Supporting Information forZi Wang and Stephen L. Craig* Department of Chemistry, Duke University, Durham, North Carolina 27708 *To whom correspondence should be addressed. Phone: (919)

S1

Supporting Information for

Stereochemical effects on the mechanochemical scission of furan-

maleimide Diels-Alder adducts

Zi Wang and Stephen L. Craig*

Department of Chemistry, Duke University, Durham, North Carolina 27708

*To whom correspondence should be addressed. Phone: (919) 660-1538.

Fax: (919) 660-1605. Email: [email protected]

Table of Contents

1. General procedure .................................................................................................. S2

2. Synthesis .................................................................................................................. S3

2.1 Small molecule synthesis ...................................................................................... S3

2.2 Polymer synthesis .................................................................................................. S5

3. Thermal degradation of P1 and P2 ....................................................................... S8

4. Sonication .............................................................................................................. S12

4.1 2-hour sonication experiment ...................................................................... S13

4.2 Ring opening determination and Scission Cycle calculation. ................... S16

4.3 Sonication experiments to determine 𝚽i .................................................... S17

4.4 Mn,4h measurements ...................................................................................... S23

5. Calculation of transition state geometry ............................................................. S25

6. Modeling of the activation lengths ....................................................................... S34

7. 1H and 13C NMR ................................................................................................... S35

Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2019

S2

8. References .............................................................................................................. S44

1. General procedure Solvents were purchased from VWR. Dichloromethane, toluene and THF were purified

with an Innovative Technology purification system. Maleic anhydride, furan, ethanolamine,

glutaric acid and N,N′-diisopropylcarbodiimide (DIC) were purchased from Sigma-Aldrich.

4-(dimethylamino)pyridinium-4-toluenesulfonate (DPTS) was synthesized following the

methodology of Moore and Stupp.1

1H and 13C NMR were collected on the Varian 400 and Bruker 500 MHz spectrometer

with reference to solvent peak CDCl3 (1H δ = 7.26 and 13C δ = 77.16) or DMSO-d6 (1H δ

= 2.50 and 13C δ = 39.52). All chemical shifts are given in ppm (δ) and coupling constants

(J) in Hz as singlet (s), doublet (d), triplet (t), quartet (q), multiplet (m), or broad (br).

Column (flash) chromatography was performed using Silicycle F60 (230 - 400 mesh) silica

gel.

Gel permeation chromatography (GPC) was performed with an Agilent 1260 Infinity

LC system, using 2 in series Agilent PLgel mixed-C columns (105 Å, 7.5x300 mm, 5 µm,

part number PL1110-6500) at room temperature at a flow rate of 1.0 mL/min in THF.

Molecular weights were calculated using an in line Wyatt miniDAWN TREOS multi-angle

light scattering detector with Wyatt Optilab T-rEX refractive index detector. Based on

injections with known injected mass and assuming 100% mass recovery, the refractive

index increment (dn/dc) values were calculated.

S3

2. Synthesis

2.1 Small molecule synthesis

3a,4,7,7a-Tetrahydro-4,7-epoxyisobenzofuran-1,3-dione (1)

Maleic anhydride (19.61 g, 0.2 mol) was added in 200 mL toluene, then furan (30 mL) was

added dropwise over 30 min. The solution was stirred at room temperature for 36 h. White

precipitate formed. Keep the suspended solution at 5°C for 2 h. Filtrate and wash the white

powder with cold ethyl ether for 3 times. Compound 1 (18.02 g) was obtained without

further purification. Yield: 54%. 1H NMR (400 MHz, DMSO-d6) δ 6.51 (s, 2H), 5.09 (s, 2H), 3.38 (s, 2H); 13C NMR (400 MHz, DMSO-d6) δ 176.92, 136.88, 80.70, 47.56.

3a,4,7,7a-Tetrahydro-2-(2-hydroxyethyl)-4,7-epoxy-1H-isoindole-1,3(2H)-dione (2)

Compound 1 (5.00 g, 30.1 mmol) was suspended in 12 mL MeOH under argon.

Ethanolamine (1.82 mL, 30.1 mmol) was added dropwise at room temperature and the

solution turned into deep orange color. The solution was refluxed at 70 °C for 20 h and

then cool down to room temperature. Then keep the solution at -4 °C for 4 h to precipitate

the crude product. White powder was filtrated out and washed by cold ethyl ether for 3

times. Compound 2 (3.38 g) was obtained without further purification. Yield: 55%. 1H NMR (400 MHz, DMSO-d6) δ 6.51 (s, 2H), 5.08 (s, 2H), 4.75 (s, 1H), 3.37 (s, 4H), 2.89

(s, 2H); 13C NMR (400 MHz, DMSO-d6) δ 176.92, 136.88, 80.70, 57.69, 47.56, 41.03.

