waste not, want not: co2 (re)cycling in block polymer ... · 3 experimental section materials and...
TRANSCRIPT
1
Supporting Information for
Waste not, want not: CO2 (Re)cycling in Block Polymer Synthesis
Sumesh K. Raman, [a] Matthew G. Davidson, [b] Robert Raja,[c] Polly L. Arnold,[d]
Charlotte K. Williams*[a]
a Department of Chemistry, Oxford University, Oxford, OX1 3TA, UKb Department of Chemistry, University of Bath, Bath BA2 7AY, UK
c School of Chemistry, University of Southampton, Southampton SO17 1BJ, UKd EaStCHEM School of Chemistry, The University of Edinburgh, Edinburgh, EH9 3FJ, UK
Corresponding author email: [email protected]
DOI: 10.1002/anie.2016XXXXX
Materials and Methods................................................................................................................................3Synthesis of L-lactic acid O-carboxyanhydride (LLAOCA)......................................................................3Synthesis of L-phenyl lactic acid O-carboxyanhydride (LPheLAOCA) ....................................................4Representative polymerisation procedure for L-lactide-O-carboxyanhydride (LLAOCA) in tetrahydrofuran (THF) ................................................................................................................................4Representative polymerisation procedure of L-lactide-O-carboxyanhydride (LLAOCA) in cyclohexeneoxide (CHO)............................................................................................................................5Online reaction monitoring of LLAOCA/CHO polymerisation using ATR IR spectroscopy ...................5In situ reaction monitoring of LLAOCA/CHO polymerisation using 1H NMR spectroscopy...................5Scheme S1: Previously reported methods to prepare poly(ester-b-carbonate) AB or ABA type block copolymers. .................................................................................................................................................6Scheme S2: Ring opening polymerisation of LLAOCA using [LZn2(OAc)2]. ..........................................6Table S1: Selective polymerisation of LLAOCA and CHO to produce PLLA-b-PCHC...........................7Table S2: Polymerisation of other OCAs and epoxides .............................................................................8Table S3: DSC analysis of polymer samples ..............................................................................................8Characterisation of compounds...................................................................................................................9Figure S1: 1H NMR spectrum of the crude product from the ROP of LLAOCA using [LZn2(OAc)2] in THF (CDCl3, 400 MHz). ............................................................................................................................9Figure S2: 1H NMR spectrum of the isolated PLLA obtained from the ROP of LLAOCA using [LZn2(OAc)2] in THF, Table1, Entry 1. (CDCl3, 400 MHz).. ...................................................................9Figure S3: 1H{1H } NMR spectrum of the isolated PLLA, obtained from the ROP of LLAOCA using [LZn2(OAc)2] in THF, Table 1, Entry 1 (CDCl3, 500 MHz). ...................................................................10Figure S4: 13C{1H} NMR spectrum of the isolated PLLA, obtained from the ROP of LLAOCA using [LZn2(OAc)2] in THF (Table1, Entry 1) (CDCl3, 125 MHz). ..................................................................10Figure S6: 1H NMR spectrum of the isolated polymer PCHC-b-PLLA, (Table 1, Entry 7) (CDCl3, 500 MHz).11 Figure S7: 13C{1H} NMR spectrum of the isolated polymer PCHC-b-PLLA, (Table 1, Entry 7) (CDCl3, 125MHz).. .................................................................................................................................................12Figure S8: HMBC spectrum of PLLA-b-PCHC (Table 1, Entry 7). ........................................................12Figure S9: 1H DOSY NMR spectrum of PLLA-b-PCHC (Table 1, Entry 7)...........................................13
Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2019
2
