Jing Li(李静， 21029019), Xufeng Ni(倪旭峰 )

IntroductiIntroductionon

Polymerization FeaturesPolymerization Features Mechanism of PolymerizationMechanism of Polymerization

Characterization and properties of Characterization and properties of PDEVPPDEVP

Reference1 J. Ellis, A. D. Wilson, Dent. Mater. 1992, 8, 79–84.

2 H. Steininger, M. Schuster, K. D. Kreuer, B. Bingoel, W. H. Meyer, Phys. Chem. Chem. Phys. 2007, 9, 1764–1773.

3 T. Wagner, A. Manhart, N. Deniz, M. Wagner, W. H. Meyer, Macromol. Chem. Phys. 2009, 210, 1903–1914.

4 B. Bingol, W. H. Meyer, M. Wagner, G. Wegner, Macromol. Rapid Commun. 2006, 27, 1719–1724.

5 G. W. Rabe, H. Komber, L. Haeussler, K. Kreger, G. Lattermann, Macromolecules. 2010, 43, 1178–1181.

6 U. B. Seemann, J. E. Dengler, B. Rieger, Angew. Chem. Int. Ed. Engl. 2010, 49, 3489–3491.

7 S. Salzinger, U. B. Seemann, A. Plikhta, B. Rieger, Macromolecules. 2011, 44, 5920–5927.

8 N. Zhang, S. Salzinger, F. Deubel, R. Jordan, B. Rieger, J. Am. Chem. Soc. 2012, 134, 7333–7336.

9 Jing Li, Xufeng Ni*, Jun Ling, Zhiquan Shen, Journal of Polymer Science, Part A: Polymer Chemistry 2013, DOI:

10.1002/pola.26626.

　　 Polymeric materials containing covalently bonded heteroatoms, particularly phosphorus containing polymers are interesting for a wide field of science and

applications1,2. To date, many attempts to polymerize vinylphosphonate monomers have been reported including radical polymerization3, anionic polymerization4 and rare

earth catalytic polymerization5-8. Here, we report the controlled polymerization of DEVP initiatedby lanthanide borohydrides, Ln(BH4)3(THF)3 (Ln = Y, La, Nd, Sm, Gd,

Dy, Lu). The polymerization features, kinetics and mechanism of the polymerization are discussed; the structures and the properties of obtained poly(diethyl

vinylphophonate)s (PDEVPs) are characterized9.

ConclusionsConclusions

Syntheses and Properties of Poly(diethyl vinylphosphonate) Initiated by Lanthanide Tris(borohydride) Complexes: Polymerization controllability and Mechanism

Department of Polymer Science and Engineering, MOE Key Laboratory of Macromolecular Synthesis and Functionalization,Zhejiang University, Hangzhou, 310027, China

Acknowledgments

The authors gratefully acknowledge the financial supports of the National Natural Science Foundation of China (21174121) and the Special Funds for Major Basic Research Projects (G2011CB606001).

0 50 100 150 200 250 30055

60

65

70

75

80

85

90

95

100

Gd La Sm

conv

ersi

on(%

)

time(min)Figure 1 Determination of the catalytic activity of Gd (BH4)3(THF)3 ,

La(BH4)3(THF)3, Sm(BH4)3(THF)3 for the polymerization of DEVP

Reaction conditions: 40°C, 1 h, in bulk, [M]/[Ln]=300.

0 10 20 30 40 50 60

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

time(min)

ln(M

0/M)

Figure 2 ln(M0/M) versus time for the polymerization of DEVP

Conditions: [M]/[Gd]=300:1, 40°C, in bulk.

55 60 65 70 75 80 85 90 95

20000

25000

30000

35000

Conversion(%)

Mn

Mn MWD

10

8

6

4

2

0

MW

D

500 1000 15000

20

40

60

80

100

1501

1337

1173

1151

1009

987

845

823

681

659

517

495

Rel

ativ

e A

bu

nd

ance

(%)

m/z

Figure 8 1H NMR spectra by Bruker Avance III 500 of oligomeric PDEVP terminated by ethyl iodide (Gd(BH4)3(THF)3, 10 eq DEVP)

Figure 7 1H NMR recorded by Bruker Avance III 500 of oligomeric PDEVP terminated by benzyl chloride (Gd(BH4)3(THF)3, 10 eq DEVP)

Figure 6 ESI-MS analysis of oligomeric PDEVP (Gd(BH4)3(THF)3, 5 eq DEVP)

Figure 3 Relationship of conversion and Mn, MWD in polymerization of DEVP

Conditions: [M]/[Gd]=300:1, 40°C, in bulk

Scheme 1 Polymerization mechanism of DEVP catalyzed by Ln(BH4)3(THF)3

8 10 12 14 16 18 20

elution time(min)

30 35 40 45 50 55 60 65 70 75

0

20

40

60

80

100

Tra

nsm

itta

nce(

%)

Temperature(oC)

Figure 5 Change of transmittance at λ=550 nm for PDEVP at 1 mg/mL catalyzed by Gd(BH4)3(THF)3

Figure 4 GPC trace of PDEVP catalyzed by Gd(BH4)3(THF)3

Reaction conditions: 40°C, 1 h, in bulk, [M]/[Ln]=300.