N-(2-Hydroxyethyl)maleimide (3)

Compound 2 (3.38 g, 16.15 mol) was suspended in 50 mL toluene and the solution was

refluxed at 120 °C overnight. Cool the solution to room temperature and put it in freezer

O+ O

O

O

toluener.t

O

O

O

O

H2NOH

MeOH70

O toluenereflux

NOH

O

O1 2 3

N

O

O

OH

S4

for 4 h. Filter the white crystal out and wash with cold ethyl ether for 3 times. Compound

3 (1.87 g) was obtained without further purification. Yield: 82%. 1H NMR (500 MHz, DMSO-d6) δ 7.01 (s, 2H), 4.77 (s, 1H), 3.45 (s, 4H); 13C NMR (400 MHz, DMSO-d6) δ 171.50, 134.81, 58.36, 40.33.

(3aR,4S,7R,7aS)-rel-3a,4,7,7a-Tetrahydro-2-(2-hydroxyethyl)-4-(hydroxymethyl)-

4,7-epoxy-1H-isoindole-1,3(2H)-dione (4)

Compound 3 (1.86 g, 13.17 mmol) was suspended in 20 mL toluene, and furfuryl alcohol

(1.15 mL, 13.27 mmol) was added dropwise under stirring. The temperature was then

raised to 80 °C to fully dissolve reactants and the solution was refluxed at 80 °C overnight.

White precipitate formed at the bottom of the flask as the temperature cooled down to room

temperature. Filter the crude products out and wash with cold ethyl ether for 3 times.

Compound 4 (2.82 g) was obtained without further purification. Yield: 90%. HRMS-ESI

(m/z): calcd for C11H13NO5 [M+Na]+, 262.1; observed, 262.0. 1H NMR (400 MHz, DMSO-d6) δ 6.48 (m, 2H), 5.04 (s, 1H), 4.91 (m, 1H), 4.75 (m,1H),

3.99 (dd, J = 12.8, 6.0 Hz, 1H), 3.65 (dd, J = 12.8, 5.6 Hz, 1H), 3.37 (m, 4H), 3.00 (d, J =

6.4 Hz, 1H), 2.84 (d, J = 6.4 Hz, 1H). 13C NMR (400 MHz, DMSO-d6) δ 176.82, 175.37, 138.53, 136.88, 92.06, 80.59, 59.36,

57.69, 50.39, 48.20, 40.97.

NOH

O

O3

+O

OHtoluene

80oC overnight

O

HO

NOH

H

O

OH

4

NOH

O

O

3

+O

OH

O

HO

NOH

H

O

OH

4

+

O

HON

OH

HH

O

O

5

r.t 7 days2-butanone

1:3 endoexo

S5

(3aR,4R,7S,7aS)-rel-3a,4,7,7a-Tetrahydro-2-(2-hydroxyethyl)-4-(hydroxymethyl)-

4,7-epoxy-1H-isoindole-1,3(2H)-dione (5)

Compound 3 (5.47 g, 38.59 mmol) was dissolved in 40 mL 2-butanone, and furfuryl

alcohol (3.34 mL, 38.59 mmol) was added dropwise under stirring. The lightly yellow

solution was stirred at room temperature for 7 days. Evaporate the solvent away and the

crude products were purified by silica gel column chromatography (gradient elution: 100%

EtOAc to EtOAc : MeOH = 19:1). The ratio of two stereoisomers was determined to be

exo : endo = 1:3 and pure endo isomer compound 5 (792 mg) was obtained after the

chromatography. HRMS-ESI (m/z): calcd for C11H13NO5 [M+Na]+, 262.1; observed, 262.1. 1H NMR (400 MHz, DMSO-d6) δ 6.35 (dd, J = 5.6, 1.6 Hz, 1H), 6.24 (d, J = 5.6 Hz, 1H),

5.19 (dd, J = 5.6, 1.6 Hz, 1H), 5.13 (t, J = 6.0 Hz, 1H), 3.96 (dd, J = 7.2, 5.6 Hz, 1H), 3.87

(dd, J = 12.8 ,6.0 Hz, 1H), 3.59 (m, 2H), 3.35 (m, 2H), 3.26 (m, 2H). 13C NMR (400 MHz, DMSO-d6) δ 175.74, 175.52, 135.70, 135.43, 92.74, 78.91, 59.99,

57.53, 48.03, 45.55, 40.56.

(1R, 2S)-rel-3,3-Dichloro-1,2-cyclopropanedimethanol (6)

Compound 6 was synthesized following the methodology of Pustovit and Rozhenko.2 1H NMR (400 MHz, CDCl3) δ 4.09 (m, 2H), 3.69 (m, 2H), 2.28 (t, 2H), 2.07(m, 2H). 13C NMR (400 MHz, CDCl3) δ 58.74, 33.96.