Figure S10: 1H DOSY NMR spectrum of a physical mixtures of PLLA (Mn = 7000 g mol-1) and PCHC (Mn = 4000 g mol-1) (CDCl3, 400 MHz). ..................................................................................................13Figure S11: Plot of [LLAOCA] vs time. ..................................................................................................14Figure S12: Plot of Ln{[CHO]0/[CHO]t} vs time.....................................................................................14Figure S13: MALDI-ToF spectrum of the isolated PLLA........................................................................15Figure S14: MALDI-ToF spectrum of PLLA with a cyclohexyl acetate end group. ...............................16Figure S15: Illustrates the proposed initiation, propogation and termination pathways of LLAOCA polymerisation in THF using [LZn2(OAc)2] to produce cyclic and linear PLLA. ...................................17Figure S16: Illustrates the proposed initiation, propogation and CO2 recycling pathways of LLAOCA-CHO selective polymerisation to produce PLLA-b-PCHC. .....................................................................18Figure S17: DSC thermograms of PLLA-b-PCHC with different molar masses (Table S3). ..................19Figure S18: 1H NMR spectrum of isolated PLLA-b-PVCHC, with Mn = 6100 g mol-1 (CDCl3, 500 MHz). ........................................................................................................................................................19Figure S19: COSY NMR spectrum of PLLA-b-PVCHC, with Mn = 6100 g mol-1 (CDCl3, 500 MHz).20Figure S20: 13C{1H} NMR spectrum of PLLA-b-PVCHC, with Mn = 6100 g mol-1 (CDCl3, 125 MHz)....................................................................................................................................................................20Figure S21: HMBC spectrum of PLLA-b-PVCHC, with Mn = 6100 g mol-1 (CDCl3, 500 MHz). ..........21Figure S22: 1H DOSY NMR spectrum of PLLA-b-PVCHC with Mn = 6100 g mol-1 (CDCl3, 500 MHz)....................................................................................................................................................................21Figure S23: 1H NMR spectrum of PLPheLA-b-PCHC with Mn = 2500 g mol-1 (CDCl3, 500 MHz).......22Figure S24: COSY NMR spectrum of PLPheLA-b-PCHC with Mn = 2500 g mol-1(CDCl3, 125 MHz).22Figure S25: 13C{1H} NMR of PLPheLA-b-PCHC with Mn = 2500 g mol-1 (CDCl3, 125 MHz). ............23Figure S26: HMBC NMR spectrum of PLPheLA-b-PCHC with Mn = 2500 g mol-1 (CDCl3, 500 MHz)....................................................................................................................................................................23Figure S27: 1H DOSY spectrum of PLPheLA-b-PCHC with Mn = 2500 g mol-1(CDCl3, 500 MHz)......24Figure S28: SEC plots of PLLA-b-PVCHC and PLPheLA-b-PCHC ......................................................24Figure S29: DSC thermogram of PLLA-b-PVCHC with Mn = 6100 g mol-1 (Table S3, Entry 1). ..........25Figure S30: DSC thermogram of PLPheLA-b-PCHC (Table S3, Entry 2). .............................................25References.................................................................................................................................................26
3
Experimental Section
Materials and Methods
Lithium-L-lactate, triphosgene, and diphosgene were purchased from Acros Organics and used as
received. Cyclohexene oxide (CHO) was purchased from Acros Organics and dried, over CaH2,
distilled, degassed through freeze-pump-thaw cycles and stored under inert atmosphere (vinyl-
cyclohexene oxide was also purified in the same way). L-Phenyllactic acid was purchased from Sigma
Aldrich and used without further purification. Standard procedures were followed to dry THF, toluene,
dichloromethane, and chloroform-d1. The catalyst [LZn2(OAc)2],1 L-lactide O-carboxyanhydride
(LLAOCA),2 and L-phenyllactide O-carboxyanhydride (LPheLAOCA)3 were synthesized by the
previously published methods.
NMR spectra were recorded on a Bruker AV-400 or on a Bruker AV-500 instrument. All spectra were
processed using MestreNova or Topspin software. Elemental analyses were performed by Mr Stephen
Boyer at London Metropolitan University, North Campus, Holloway Road, London, N7. SEC analysis
was carried out on a Shimadzu LC-20AD instrument, equipped with a Refractive Index (RI) detector
and two PSS SDV 5 µm linear M columns. HPLC grade THF was used the eluent at 1.0 mL/min at 30
°C. Samples were passed through 0.2 µm PTFE filters prior to analysis. Monodisperse polystyrene
standards were used for calibration. Narrow MW polystyrene standards were used to calibrate the
instrument. All the DSC analyses were carried out in a Mettler Toledo instrument, with a heating-
cooling rate of 10 °C per minute, from -40 to 200 °C. MALDI ToF analyses were performed in a
MALDI Micro MX spectrometer, with dithranol as matrix (10 mg/mL) and sodium trifluoroacetic acid
(10 mg/mL) as an additive. The polymer (ca. 10 mg/mL), the matrix and the additive were mixed in a
ratio of 1/4/1 (v/v) in THF and 5 μL were spotted on the MALDI plate. All the analysis was performed
in positive reflectron mode.
