10 15 20 25 30 35 40 45 500

50000100000150000200000250000300000350000400000450000500000

40

50

60

70

80

90

100

1.20 1.19 1.171.19

1.18

DP of template copolymer (PVBT)

Dau

ghte

r pol

ymer

Mn

(kg/

mol

)

Mic

ella

r Int

ensi

ty d

iam

eter

, Iav

(nm

)

15 17 19 21 23 25 27

6 13 22 34 41 48

Retention Time (mins)

5000 10000 15000 20000 25000 30000 35000 40000 4500030

40

50

60

70

80

90

100

110Core Size Exp.Overall Size Exp.

Mn of template polymer (kg/mol)

Mea

n in

tens

ity d

iam

eter

, Iav

(nm

)

13 16 19 22 25 28 31

61-11 129-22 281-44

Retention Time (mins)

TP Mn

(g/mol)Daughter Polymer (PVBA)

Mn (g/mol) Mw (g/mol) Đ

PSt129-b-PVBT615200 - - -

PSt129-b-PVBT1316900 348850 418334 1.20

PSt129-b-PVBT2219100 318650 439291 1.19

PSt129-b-PVBT3422000 323100 377674 1.17

PSt129-b-PVBT4123700 333714 397563 1.19

PSt129-b-PVBT4825400 342249 402106 1.18

Lim Dong QuanSupervisor: Prof. Per B Zetterlund

Template Radical Polymerisation with VBA

Micelle Core Size effect

• Figures below shows Size Exclusion Chromatography (SEC) trace of polymer mixture (PSt-b-PVBT and PVBA)

• GPC using DMAc as eluent• Higher MW polymer will have a shorter retention time

[1] Ronan McHale, J.P.P., Per. B. Zetterlund, Rachel K.O'Reilly, Biomimetic Radical Polymerization via Cooperative Assembly of Segregating Templates. Nature Chemistry, 2012: p. 491-497.[2] Tan, Y.Y., The Synthesis of Polymers by Template Polymerization. Progress in Polymer Science, 1994. 19: p. 561-588.[3] Masel, R.I., Principles of Adsorption and Reaction on Solid Surfaces. 1996, Urbana: John Wiley & Sons, Inc.

Fine tuning template radical polymerisation in micellar nanoreactors

Templating Effect• Radical polymerisation of monomer lined-up against a template polymer (TP)• Interactions between polymer units and monomer e.g. hydrogen bonding• Assumes Langmuir adsorption model[2][3]• Termination rate constant, kT decreases• Overall rate of polymerisation, Rp increases

Tp°C

Initiator

Aims and Objective To form different lengths of template diblock copolymers (PSt-b-

PVBT) as micelle building blocks (unimers) by: (1) manipulating the PVBT block DP whilst keeping PSt block constant (2) increasing the overall size of template polymer

Characterise the micelle size formed by dissolving TP in CHCL3

Perform template radical polymerisation of VBA monomers in CHCl3 in the presence of template polymers with AIBN as initiator

Segregated Micelles• Micelle act as nanoreactors• Approximately one radical per micelle• Termination rate constant, kT decreases• One daughter chain per micelle

Overall Micelle Size effect

Introduction

Micellisation10 mg of diblock

copolymer

Dissolved in 1 ml of CHCl3

Template Polymer Synthesis

129

61322344148

Micelle Core Size Overall Micelle Size

61 11

22

44

129

281

Degree of polymerisation,

DP

[PSt] (mol/L)

[VBT] (mol/L)

HoursX

(%)Ð

Mn

(g/mol)

Mw

(g/mol)

Core Size

PSt129-b-PVBT6 0.012 0.657 20 15 1.25 15209 18999PSt129-b-PVBT13 0.012 0.688 64 27 1.30 16905 22020PSt129-b-PVBT22 0.012 0.688 121 45 1.30 19085 24872PSt129-b-PVBT34 0.005 0.602 20 33 1.26 21993 27627PSt129-b-PVBT41 0.005 0.590 20 39 1.27 23688 30099PSt129-b-PVBT48 0.012 1.376 20 29 1.32 25384 33627

Overall Size

PSt61-b-PVBT11 0.002 0.643 14 15 1.29 8997 11568PSt129-b-PVBT22 0.012 0.688 121 45 1.30 19085 24872PSt281-b-PVBT44 0.005 0.787 - 38 1.38 40622 55957

• VBT added to PSt in DMF @125°C to synthesize template polymer (TP)

• NMP (TEMPO-group) polymerisation since inactive at 60°C during TRP with VBA

• Mass ratio of PVBT to PSt in overall micelle size exp. kept constnat at 30%

• Medium dispersity for all at ~1.3

• Size of micelles characterized using DLS technique• PSt129-b-PVBT6 (Iav) data point omitted from plot as it

registered an Iav ~ 282nm with PDI of 1.0 (likely be due to dust or particulate) since scattering intensity MW∝ 2

• All other micelles have a 0.02 < PDI < 0.40 • Aggregation number of micelle may be a primary factor

for the relatively same Iav~ 45 nm between TP(6),TP(13) and TP(22) for core size exp.

• Further analysis recommended: • Static light scattering to obtain micellar MW

• TEM imaging for direct visual observation• An overall increase in micelle Iav as DP increases

CHCl3 @ 60°C

DMAc

+

Template Radical Polymerisation with VBA in CHCl3

Template Polymer Mn (g/mol)Daughter Polymer (PVBA)

Mn (g/mol) Mw (g/mol) Đ

PSt61-b-PVBT11 9000 - - -

PSt129-b-PVBT22 19100 318650 439291 1.19

PSt281-b-PVBT44 40600 - - -

Inspired by DNA’s replication process, McHale et al. employed a biomimetic approach to yield extremely high daughter polymer molecular weigh (MW) that is very well defined (Ð < 1.2) via free radical polymerisation[1]. The concept involves a templating effect that occurs in segregated micelles (nanoreactors). In this study, we seek to investigate the effect of micellar core size and its overall size on the final daughter polymer MW by template polymerising vinylbenzyl adenine (VBA) with poly(styrene(St)-b-vinylbenzyl thymine(VBT))

References Conclusion

• Micelle core size has no apparent effect on daughter polymer MW within the range explored• Micelle core size seems to have an impact on reaction conversion

• Higher micelle core size seems to increase reaction conversion • More investigation is required for micelle overall size effects due to absence of daughter polymer peaks (may be

due to insufficient initiator)• More characterisation analysis is encouraged as supplementing data e.g. SLS and Cryo-TEM

PSt-b-PVBT

PVBA

• Ultrahigh daughter polymer MW (>300 kg/mol) at ~17m

• Minimal deviation (4%) between the daughter polymer MW

• Peak intensity of daughter polymer increases with larger micellar cores/ heavier MW of TP

• Narrow dispersity for all daughter polymers (Ð < 1.2)

• No daughter polymer for TP(6)