2.2 Polymer synthesis

ClCl

OHHO

ClCl

OHHO HO OH

O O+ + DIC, DPTS

DCM

O

HO

NOH

H

O

OH

O

O

O

NH

O

O

H O

Cl Cl

O O

O

O

O( )( )m n

P1

S6

Compound 4 (35.9 mg, 0.15 mmol), gDCC (205.2 mg, 1.20 mmol), glutaric acid (178.4

mg, 1.35 mmol), and DPTS (141.3 mg, 0.48 mmol) were dried under high vacuum in a

40 °C oil bath for 24 hours. Collect all four reagents in a 25 mL round bottom flask and

nitrogen purge for 20 minutes. Then 3.8 mL anhydrous DCM was added dropwise using

syringe. Heat the solution to 40 °C to fully dissolve reactants and subsequently cool the

solution to room temperature. Next, DIC (0.56 mL, 3.6 mmol) was added dropwise to

initiate the polymerization. The solution was kept at room temperature for 2-3 days to yield

polymers with different molecular weights. Precipitate the polymer in MeOH and

redissolve it with DCM alternately for 3 times. A light yellow polymer P1 (324 mg) was

obtained. The exo monomer ratio was determined by 500 Hz 1H NMR. 1H NMR (500 MHz, CDCl3) δ 6.59 (d, J = 4.5 Hz, 1H), 6.46 (d, J = 4.5 Hz, 1H), 5.31 (m,

1H), 4.93 (d, J = 12.5 Hz, 1H), 4.48 (d, J = 12.5 Hz, 1H), 4.25 (s, 15H), 3.77 (m, 2H), 3.03

(d, J = 6.0 Hz, 1H), 2.95 (d, J = 6.0 Hz, 1H), 2.46 (m, 15H), 2.14 (s, 7H), 2.01 (m, 7H).

Table S1. % exo monomer, Mn, PDI, and dn/dc values of three characterized P1 1-3. The

average dn/dc of P1 (0.067) is used for the 𝛷i analysis of P1 1-3.

exo monomer

ratio (mol%)

Mn (kDa) PDI dn/dc

P1-1 20 77 1.27 0.068

P1-2 21 160 1.15 0.065

P1-3 20 220 1.10 0.068

ClCl

OHHO HO OH

O O+ + DIC, DPTS

DCM

P2

O

HON

OH

HH

O

O

O

ON

HH

O

O

O

Cl Cl

O O)( )m n

O

OO

O(

S7

Compound 5 (47.9 mg, 0.20 mmol), gDCC (239.4 mg, 1.40 mmol), glutaric acid (211.4

mg, 1.60 mmol), and DPTS (188.4 mg, 0.64 mmol) were dried under high vacuum in 40 °C

oil bath for 24 hours. Collect all four reagents in a 25 mL round bottom flask and nitrogen

purge for 20 minutes. Then 4.6 mL anhydrous DCM was added dropwise using syringe.

Heat the solution to 40 °C to fully dissolve reactants and subsequently cool the solution to

room temperature. Next, DIC (0.74 mL, 4.8 mmol) was added dropwise to initiate the

polymerization. The solution was kept at room temperature for 2-3 days to yield polymers

with different molecular weights. Precipitate the polymer in MeOH and redissolve it with

DCM alternately for 3 times. A lightly yellow polymer P2 (386 mg) was obtained. The

endo monomer ratio was determined by 500 Hz 1H NMR. 1H NMR (500 MHz, CDCl3) δ 6.47 (d, J = 5.0 Hz, 1H), 6.34 (d, J = 5.0 Hz, 1H), 5.33 (m,

1H), 4.89 (d, J = 12.5 Hz, 1H), 4.62 (d, J = 12.5 Hz, 1H), 4.25 (s, 15H), 4.13 (s, 2H), 3.69

(t, J = 6.0 Hz, 1H), 3.62 (s, 2H), 3.43 (d, J = 7.5 Hz, 1H), 2.47 (m, 16H), 2.14 (m, 7H), 2.01

(m, 8H).

Table S2. % endo monomer, Mn, PDI, and dn/dc values of three characterized P2 1-3. The

average dn/dc of P2 (0.066) is used for the 𝛷i analysis of P2 1-3.

endo monomer

ratio (mol%)

Mn (kDa) PDI dn/dc

P2-1 20 72 1.39 0.067

P2-2 20 83 1.30 0.065

P2-3 20 110 1.36 0.067

Glutaric acid (133.4 mg, 1.00 mmol), gDCC (171.0 mg, 1.00 mmol), and DPTS (118.9 mg,

0.40 mmol) were dried under high vacuum in 40 °C oil bath for 24 hours. Collect all three

Cl Cl

O O

O

)m

ClCl

OHHO HO OH

O O+ DIC, DPTS

DCMO

(

P3

S8

reagents in a 25 mL round bottom flask and nitrogen purge for 20 minutes. Then 3 mL

anhydrous DCM was added dropwise by syringe. Heat the solution to 40 °C to fully

dissolve reactants and subsequently cool the solution to room temperature. Next, DIC (0.74

mL, 4.8 mmol) was added dropwise to initiate the polymerization. The solution was kept

at room temperature for 2-3 days to yield polymers with different molecular weights.

Precipitate the polymer using MeOH and redissolve it with DCM alternately for 3 times.

A white polymer P3 (180 mg) was obtained. 1H NMR (500 MHz, CDCl3) δ 4.25 (s, 2H), 2.46 (t, J = 7.0Hz, 2H), 2.14 (s, 1H), 2.01 (t, J

= 7.0Hz, 1H).

Table S3. Mn, PDI, and dn/dc values of three characterized P3 1-3. The average dn/dc of

P3 (0.073) is used for the 𝛷i analysis of P3 1-3.