Synthesis of L-lactic acid O-carboxyanhydride (LLAOCA)2
A 250 mL three necked round bottom flask fitted with a dropping funnel charged with L-lactic acid
lithium salt (3.50 g, 36.45 mmol) and anhydrous THF (50 mL). The resulting suspension was cooled to
0 °C. To this solution, triphosgene (3.97 g, 13.36 mmol) in anhydrous THF (15 mL) was slowly added,
using a dropping funnel. The reaction mixture was allowed to stir for 3 h at room temperature. After the
completion of the reaction the suspension became a clear solution. The THF was then removed to an
additional solvent trap connected to Schenk line under reduced pressure. The remaining white solid was
then redissolved in dichloromethane (20 mL) and filtered to another Schlenk flask using a cannula. The
solution containing LLAOCA was precipitated from anhydrous pentane (100 mL). The solvent was then
4
removed using a cannula filtration. The product was crystallized from a dichloromethane/pentane binary
mixture and sublimed before being used for polymerisation.
***CAUTION: Due to extremely high toxicity of phosgene, all reactions were conducted in an inert
atmosphere and in a well-ventilatted fume cupboard. The residual solvent and all contaminated
glassware was carefully quenched using an aq.NH3/ethanol (1:1) solution. This procedure was followed
for all other syntheses involving phosgene.
Isolated yield = 1.80 g, 44%1H NMR (CDCl3, 400 MHz): δ 5.16 (q, 1H, CH), 1.76 (d, 3H, CH3). 13C NMR (CDCl3, 100 MHz): δ
167.4, 148.1, 76.2, 16.6. HRMS (m/z): Calcd C4H4O4 requires 116.01 (M), found 117.0186 (M+H)+.
Synthesis of L-phenyllactide O-carboxyanhydride (LPheLAOCA)3
To a slurry of L-phenyl lactic acid (5.00 g, 30.10 mmol) and activated charcoal (0.25 g) in anhydrous
THF (30 mL), diphosgene (4.36 mL, 36.12 mmol) was added in portions. The resulting mixture was
then allowed to stir at room temperature for 8 hours. This solution was then filtered to a Schlenk flask,
through a plug of celite. The resulting clear solution was concentrated to ~10 mL and layered with
pentane (50 mL) resulting in the precipitation of LPheLAOCA as a white solid. The OCA was
crystallised from a THF/pentane mixture (v/v 5/50 mL). The isolated product was sublimed before
polymerisation. Isolated yield 3.75 g, 65%. 1H NMR (CDCl3, 500 MHz): δ 7.20-7.42 (m, 5H, Ar-H), 5.30 (t, 1H, CH, J = 5 Hz), 3.20-3.42 (m, 2H,
CH2). 13C NMR (CDCl3, 100 MHz): δ 167.4, 148.1, 76.2, 16.6. 13C {1H} NMR (CDCl3, 125 MHz):
166.4, 147.9, 131.6, 129.8, 129.3, 128.5, 80, 36.5. HRMS (m/z): Calcd C10H8O4 requires 192.04 (M),
found 193.0502 (M+H)+.
Representative polymerisation procedure for L-lactide-O-carboxyanhydride (LLAOCA) in
tetrahydrofuran (THF)
[LZn2(OAc)2] (0.004 g, 0.005 mmol), LLAOCA (0.29 g, 2.50 mmol) were weighed to a 15 mL Schlenk
tube, equipped with a magnetic stirring bar, and then tightly closed. The reaction mixture was then
vigorously stirred, at 80 °C, for 16 h. At the end of the reaction an aliquot was taken for 1H NMR
spectroscopy to estimate the conversion and the product distribution. The remaining crude polymer
solution was diluted with dichloromethane (2 mL) and then precipitated using cold pentane, the
precipitate was filtered and the product dried under vacuum at 40 °C for 48 h.
5
Representative polymerisation procedure of L-lactide-O-carboxyanhydride (LLAOCA) in
cyclohexeneoxide (CHO)
[LZn2(OAc)2] (0.004 g, 0.005 mmol), LLAOCA (0.29 g, 2.50 mmol), and cyclohexene oxide (1.97 g,
19.47 mmol) were weighed to a 15 mL Schlenk tube, equipped with a magnetic stirring bar, and then
tightly closed. The reaction mixture was then vigorously stirred at 80 °C for 16 h. At the end of the
reaction an aliquot was taken for 1H NMR spectroscopy to estimate the conversion and the product
distribution. The remaining crude polymer solution was diluted with dichloromethane (2 mL) and the
polymer by adding excess cold pentane. The solution was filtered and the product dried under vacuum
at 40 °C for 48 h.