1.Lathanide tris(borohydride) complexes, Ln(BH4)3(THF)3 (Ln = Y, La, Nd, Sm, Gd, Dy, Lu), have been applied to initiate the polymerization of DEVP.

2.The initiators exhibit high activities producing PDEVP in quantitative yields within 1 h polymerization. The kinetics of the polymerization indicates that the polymerization undergoes a controlled manner.

3.The thermal analysis of obtained PDEVPs shows a two-step decomposition and a Tg at about 262oC. The thermosensitive behavior is observed by UV transmittance of aqueous solution of PDEVPs, which shows a LCST about 50oC.

4.A coordination anion polymerization mechanism is proved by end group analysis using ESI-MS and NMR spectra.

Ln(BH4)3(THF)3 + PO

OEt

OEt LnPO

OEt

OEt

H3BH

LnPO

OEt

OEt

CH

H2CHBH3

Ln PO

OEt

OEt

CH

HBH3

P

O

EtO

OEt

DEVP

DEVP

(n-2)DEVP

PO

OEt

OEt

CH

HBH3

Ln

P

O

EtO

OEt PO

OEt

OEtn-2

-BH3

(IV) RX = HOH+RX

(V) RX = PhCH2Cl, EtI

PO

OEt

OEt

CHP

O(EtO)2

PO

OEt

OEtn-2

CH2

H

PO

OEt

OEt

CHP

O

(EtO)2

PO

OEt

OEtn-2

CH2

R

(I)

(II)

(III)

LnPO

OEt

OEt

C

HBH3

P

O

EtO

OEt

H

H

8.0 7.2 6.4 5.6 4.8 4.0 3.2 2.4 1.6 0.8 0.0

7.5 7.4 7.3 7.2 7.1 1.12 1.04 0.96

CH

CH2 CH2

PO OCH2CH3

OCH2CH3

CH

P

CH3

O OCH2CH3

OCH2CH3

n-1ab

c

de

f

gh

i

4.0 3.2 2.4 1.6 0.8 0.0

1.08 1.04 1.00 0.961.26 1.24 1.22

CH

CH2 CH2

PO OCH2CH3

OCH2CH3

CH

P

CH3

O OCH2CH3

OCH2CH3

n-1ab

c

de

f

g

CH3

h

In order to figure out the polymerization mechanism, oligomers have been produced by using 5 to 1 ratio of DEVP to catalyst and are subsequently analyzed by ESI-MS. Besides, benzyl chloride and ethyl iodide are chosen to terminate polymerization of DEVP using 10 to 1 ratio of DEVP to catalyst.

For all peaks in Figure 6, the molecular mass of the corresponding oligomers is found to be Mn(DEVP).n+2 g mol-1. The remaining 2 g mol-1 corresponds to two hydrogen atoms, one of which initiates chain growth and another of which comes from the termination reaction during moisture work-up. More evidences can be seen from analysis of end groups of oligomeric PDEVP terminated by benzyl chloride and ethyl iodide illustrated in Figures 7 and 8.

From all results above, a coordination anion polymerization mechanism for the polymerization of DEVP catalyzed by Ln(BH4)3(THF)3 is shown in scheme 1.

The catalytic activity of Gd(BH4)3(THF)3 , La(BH4)3(THF)3

and Sm(BH4)3(THF)3 are measured as illustrated in Figure 1,

and the results clearly reveal that the catalytic efficiency is strongly affected by the radius (and therefore also the Lewis acidity) of the lanthanide metal center.

The kinetics of the polymerization is investigated, and a linear growth of ln(M0/M) with time can be observed which

proves that the conversion increases with molecular weight and the catalyst has a highly catalytic activity from the start of polymerization (Figure 2). A linear relationship between the molecular weight and conversion proves that the polymerization can be controlled to a certain extent, but the plot without going through the origin indicates that it’s not a ‘real living polymerization’.

All the polymers obtained have a similar unimodal distribution as shown in Figure 4. The amphiphilicity of PDEVP is further underlined by the existence of a lower critical solution temperature (LCST) of aqueous PDEVP solutions. PDEVP has a thermosensitive behavior which is transparent in water below 50oC but turns to nontransparent over 50oC ( Figure 5) .