Mn (kDa) PDI dn/dc

P3-1 143 1.28 0.073

P3-2 160 1.22 0.070

P3-3 199 1.21 0.076

3. Thermal degradation of P1 and P2

60 mg of P1 (Mn = 160 kDa, exo adduct ratio: 21 %) was dissolved in 5 mL anhydrous

DMSO, and the solution was bubbled with nitrogen for 20 mins. The thermal degradation

proceeded at 130 °C for 1.5 h. Dilute the solution with 50 mL DCM. Wash the organic

O O

O

O

Cl Cl

O O)( )m n

ON

O(

OO

O

H

HDMSO130oC

Cl Cl

O O

O)O

O(

PO O

O N

O

O

O

AMPB

S9

phase with 50 mL DI water for 3 times and saturated brine once. Dry the organic phase

with anhydrous MgSO4 and evaporate solvent. 47 mg (yield: 72 %) of yellow viscous liquid

(Mn = 2.7 kDa, PDI = 1.98 from GPC analysis) was obtained. MALDI-TOF mass spectra

of degraded P1 was collected using 2-[3-(4-tert-butylphenyl)-2-methyl-2-

propenylidene]malononitrile (DCTB) (Sigma) as a matrix. The mass spectrometer was

calibrated using insulin (5729.6 kDa). The spectra is shown as Figure S1, and the main

peaks were confirmed to be peaks of [AMPB + Na]+.

54 mg of P2 (Mn = 110 kDa, endo adduct ratio: 20 %) was dissolved in 5 mL anhydrous

DMSO, and the solution was bubbled with nitrogen for 20 mins. The thermal degradation

proceeded at 130 °C for 1.5 h. Dilute the solution with 50 mL DCM. Wash the organic

phase with 50 mL DI water for 3 times and saturated brine once. Dry the organic phase

with anhydrous MgSO4 and evaporate solvent. 40 mg (yield: 74 %) of yellow viscous liquid

(Mn = 2.8 kDa, PDI = 2.29 from GPC analysis) was obtained. MALDI-TOF mass spectra

of degraded P2 was collected using 2-[3-(4-tert-butylphenyl)-2-methyl-2-

propenylidene]malononitrile (DCTB) (Sigma) as a matrix. The mass spectrometer was

calibrated using insulin (5729.6 kDa). The spectra is shown as Figure S2, and the major

peaks were confirmed to be peaks of [AMPB + Na]+.

S10

Figure S1. MALDI-TOF mass spectra of thermally degraded P1.

m/z Ion m/z Ion

1426.016 [AM4B + Na]+ 2762.646 [AM9B + Na]+

1693.870 [AM5B + Na]+ 3030.705 [AM10B + Na]+

1960.842 [AM6B + Na]+ 3298.112 [AM11B + Na]+

2228.056 [AM7B + Na]+ 3565.562 [AM12B + Na]+

2495.14 [AM8B + Na]+ …

S11

Figure S2. MALDI-TOF mass spectra of thermally degraded P2.

To calculate the theoretical molecular weight of fully degraded polymer, we referred to the

calculations of Lee.3 Relevant calculation results are shown in the table below:

m/z Ion m/z Ion

1426.929 [AM4B + Na]+ 2763.040 [AM9B + Na]+

1693.857 [AM5B + Na]+ 3030.140 [AM10B + Na]+

1960.945 [AM6B + Na]+ 3298.127 [AM11B + Na]+

2227.980 [AM7B + Na]+ 3565.627 [AM12B + Na]+

2495.192 [AM8B + Na]+ …

S12

DA monomer

ratio

Mn, f (kDa) Mn, r (kDa) Mn, b (kDa)

P1 21 % 2.7 2.0 122

P2 20 % 2.8 2.1 81.0

in which Mn, f represents the final Mn of thermally degraded polymers measured from GPC,

Mn,r represents the theoretical Mn of completely random copolymers P1 and P2 (complete

rDA reactions in polymers), and Mn, b represents the theoretical Mn of diblock copolymers

P1 and P2 (small molecular rDA framents have been removed).

4. Sonication Ultrasound experiments were performed in anhydrous THF on a Vibracell Model VCX500

operating at 20 kHz with a 13.1 mm replaceable titanium tip probe from Sonics and

Materials. 2.0 mg/mL of the polymer solution was prepared. The solution was transferred

to a 3-necked Suslick cell in an ice-water bath and bubble nitrogen for 15 minutes prior to

sonication. Sonication power was set at amplitude 20% (8.0 W/cm2) while maintaining the

temperature at 6-9 °C under nitrogen. The sonication pulse was set to 1s on / 1s off. While

performing sonication, aliquot of 0.8 mL of the solution was taken at each time point, of

which 0.3 mL was filtered for GPC analysis. The remaining solution was dried and the

polymer was dissolved in CDCl3 for NMR analysis. The Mn value was chosen to conduct

molecular weight analysis.

S13

4.1 2-hour sonication experiment

2-hour sonication experiments were performed at above experimental conditions. Aliquots

of 0.8 mL of the solution were taken at 30 min, 60 min, and 120 min time points.