Online reaction monitoring of LLAOCA/CHO polymerisation using ATR IR spectroscopy
A 50 mL three necked Schlenk tube was equipped with a Mettler-Toledo ReactIR 4000 spectrometer,
with a MCT detector, and a silver halide DiComp probe. To a pre-connected and vacuum dried three
necked flask, LLAOCA (0.90 g, 7.76 mmol), [LZn2(OAc)2] (0.012 g, 0.016 mmol) and CHO (6.20 mL,
61.42 mmol). The reaction mixture was immediately immersed in a in a pre-heated oil bath at 80 °C.
The polymerisation was then monitored for 54 h. IR resonances corresponding to LLAOCA, PLLA,
PCHC and CO2 were monitored.
In situ reaction monitoring of LLAOCA/CHO polymerisation using 1H NMR spectroscopy
[LZn2(OAc)2] (0.0025 g, 0.0031 mmol), LLAOCA (0.18 g, 1.57 mmol), cyclohexene oxide (0.67 mL,
6.90 mmol), THF-d8 (0.51 mL) and mesitylene (0.044 mL) were weighed to a vial and immediately
transferred in to a 1 mL J Young NMR tube and tightly sealed. The tube was then inserted to a
previously shimmed and heated NMR instrument (Bruker 500 MHz). The first 1H NMR spectrum of
this reaction mixture was recorded after 2 minutes at 80 °C. The polymerisation was monitored by
measuring 1H NMR spectra at regular time intervals over 53 h. The conversion was determined by
comparison of resonances assigned to LLAOCA (1.76 ppm), PLLA (1.56 ppm), PCHC (4.92–4.18
ppm), and trans-CHC (4.02 ppm). Mesitylene (6.57 ppm) was used as an internal standard.
6
PLA-b-PCHC Syntheses
+ CO2
OO
OO
H O
OO
OO
OO
HOO
H OO
HO
O
OO
OO
O
RO O
OO
Hm n
HO
O
OO
OO
O
Poly(cyclohexene carbonate-b-L-lactide)
O
Ph+ CO2 O
PhO
O
OCo(Salen)
PhX O
PhO
O
O
PhX
OO
OO
Poly(styrene carbonate-b-lactide)
NN
OOCo
XtBu
tBu tBu
NX
NtBu
O
tBu
NZn
2 3
N
N
4
A.
B.
C.
H
HH
H
Zn ZnNN
tBu
O
N N
tBu
O
OCOCF3
F3COCO
1
NY
N OP
PO
iPr iPr
iPriPr
N(SiHMe2)2
5
Conditions: i) 1, CO2 = 1 bar; ii) 2, L-lactide
Conditions: i) 3/BnOH; ii) 3/BnOH, L-lactide
i
i ii
ii
Poly(L-lactide-b-cyclohexene carbonate-b-L-lactide)
Conditions: i) 4 ; ii) 5, H2O, Lactide
i ii
n n m
mRO
n n mm
Scheme S1: Previously reported methods to prepare poly(ester-b-carbonate) AB or ABA type block copolymers.4-6
O
CH3
OO
O
OO
CH3
n
PLLALLAOCA
+ n CO2n
Scheme S2: Ring opening polymerisation of LLAOCA using [LZn2(OAc)2].
