. Sci. 1990, 41, 1425.[35] J. Chiefari, Y. K. Chong, F. Ercole, J. Krstina, J. Jeffery, T. P. T. Le,

R. T. A. Mayadunne, G. F. Meijs, C. L. Moad, G. Moad,E. Rizzardo, S. H. Thang, Macromolecules 1998, 31, 5559.

[36] G.Moad, J. Chiefari, Y. K. Chong, J. Krstina, R. T. A.Mayadunne,A. Postma, E. Rizzado, S. H. Thang, Polym. Int. 2000, 49, 993.

[37] C. L. McCormick, A. B. Lowe, Acc. Chem. Res. 2004, 37, 312.[38] Y. K. Chong, T. P. T. Le, G. Moad, E. Rizzardo, S. H. Thang,

Macromolecules 1999, 32, 2071.[39] Z. Q. Hu, Z. C. Zhang, Macromolecules 2006, 39, 1384.[40] M. Baum, W. J. Brittain, Macromolecules 2002, 35, 610.[41] F. J. Lu, Y.W. Luo, B. G. Li, Indian Eng. Chem. Res. 2010, 49, 2206.[42] G. Moad, Y. K. Chong, A. Postma, E. Rizzardo, S. H. Thang,

Polymer 2005, 46, 8458.[43] T. R. Paxton, J. Polym. Sci. Part B: Polym. Phys. 1963, 1, 73.[44] F. R. Mayo, F. M. Lewis, J. Am. Chem. Soc. 1944, 66, 1594.[45] Y.W. Luo, J. Schork, J. Polym. Sci. Part A: Polym. Chem. 2002, 40,

3200.[46] J. J. de Pablo, P. F. Nealey, ‘‘Dimension-dependent Properties

of Macromolecules in Nanoscopic Structures’’, in:, The EighthAnnual Symposium on Frontiers of Engineering, NationalAcademies Press, Washington, D. C 2003, p. 11.

011, 212, 737–743

H & Co. KGaA, Weinheim743