Figure S3. 1H NMR of P1 of 2-hour sonication. The appearance of peaks of furan protons

indicates the mechanochemical retro-DA reactions in P1.

S14

Figure S4. 1H NMR of P2 of 2-hour sonication. The appearance of peaks of furan protons

indicates the mechanochemical retro-DA reactions in P2.

ClCl

OO

H H H H

sonicationO O

Ha Ha

Hb

Cl

ClHc

Hd Hd

HgDCC

S15

Figure S5. 1H NMR of P1 of 2-hour sonication. The appearance of peaks of Ha (4.77), Hb

(6.12), Hc (4.72), and Hd (4.37) at each time point indicates the ring opening reactions of

gDCC in polymer P1 degradation.

S16

Figure S6. 1H NMR of P2 of 2-hour sonication. The appearance of peaks of Ha (4.77), Hb

(6.12), Hc (4.72), and Hd (4.37) at each time point indicates the ring opening reactions of

gDCC in polymer P2 degradation.

4.2 Ring opening determination and Scission Cycle calculation.

The degree of gDCC ring opening reaction was determined by the equation below:

Ring Opening = 2∫Ha / (2∫Ha +∫HgDCC)

in which ∫Ha means the integration of Ha peak at chemical shift 4.77, and ∫HgDCC means

the integration of HgDCC peak at the chemical shift 4.25.

Meanwhile, the scission cycle is calculated by below equation:

Scission Cycle = [ln(Mn,0) - ln(Mn,t)]/ln2

in which Mn,0 represents the initial number-averaged molecular weight (before sonication),

Mn,t represents the number-averaged molecular weight at each time point (at t min).

S17

4.3 Sonication experiments to determine 𝜱i

2.0 mg mL-1 of P1, P2 and P3 polymer solutions (around 17 mL) were prepared. Aliquots

of 0.8 mL of the solution were taken at 2 min, 4 min, 6 min, 8 min, 12 min, 20 min and 30

min time points, of which 0.3 mL was filtered for GPC analysis. The remaining solution

was dried in a small vial and then wash the vial with MeOH three times. After dried under

vacuum, dissolve the polymer in CDCl3 for NMR analysis. The Mn value was chosen to

conduct molecular weight analysis.

The analysis of P1 1-3, P2 1-3 and P3 1-3 sonication were listed below:

P1-1

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 77.4

4min 66.3 0.2248 1 39.86 0.0478

6min 62.6 0.3063 1 31.21 0.0602

8min 59.2 0.3871 1 26.05 0.0713

12min 56.2 0.4619 1 21.41 0.0854

20min 51.6 0.5859 1 14.97 0.1179

P1-2

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 155

4min 116 0.4165 1 32.78 0.0575

6min 106 0.5449 1 25.17 0.0736

8min 98.5 0.6562 1 20.91 0.0873

12min 87.2 0.8271 1 16.91 0.1058

20min 72.8 1.0924 1 10.9 0.1550

S18

P1-3

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 220

2min 168 0.3900 1 43.69 0.0438

4min 137 0.6783 1 33.88 0.0557

6min 126 0.7997 1 26.04 0.0713

8min 109 1.0095 1 20.43 0.0892

12min 96.9 1.1834 1 18.69 0.0967

20min 81.1 1.4403 1 13.8 0.1266

Figure S7. 𝛷i (the slope of the fitting curve of the ring opening as a function of scission

cycle) of P1 1-3.

0.0 0.5 1.0 1.5 2.00.00

0.05

0.10

0.15

0.20

Scission Cycle

Ring

ope

ning

(Φ)

P1-1 77 kDa

P1-3 220 kDa

P1-2 160 kDa

y=0.194x R2=0.977

y=0.136x R2=0.984

y=0.0862x R2=0.963

S19

P2-1

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 72.4

2min 63.6 0.1870 1 98.22 0.0200

4min 59.6 0.2807 1 63.87 0.0303

8min 53.5 0.4365 1 49.94 0.0385

12min 49.6 0.5456 1 39.16 0.0486

20min 44.7 0.6957 1 33.53 0.0563

P2-2

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 82.5

4min 67.6 0.2895 1 68.92 0.0282

6min 63.7 0.3731 1 56.29 0.0343

8min 58.5 0.4960 1 45.31 0.0423

12min 55.2 0.5823 1 39.74 0.0479

20min 49.4 0.7399 1 31.34 0.0600

P2-3

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 105.4

4min 82.9 0.3464 1 66.07 0.0294

6min 78.6 0.4232 1 56.87 0.0340

8min 72.6 0.5378 1 49.7 0.0387

12min 65.5 0.6863 1 40.01 0.0476

20min 56.6 0.8970 1 29.77 0.0630

S20


cycle) of P2 1-3.