7
Table S1: Selective polymerisation of LLAOCA and CHO to produce PLLA-b-PCHC [a]
OO
OO
CH3
OO
O
OO
CH3
O
+[LZn2(OAc)2]
mn
OO
O
+
Entry Time(h)
LLAOCAConv (%) [b]
PCHC(%) [c]
trans-CHC(%) [d] Polymer Mn,exp (Mn,calc)
g mol-1 [e] Đ [e] DP [f]
PLLA/PCHC1 [g] 16 97 - - PLLA 4300 (17,500) 1.15 101/-2 [h] 16 >99 0 0 PLLA 4100 (18,000) 1.98 97/-3 0.16 23 0 0 PLLA 2800 (4100) 1.66 38/04 1 >99 8 0 PLLA-b-PCHC 4600 1.33 56/65 8 >99 17 1 PLLA-b-PCHC 7600 1.30 78/146 16 >99 53 1 PLLA-b-PCHC 8400 1.24 76/207 24 >99 71 2 PLLA-b-PCHC 11000 1.54 88/338 48 >99 91 9 PLLA-b-PCHC 13600 1.45 90/35
[a] All the polymerisations were conducted in a 15 mL Schlenk tube in THF, THF-CHO mixture or in
neat CHO, [LLAOCA] = 1.25 M, [LZn2(OAc)2] = 2.5 mM. [b] Determined by 1H NMR spectroscopy
from the normalized integrals for resonance from LLAOCA (1.76 ppm) and PLLA (1.56 ppm). [c]
Determined by 1H NMR spectroscopy of crude polymerisation sample from the normalized integrals for
resonance from PLLA (1.56 ppm) and PCHC (4.92 – 4.18 ppm). [d] trans-CHC = cyclohexene
carbonate, determined by 1H NMR spectroscopy from the normalized integrals for resonance from
PLLA (1.56 ppm) and trans-CHC (4.02 ppm). [e] Determined by SEC in THF, calibrated with narrow
polydisperse polystyrene standards. Mn,calc values are reported only for PLLA using Mn,calc = [Degree of
Polymerisation x 72]/2. Note equivalent calculations for block polymers are not considered informative
since it is not possible to properly compare experimental and calculated values as the block polymer
composition changes with conversion. [f] DP is degree of polymerisation and is determined using 1H
NMR spectroscopy by comparing the relative intensity of integrals from PLLA (1.56 ppm) and PCHC
(4.92 – 4.18 ppm) (using the isolated polymer sample). [g] Polymerisation conducted in THF,
[LZn2(OAc)2]/[LLAOCA] = 500, [LLAOCA] = 1.25 M. [h] Polymerisation conducted in THF-CHO
mixture with [LZn2(OAc)2]/[LLAOCA]/[CHO] = 1/500/500, [LLAOCA] = 1.25 M in THF-CHO
mixture.
8
Table S2: Polymerisation of other OCAs and epoxides [a]
OO
OO
R
O
O O
O
O
R1 R2
O
+
R
R1 R2
O=
O O
=
VCHO CHO
LLAOCA LPheLAOCA
R1
R2 mn
O O
O
O
R
O O
O
O
CH3
O O
O
O
Ph
Poly(ester-b-carbonate)
Entry Epoxide OCA OCAConv (%) [b]
PC(%) [c]
CC(%) [d] Polymer Mn,exp
g mol-1 [e] Đ [e]
1 VCHO LLA >99 >99 0 PLLA-b-PVCHC 6100 2.182 CHO LPheLLA >99 68 13 PLPheLA-b-PCHC 2500 1.31
[a] All the polymerisations were conducted in a 15 mL Schlenk tube, neat epoxide, [OCA] = 1.25 M, 48
h. VCHO = 4-vinyl 1,2-cyclohexene oxide. [b] Determined by 1H NMR spectroscopy from the
normalized integrals for resonance from LLAOCA (1.76 ppm) and PLLA (1.56 ppm). [c] PC =
polycarbonate, determined by 1H NMR spectroscopy from the normalized integrals for resonance from
PLLA (1.56 ppm) and PCHC (4.92–4.18 ppm). [d] CC = cyclic carbonate, determined by 1H NMR
spectroscopy from the normalized integrals for resonance from PLLA (1.56 ppm) and trans-CHC (4.02
ppm). [e] Determined by SEC, in THF, calibrated with narrow dispersity polystyrene standards.
Table S3: DSC analysis of polymer samples
Entry Polymer Mn,expg mol-1 [a] Đ[a] Tg, exp °C [b] Tg, calc °C [c] Ester (W1)/Carbonate (W2)
Wt % [d]
1 PLLA 4300 1.15 57 57 100/02 PLLA-b-PCHC 7600 1.30 61 66 74/263 PLLA-b-PCHC 8400 1.26 69 69 66/344 PLLA-b-PCHC 11000 1.54 73 72 60/405 PLLA-b-PCHC 13500 1.45 78 77 52/486 [e] PLLA-b-PVCHC 6100 2.18 74 - -7 PLPheLA 4000 1.13 33 33 100/08 PLPheLA-b-PCHC 2500 1.31 32 45 62/38
[a] Determined by SEC in THF, calibrated with narrow dispersity polystyrene standards. [b]
Determined by DSC at a heating rate of 10 °C per minute, from -40 to 200 °C. [c] Calculated Tg, calc
determined using the Fox-Flory equation (1/Tg) = (W1/Tg,1) + (W2/Tg,2), where W1 and W2 are the
weight fractions of ester and carbonate blocks, Tg,1 and Tg,2 are the glass transition temperatures of
PLLA (57 oC) and PCHC (122 °C). [d] Determined by 1H NMR spectroscopy. [e] The sample could not
be characterised due to the overlap of methine resonances attributed to PLLA and PVCHC.