P3-1

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 143

2min 119 0.2631 1 10.16 0.1645

4min 113 0.3389 1 7.53 0.2099

6min 109 0.3882 1 5.74 0.2584

8min 105 0.4530 1 4.79 0.2946

12min 95.3 0.5860 1 3.43 0.3683

0.0 0.5 1.0 1.50.00

0.02

0.04

0.06

0.08

Scission Cycle

Ring

ope

ning

(Φ)

P2-1 72 kDa

P2-3 110 kDa

P2-2 83 kDa

y=0.0872x R2=0.917

y=0.0843x R2=0.951

y=0.0722x R2=0.946

S21

P3-2

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 160

2min 132 0.2742 1 10.95 0.1544

4min 123 0.3840 1 7.09 0.2200

6min 114 0.4889 1 5.7 0.2597

8min 107 0.5843 1 4.65 0.3008

12min 99.0 0.6938 1 3.57 0.3591

20min 83.0 0.9482 1 2.46 0.4484

P3-3

Mn (kDa) Scission

Cycle

∫Ha ∫HgDCC Ring

Opening

0min 199

2min 165 0.2707 1 11.15 0.1521

4min 144 0.4689 1 6.82 0.2268

6min 131 0.6010 1 4.99 0.2861

8min 120 0.7331 1 4.27 0.3190

12min 105 0.9301 1 2.85 0.4124

20min 86.6 1.203 1 2.03 0.4963

S22


cycle) of P3 1-3.

Table S4. List of 𝛷i of P1 1-3, P2 1-3 and P3 1-3.

P1 P2 P3

-1 0.19 0.087 0.63

-2 0.14 0.084 0.51

-3 0.086 0.072 0.44

0.0 0.5 1.0 1.50.0

0.2

0.4

0.6

Scission Cycle

Ring

ope

ning

(Φ)

P3-1 140 kDa

P3-2 160 kDa

P3-3 200 kDay=0.634x R2=0.945

y=0.506x R2=0.961

y=0.435x R2=0.958

S23

4.4 Mn,4h measurements

2.0 mg/mL of P1 (Mn,0 = 53 kDa, PDI = 1.4, DA monomer ratio = 20 mol%) and P2 (Mn,0

= 58 kDa, PDI = 1.3, DA monomer ratio = 20 mol%) polymer solutions (~17 mL) were

prepared. Aliquots of 0.5 mL of the solution were taken at 20 min, 40 min, 60 min, 120

min, 180 min, and 240 min, then filtered for GPC analysis. The sample at 240 min was

analyzed by three runs and the average was calculated as Mn,4h.

Table S5. Mn of P1 and P2 at different sonication time t.

t (min) 0 20 40 60 120 180 240-1 240-2 240-3

P1 53.4 45.3 40.3 37.9 32.9 30.1 29.5 29.6 29.4

P2 57.9 45.1 40.7 37.4 29.1 28.1 26.6 26.6 26.4

Table S6. PDI of P1 and P2 at different sonication time t.

t (min) 0 20 40 60 120 180 240

P1 1.43 1.32 1.26 1.23 1.22 1.21 1.19

P2 1.34 1.26 1.25 1.24 1.22 1.18 1.16

S24

Figure S10. The normalized RI traces of P1 at different sonication time.

Figure S11. The normalized RI traces of P2 at different sonication time.

S25

Figure S12. The PDI of P1 and P2 at different sonication time t.

5. Calculation of transition state geometry

The geometries of the stationary points of endo and exo DA adducts were optimized using

density functional B3LYP with the 6-31G(d) basis set. Synchronous Transit-guided Quasi-

Newton (STQN) method4 in Gaussian 095 was applied to locate the transition state

geometries and results were confirmed with frequency analysis (only one imaginary

frequency). The intrinsic reaction coordinate (IRC) was followed from the transition state

to both reactants and products.

The geometry and coordinates for the ground state of exo DA adduct

----------------------------------------------------------------------

# opt freq=noraman b3lyp/6-31g(d) scrf=(solvent=thf) geom=connectivity

----------------------------------------------------------------------

S26

Zero-point correction= 0.314937 (Hartree/Particle)

Thermal correction to Energy= 0.336612

Thermal correction to Enthalpy= 0.337557

Thermal correction to Gibbs Free Energy= 0.258763

Sum of electronic and zero-point Energies= -1162.846545

Sum of electronic and thermal Energies= -1162.824870

Sum of electronic and thermal Enthalpies= -1162.823926

Sum of electronic and thermal Free Energies= -1162.902719

C -3.12344 0.99969 0.27624

C -1.61547 1.08237 -0.00169

C -2.15107 2.93339 1.08219

C -3.44864 2.13182 0.94071

H -2.03158 3.62886 1.93116

C -0.80527 -0.1776 -0.16719

H 0.12955 -0.11547 0.45265

H -0.54174 -0.32877 -1.24945

O -1.61685 -1.27165 0.27412

C -1.00572 -2.49899 0.38673

O -1.8053 -3.36135 0.7662

C 0.43416 -2.67672 0.07235

H 0.66127 -2.28768 -0.95122

H 1.05777 -2.12399 0.81922

H 0.69777 -3.76244 0.116

O -1.1672 1.85041 1.17471

H -3.7246 0.14976 -0.03667

H -4.40593 2.48398 1.31589

C -1.47682 2.16492 -1.12045

H -2.13469 1.94623 -1.99315

C -1.86037 3.4758 -0.34775

S27

H -2.73423 4.01478 -0.78088

N 0.3911 3.66655 -1.14476

C -0.61194 4.34276 -0.41304

C -0.04278 2.39543 -1.57866

O 0.6538 1.61377 -2.23706

O -0.46527 5.46799 0.07639

C 1.71475 4.17886 -1.35615

H 2.42804 3.31012 -1.44789

H 2.00919 4.79854 -0.46111

C 1.84007 5.05252 -2.61826

H 1.21942 5.98168 -2.53406

H 1.56247 4.48455 -3.54364

O 3.22892 5.39809 -2.67313

C 3.62333 6.26041 -3.66837

C 2.64615 6.81116 -4.64062

H 2.11202 5.98027 -5.16495

H 1.89522 7.44723 -4.10862

H 3.17929 7.43674 -5.39833

O 4.83817 6.48017 -3.61475

The geometry and coordinates for the transition state of exo DA adduct

----------------------------------------------------------------------

# opt=(calcfc,qst3) freq=noraman b3lyp/6-31g(d) scrf=(solvent=thf) geom=connectivity

----------------------------------------------------------------------



S28







C 3.13352 1.72561 0.88006

C 2.21718 0.61308 0.36925

C 1.55544 2.41604 -0.60686

C 2.7266 2.83947 0.26771

H 1.32003 3.00695 -1.49056

C 2.73996 -0.8062 0.38254

H 2.0866 -1.45142 -0.20927

H 2.7612 -1.17876 1.41196

O 4.06618 -0.78022 -0.17054

C 4.78682 -1.92222 -0.33306

O 5.90861 -1.82444 -0.77993

C 4.14231 -3.2354 0.04775

H 3.8413 -3.24152 1.10074

H 3.24462 -3.42102 -0.552

H 4.86181 -4.03536 -0.12629

O 1.90938 1.06673 -0.96338

H 3.88715 1.60082 1.64754

H 3.06073 3.85921 0.41475

C 0.81788 0.85507 1.07669

H 0.90962 0.91528 2.16271

C 0.35015 2.14863 0.36578

H 0.13921 2.9974 1.01923

N -1.16564 0.40114 -0.13457

S29

C -0.90964 1.74991 -0.3877

C -0.22645 -0.18989 0.70624

O -0.2567 -1.35588 1.05619

O -1.59454 2.45187 -1.10559

C -2.27158 -0.3299 -0.73869

H -1.96966 -1.37432 -0.83764

H -2.45473 0.09059 -1.7296

C -3.53641 -0.22844 0.1145

H -3.84588 0.81705 0.21007

H -3.35761 -0.64556 1.11104

O -4.53314 -0.99403 -0.58077

C -5.8119 -1.08582 -0.12658

C -6.1772 -0.33612 1.1338

H -5.55424 -0.64926 1.97822

H -6.03919 0.74265 1.00285

H -7.22339 -0.5379 1.36334

O -6.59081 -1.76225 -0.76142

The geometry and coordinates for the ground state of endo DA adduct

----------------------------------------------------------------------

# opt freq=noraman b3lyp/6-31g(d) scrf=(solvent=thf) geom=connectivity

----------------------------------------------------------------------






S30




C -1.62228 1.19855 0.00

C -2.50555 1.84426 1.07288

C -1.69063 3.50254 -0.14126

C -1.12391 2.21442 -0.74181

C -1.55486 2.55274 2.08939

H -2.11892 2.90758 2.98452

C -0.97579 3.72681 1.22399

H -1.2174 4.73309 1.64148

H -1.82671 4.38404 -0.79245

O -2.99458 3.02787 0.34

N 0.82871 2.35755 2.00029

C 0.52788 3.50302 1.22524

O 1.38536 4.20623 0.68014

C -0.33699 1.74688 2.51447

O -0.33156 0.73415 3.22339

C -3.63251 1.06339 1.69515

H -4.44511 1.75996 2.03384

H -3.24058 0.46376 2.5606

O -4.13775 0.17107 0.69492

C -5.25553 -0.56365 1.01782

O -5.58262 -1.30828 0.08779

C -5.92142 -0.41486 2.33598

H -5.18855 -0.58364 3.16349

H -6.34988 0.61433 2.432

H -6.74987 -1.16032 2.42602

C 2.15995 1.88568 2.25317

S31

H 2.19338 1.43775 3.28752

H 2.86612 2.76424 2.21424

C 2.63958 0.8248 1.24501

H 2.6133 1.21224 0.19381

H 2.03702 -0.11668 1.32519

O 3.99503 0.56128 1.62498

C 4.68952 -0.35957 0.87698

O 5.8426 -0.50024 1.29875

C 4.05639 -1.0498 -0.2746

H 3.15705 -1.62089 0.06614

H 3.74156 -0.30201 -1.0446

H 4.78538 -1.76084 -0.73581

H -0.45245 2.20274 -1.59704

H -1.4927 0.12218 -0.080

The geometry and coordinates for the transition state of endo DA adduct

----------------------------------------------------------------------