Characterisation of compounds
9
1O
CH3
2
O
2
1
* *
1.01.21.41.61.82.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.05.25.45.65.86.0f1 (ppm)
0.11
3.00
0.19
0.97
1.56
1.70
1.82
3.72
5.15
Figure S1: 1H NMR spectrum of the crude product from the ROP of LLAOCA using [LZn2(OAc)2] in THF (CDCl3, 400 MHz). * THF.
0.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.05.25.45.65.8f1 (ppm)
3.13
0.01
0.02
1.00
0.88
1.01
1.22
1.59
2.12
3.49
4.36
5.17
OHO
CH3
O5
6O
CH3
O3
4
5
3
4, 6
CH3
O
OH
1
2
2 1*
Figure S2: 1H NMR spectrum of the isolated PLLA obtained from the ROP of LLAOCA using [LZn2(OAc)2] in THF (Table 1, Entry 1) (CDCl3, 400 MHz). * Solvent.
10
4.804.854.904.955.005.055.105.155.205.255.305.355.405.455.505.55f1 (ppm)
5.16
O
OCH3H
n
1
1
Figure S3: 1H{1H } NMR spectrum of the isolated PLLA, obtained from the ROP of LLAOCA using [LZn2(OAc)2] in THF (Table 1, Entry 1) (CDCl3, 500 MHz).
0102030405060708090100110120130140150160170180190200f1 (ppm)
16.7
7
69.1
4
77.1
6
169.
74
O
CH3
O1
2
3
2
1
3
Figure S4: 13C{1H} NMR spectrum of the isolated PLLA, obtained from the ROP of LLAOCA using [LZn2(OAc)2] in THF (Table1, Entry 1) (CDCl3, 125 MHz).
11
(a) (b)
1000 10000 100000
Molecular mass, Mn (g mol-1)
Mn = 4300 (Ð = 1.15)
100 1000 10000 100000 1000000
Molecular mass, Mn (g mol-1)
Mn = 4100 (Ð = 1.98)
Figure S5: SEC analysis of polymers (a) PLLA from LLAOCA ROP in THF (Table 1, Entry 1); (b) PLLA from LLAOCA ROP in THF and CHO (Table 1, Entry 2).
3O
O
CH3
4
OO
O55O
6
77
6
O
O
8
6
77
6
8O
PCHCend group
PCHC-PLLAjunction
1O
CH3
2
O
PLLA
O
O
9
6
77
6
10HO
1.01.21.41.61.82.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.05.25.45.6f1 (ppm)
1.34
1.47
1.58
1.71
2.10
3.57
4.41
4.67
4.84
5.17
767
6
2, 4
109
8
5
1
3
PCHC
Figure S6: 1H NMR spectrum of the isolated polymer PCHC-b-PLLA. (Table 1, Entry 7) (CDCl3, 500 MHz).
12
3 1
OO
CH3
2
O4
O
O55
6
77
6 2
3
1
6 74
102030405060708090100110120130140150160170180f1 (ppm)
16.7
0
23.1
5
29.7
7
69.0
771
.81
74.6
776
.59
77.1
6
153.
3015
3.87
154.
32
169.
66
5
* *
Figure S7: 13C{1H} NMR spectrum of the isolated polymer PCHC-b-PLLA, (Table 1, Entry 7) (CDCl3, 125MHz). * PLLA-b-PCHC junction units.
3
4
(3-4)
Figure S8: HMBC spectrum of PLLA-b-PCHC (Table 1, Entry 7).
13
Figure S9: 1H DOSY NMR spectrum of PLLA-b-PCHC (Table 1, Entry 7).
Figure S10: 1H DOSY NMR spectrum of a physical mixtures of PLLA (Mn = 7000 g mol-1) and PCHC (Mn = 4000 g mol-1) (CDCl3, 400 MHz).
14
0 2000 4000 6000 8000 10000 12000
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
[LLA
OCA
] M
Time (s)
kobs = 1.08 x 10-4 s-1
R2 = 0.9980
Figure S11: Plot of [LLAOCA] vs time. Reaction conditions: [LLAOCA]0 = 1.25 M, [CHO]0 = 5.5 M, [LZn2(OAc)2]/[LLAOCA]= 1/500, 80 °C. The linear fit indicates zero order reaction in [LLAOCA].
0.0 4.0104 8.0104 1.2105 1.61050.00
0.02
0.04
0.06
0.08
0.10
0.12kobs = 1.04 x 10-6 s-1
R2 = 0.9923
Ln([
CHO
] 0/[C
HO
] t)
Time (s)
Figure S12: Plot of Ln{[CHO]0/[CHO]t} vs time. [LLAOCA]0 = 1.25 M, [CHO]0 = 5.5 M, [LZn2(OAc)2]/[LLAOCA]= 1/500, 80 °C. The linear fit indicates a first order dependence in [CHO], with a kobs = 1.04 х 10-6 s-1. Note that the curvature indicates relatively slow initiation.
15
OO
O
OOO
O
O
OO
O
O
OO
OH
O
O
OHONa
Na
n
nA
B
Figure S13: MALDI-ToF spectrum of the isolated PLLA. Reaction conditions: [LLAOCA]0 = 1.25 M, [LZn2(OAc)2]/[LLAOCA]= 1/500, 80 °C (Table 1, Entry 1). Series A has a repeat unit m/z = 90.02 (lactic acid + (72)n (PLLA) + 22.98 (Na+), where n = 11-25. Series B follows m/z = (72)n (PLLA) + 22.98 (Na+), where n = 12-26.
16
O
CH3
O
O
CH3
O OO
CH3
HONa+
Figure S14: MALDI-ToF spectrum of PLLA with a cyclohexyl acetate end group. Reaction conditions: [LLAOCA]0 = 1.25 M, [LZn2(OAc)2]/[LLAOCA] = 1/500, 80 °C, 10 min (Table 1, Entry 3). The series follows m/z = 157.01 (cyclohexyl acetate) + (72)n (PLLA) + 22.98 (Na+), where n = 9-37.
17
A. Initiation
Zn ZnO O
OOZn ZnO O
O OO
OO O
Zn ZnO O
OO
OO
OO
Zn ZnO O
O O
OO
Zn ZnO O
O O
OO
ZnZnOO
OO
O
O
O O
OO
B. Propagation
C. Termination - Back-biting to form the cyclic polymer
O
O OZn Zn
D. Termination - Hydrolysis of end-group
OO
O
O CO
O
OO
O
O
nn C
O
O
O OO
OO
O
O
Zn ZnO O
OO
OO
O
OOO
O
O
OO
O
O
OO
OH
O
O
OHO
n
n
+
O
O OZn Zn
O OO
OO
O
O
H2O
n
n
+HO
O
O
O OZn Zn
O OO
OO
O
O
n
Figure S15: Illustrates the proposed initiation, propogation and termination pathways of LLAOCA polymerisation in THF using [LZn2(OAc)2] to produce cyclic and linear PLLA. Note that for clarity the ligand is not shown.
18
A. Initiation
Zn ZnO O
OOZn ZnO O
OO
O
O
Zn ZnO O
OO
O
Zn ZnO O
O OO
OOO O
Zn ZnO O
OO
OO
O
OO
Zn ZnO O
O O
O
OO
Zn ZnO O
O O
O
OO
ZnZnOO
OO
O
O
O O
O
OO
B. Propagation
O O
O OZn Zn
C. CO2 recycling - CO2 insertion
O O
O OZn Zn
O OZn Zn
OO
OO
D. CO2 recycling - CHO insertion
O OZn Zn
OO
OO
Zn ZnO O
OO
OO
O
PLA
Zn ZnO O
OO
OO
O
PLA
OO
O
O
CO
O
OO
O
O
n
n CO
O
n CO
O
O
PLA
PLAPLA
PLA
Figure S16: Illustrates the proposed initiation, propogation and CO2 recycling pathways of LLAOCA-CHO selective polymerisation to produce PLLA-b-PCHC.
19
0 50 100 150 200
0
5
10
B
C
D
E: Tg = 78 oC, Mn = 13500 g mol-1
D: Tg = 73 oC, Mn = 11000 g mol-1
C: Tg = 69 oC, Mn = 8400 g mol-1
B: Tg = 61 oC, Mn = 7600 g mol-1
Exo
Temperature (oC)
E
Figure S17: DSC thermograms of PLLA-b-PCHC with different molar masses (Table S3).
OO
CH3
O3
4O
CH3
O1
2
O
O5
67
1110
10
11, 3 5
6
9
8
7
6
0.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.84.04.24.44.64.85.05.25.45.65.86.06.26.4f1 (ppm)
1.54
1.55
1.81
2.14
2.40
4.74
4.86
5.00
5.04
5.07
5.14
5.73
1
2, 4
6, 8, 9
Figure S18: 1H NMR spectrum of isolated PLLA-b-PVCHC, with Mn = 6100 g mol-1 (CDCl3, 500 MHz).