# opt=(calcfc,qst3) freq=noraman b3lyp/6-31g(d) scrf=(solvent=thf) geom=connectivity

----------------------------------------------------------------------









S32

C 5.17316 0.54429 1.81189

C 3.99951 0.2754 1.17168

C 4.3694 2.43416 0.93359

C 5.41332 1.94948 1.65982

C 0.5227 1.29434 -1.20146

H 1.557 1.39467 -0.898

C -0.16083 1.95946 -2.13851

H 0.17498 2.74423 -2.80362

H 4.10561 3.41456 0.56707

O 3.49465 1.43179 0.62876

N -1.63758 0.44793 -1.17973

C -1.56969 1.44501 -2.16413

O -2.49191 1.7903 -2.87539

C -0.39929 0.30303 -0.55568

O -0.15456 -0.48972 0.33863

C 3.21449 -0.96411 0.96196

H 2.15191 -0.79312 1.15565

C 2.75357 -2.48243 -0.90771

O 2.91964 -2.75992 -2.07723

C 1.88757 -3.29178 0.03057

H 2.44179 -3.61001 0.91963

H 1.03095 -2.69655 0.36443

H 1.53008 -4.17153 -0.50503

C -2.81709 -0.34702 -0.88305

H -2.49536 -1.35726 -0.6194

H -3.42733 -0.39505 -1.78753

C -3.6278 0.25686 0.2648

H -3.96923 1.26339 0.00149

H -3.01798 0.30861 1.17238

S33

O -4.74747 -0.62266 0.45523

C -5.67051 -0.40487 1.42968

O -6.58859 -1.18934 1.52596

C -5.4892 0.79738 2.32775

H -4.54258 0.74075 2.87595

H -5.48045 1.72712 1.74896

H -6.31484 0.82388 3.03875

H 6.25043 2.51722 2.04116

H 5.79329 -0.17391 2.33063

Table S7. Gibbs free energy (298.15 K, 1 atm) of the ground and transition states of exo

and endo isomers, and activation energies calculated at B3LYP/6-31G(d) level.

GGS (hartree) GTS (hartree) ∆𝑮‡ (kcal/mol)

exo -1162.902719 -1162.863244 24.77

endo -1162.897429 -1162.861385 22.62

6. Modeling of the activation lengths The force-free activation length (∆𝑥‡) correlates with the changes from their ground states

to transition states along the extension of polymer backbone. First, geometries of ground

and transition states were obtained as described in section 5. Then 2,3-dichloroalkene-

bearing short attachments were added to include polymer backbone effect (2,3-

dichloroalkene is the product form of gDCC ring-opening reactions). For CoGEF

calculations, “freezing atom” function in Spartan software was applied to freeze transition

states geometries to avoid them relaxing back to ground states. The molecule

representations and CoGEF results are shown below. The force values were calculated as

described in Figure 5 in the main text and force values ranging from 200 pN to 900 pN are

S34

selected for the linear fit.

Figure S13. CoGEF of (a) ground state of exo isomer, (b) transition state of exo isomer,

(c) ground state of endo isomer and (d) transition state of endo isomer.

S35

7. 1H and 13C NMR

O

HO

NOH

H

O

OH

S36

S37

O

HON

OH

HH

O

O

S38

S39

ClCl

OHHO

S40

S41

O

O

O

N

H

O

O

H O

Cl Cl

O O

O

O

O( )( )m n121

3

6 8

75

49

1011HgDCC

910

HgDCC

1 23

6 68

4 5

10

911

MeOH

HgDCC + 7

S42

O

O

N

H

H

O

O

O

Cl Cl

O O

)( )m n

O

OO

O(

121

3

4

5

67

8 HgDCC HgDCC9 910 1011

S43

Cl Cl

O O

O

)m

O

(

S44

8. References 1. Moore, J. S.; Stupp, S. I., Room temperature polyesterification. Macromolecules 1990,

23 (1), 65-70.

2. Pustovit, Y. M.; Ogojko, P. I.; Nazaretian, V. P.; Rozhenko, A. B., Reactions of

cycloalkanecarboxylic acids with SF4. II. Fluorination of gem-

dichlorocyclopropanecarboxylic acids with SF4. J. Fluorine Chem. 1994, 69 (3), 231-6.

3. Lee, B.; Niu, Z.; Wang, J.; Slebodnick, C.; Craig, S. L., Relative Mechanical

Strengths of Weak Bonds in Sonochemical Polymer Mechanochemistry. J. Am. Chem. Soc.

2015, 137 (33), 10826-32.

4. Peng, C.; Ayala, P. Y.; Schlegel, H. B.; Frisch, M. J., Using redundant internal

coordinates to optimize equilibrium geometries and transition states. J. Comput. Chem.

1996, 17 (1), 49-56.

5. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A. C., J. R.;

Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.;

Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada,

M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda,

Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.;

Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.;

Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.;

Cossi, M.; Rega, N.; Millam, M. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.;

Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;

Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V.

G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.;

Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. 2010.

Documents

Supporting Information forZi Wang and Stephen L. Craig* Department of Chemistry, Duke University, Durham, North Carolina 27708 *To whom correspondence should be addressed. Phone: (919)