20
Figure S19: COSY NMR spectrum of PLLA-b-PVCHC, with Mn = 6100 g mol-1 (CDCl3, 500 MHz).
2 1
OO
CH3
3
O56
7
8 910
4O
O
11 12
3
2
1
4
11
125, 6
10
97, 8
102030405060708090100110120130140150160170180f1 (ppm)
16.6
816
.78
20.5
525
.29
26.1
229
.45
31.6
434
.88
39.1
139
.13
66.7
069
.02
71.4
571
.77
73.3
973
.65
74.1
077
.42
113.
98
140.
8714
1.52
153.
2415
3.30
153.
3615
3.42
169.
4216
9.56
Figure S20: 13C{1H} NMR spectrum of PLLA-b-PVCHC, with Mn = 6100 g mol-1 (CDCl3, 125 MHz).
21
11, 2
(2-4)
4
Figure S21: HMBC spectrum of PLLA-b-PVCHC, with Mn = 6100 g mol-1 (CDCl3, 500 MHz).
Figure S22: 1H DOSY NMR spectrum of PLLA-b-PVCHC with Mn = 6100 g mol-1 (CDCl3, 500 MHz).
22
6O
OO
O
O77O
8
99
8
O
O
10
8
99
8
10O
PCHCend group
PCHC-PLPheLAjunction
1O
2
O
PLPheLA
O
O
11
8
99
8
12HO
34
5
43
34
5
43
2
1
6
3, 4, 5
*
8
9
9
117
10
12
2
8
0.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.0f1 (ppm)
1.31
1.72
2.07
3.07
3.18
3.59
4.44
4.69
4.85
5.11
5.29
7.13
7.14
7.26
PCHC
Figure S23: 1H NMR spectrum of PLPheLA-b-PCHC with Mn = 2500 g mol-1 (CDCl3, 500 MHz).
Figure S24: COSY NMR spectrum of PLPheLA-b-PCHC) with Mn = 2500 g mol-1(CDCl3, 125 MHz).
23
21
OO
O8
O
O910
11
1212
11
45
67
65 3
1
89, 10
3
2
6
5
7
102030405060708090100110120130140150160170180f1 (ppm)
22.9
623
.92
29.7
032
.63
36.9
4
73.2
8
77.1
6
127.
1712
8.56
129.
4012
9.45
135.
47
154.
35
168.
13
4
11, 12
Figure S25: 13C{1H} NMR of PLPheLA-b-PCHC with Mn = 2500 g mol-1 (CDCl3, 125 MHz).
2
8
(2-8)
Figure S26: HMBC NMR spectrum of PLPheLA-b-PCHC with Mn = 2500 g mol-1 (CDCl3, 500 MHz).
24
Figure S27: 1H DOSY spectrum of PLPheLA-b-PCHC with Mn = 2500 g mol-1(CDCl3, 500 MHz).
Fi
(a) (b)
100 1000 10000 100000 1000000
Molecular mass, Mn (g mol-1)
Mn = 6100 (Ð = 2.18)
100 1000 10000 100000 1000000
Molecular mass, Mn (g mol-1)
Mn = 2500 (Ð =1.29)
gure S28: SEC plots of polymers (a) PLLA-b-PVCHC obtained by the reaction of LLAOCA and VCHO (Table S2, Entry 1); (b) PLPheLA-b-PCHC obtained by the reaction of LPhLAOCA and CHO (Table S2, Entry 2).
25
0 50 100 150 200-2.0
-1.5
-1.0
-0.5
0.0
Exo
Temperature(oC)
Tg = 74 oC, Mn = 6100 g mol-1
Figure S29: DSC thermogram of PLLA-b-PVCHC with Mn = 6100 g mol-1 (Table S3, Entry 1).
0 50 100 150 200-2.0
-1.5
-1.0
-0.5
0.0
Exo
Temperature (oC)
Tg = 32 oC, Mn = 2500 g mol-1
Figure S30: DSC thermogram of PLPheLA-b-PCHC (Table S3, Entry 2).
26
References
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Macromolecules, 2015, 48, 3247-3256.6. G.-P. Wu, D. J. Darensbourg and X.-B. Lu, J. Am. Chem. Soc., 2012, 134, 17739-17745.