Supporting information
Methods
Butane-1,4-diyl bis(2-(((dodecylthio)carbonothioyl)thio)-2-methylpropanoate) (CTA 1). S-1-Dodecyl-S’-(α,α’dimethyl-α”-acetic acid)trithiocarbonate (DAA-TTC) was prepared using methods reported in literature. Thionyl chloride
(4.893 g, 0.041 mol) was added to DAA-TTC (1.011 g, 3.004 mmol) and the mixture was stirred and heated to reflux at 70
C for 3 hours. Excess thionyl choride was removed through high vacuum distillation to obtain a dark yellow liquid, which
was used without purification. 1,4-butanediol (0.101 g, 1.113 mmol) was weighed into a round bottom flask. Into the same
flask, triethylamine (0.225 g, 2.22 mmol) and dichloromethane (10 mL) were added. The dark yellow liquid was diluted with
dichloromethane (10 mL) before added drop-wise into the reaction flask while keeping the temperature at 0 C. The reaction
was then left to stir at room temperature overnight. Any white precipitate formed was removed via gravity filtration. The
reaction solution was diluted with more dichloromethane (50 mL) before washing with water (2 x 100 mL). The organic
layers collected were dried with magnesium sulphate and dichloromethane was then evaporated off. 7 was yielded as a dark
yellow oil (50 %) after purification through a silica column using n-hexane: ethyl acetate 90: 10 as an eluent. 1H NMR
(CDCl3):  = 0.88 (t, -CH2-CH3, 6H), 1.25-1.4 and 1.62-1.69 (m, -(CH2)10CH3, 40H), 1.68 (s, -C(CH3)2, 12H), 3.26 (t, SCH2, 4H), 4.09 (m, O-CH2, 4H). 13C NMR (CDCl3):  = 14.09 ((CH2)10CH3), 22.66 ((CH2)10CH3), 25.06 ((CH2)10CH3),
25.36 (S-C(CH3)2), 27.86 ((CH2)10CH3), 28.94 ((CH2)10CH3), 29.09 ((CH2)10CH3), 29.32 ((CH2)10CH3), 29.44((CH2)10CH3),
29.54((CH2)10CH3), 29.61((CH2)10CH3), 31.89 ((CH2)10CH3), 36.91((CH2)10CH3), 55.94 (S-C(CH3)2), 65.38 (O-CH2),
172.89 (C=O), 221.45 (C=S).
2,2-bis((acryloyloxy)methyl)propane-1,3-diyl diacrylate. Acrylic acid was converted to acryloyl chloride before used for
esterification with pentaerythritol via the general procedure described in paper. 1H NMR (CDCl3):  = 4.30 (s, 0-CH2, 8H),
5.88 (dt, CH=CH, 4H), 6.11 (q, C=CH-C=O, 4H), 6.42 (dd, CH=C-C=O, 4H).
2,2-bis((methacryloyloxy)methyl)propane-1,3-diyl bis(2-methylacrylate). Methacryloyl chloride was used as received for
esterification with pentaerythritol using procedure (2) described in paper. Eluent used for column chromatography was nhexane: ethyl acetate 90: 10. Product was further purified by recrystallisation in ethanol at -4 °C to yield white crystals (24
%). 1H NMR (CDCl3):  = 1.94 (t, -C(CH)3, 12H), 4.29 (s, O-CH2, 8H), 5.60 (m, C(CH3)=CH, 4H), 6.09 (m, C=CH, 4H).
2,2-bis(((bicyclo[2.2.1]hept-5-ene-2-carbonyl)oxy)methyl)propane-1,3-diyl
bis(bicyclo[2.2.1]hept-5-ene-2carboxylate). 5-norbornene-2-carboxylic acid (mixture of endo and exo, predominantely endo) was reacted with thionyl
chloride, followed by esterification with pentaerythritol using the procedure as described in paper. Eluent used for column
chromatography was n-hexane: ethyl acetate 90: 10. Product was further purified by recrystallisation in ethanol at -4 °C to
yield white crystals (30 %). 1H NMR (CDCl3):  = 1.26-1.49, 1.86-1.95, 2.22 (q), 2.93-3.00, 3.12 (s), 4.02-4.15, 5.87 (q),
6.09-6.21. 13C NMR (CDCl3):  = 29.12, 30.38, 41.62, 42.03, 42.49, 43.04, 43.28, 45.82, 46.36, 46.60, 49.70, 62.07, 62.15,
62.38, 132.13, 135.59, 138.06, 138.12, 174.20, 175.74 (1D and 2D spectra included in appendices).
Results and Discussion
Fig. 1. GPC chromatograms of PNIPAAm at different RAFT polymerisation times using CTA1.
Normalised RI Response
As shown in Fig. 2, the chain extension of P(NIPAAm) chains with styrene shows a shift in the GPC trace of the
P(NIPAAm), which acted as a macroCTA, to higher molecular weight. The trithiocarbonate RAFT groups of the
P(NIPAAm-b-styrene) copolymer were reduced through aminolysis and a shift to lower molecular weight was observed
from the GPC traces (Fig. 3).
1.0
0.8
0.6
0.4
0.2
0.0
12
14
16
18
20
Time (min)
Normalised RI Response
Fig. 2 GPC traces before (solid line) and after chain extension of P(NIPAAm) macroRAFT CTA with styrene (dashed line).
1.0
0.8
0.6
0.4
0.2
0.0
13
14
15
16
17
18
19
Time (min)
Fig. 3 GPC traces from before (solid line) and after aminolysis of P(NIPAAm-b-styrene) (dashed line).
The NMR spectrum shown in Fig. 4 (B) is of the reaction mixture of 1-dodecanethiol, which is a simple primary thiol with
alkyl chain, with the four-arm norbornene crosslinker via the photoinitiated thiol-ene reaction. The vinyl peaks of the
norbornene (Fig. 4 (A)) at 5.9-6.2 ppm (region in box) disappeared after the reaction and peaks of norbornane appeared at
1.2-1.8 ppm and 2.2-2.8 ppm, which overlapped with the alkyl peaks of 1-dodecanethiol. The aromatic ring peaks from the
photoinitiator were also visible in the spectrum at approximately 7.3-8.0 ppm. Fig. 5 and Fig. 6 show reactions performed
under similar conditions except that the four-arm acrylate and the four-arm methacrylate crosslinkers were used.
Fig. 4 1H NMR spectra of (A) Norbornene crosslinker and (B) Stoichiometric reaction of the norbornene crosslinker and 1dodecanethiol in dichloromethane. The region in the box shows the disappearance of the vinyl groups of the norbornenes after photoinitiated
thiol-ene reaction.
Fig. 5 1H NMR spectra of (A) Acrylate crosslinker and (B) Stoichiometric reaction of the acrylate crosslinker and 1dodecanethiol in dichloromethane. The region in the box shows the disappearance of the vinyl groups of the acrylate after photoinitiated
thiol-ene reaction.
Fig. 6 1H NMR spectra of (A) Methacrylate crosslinker and (B) Stoichiometric reaction of the methacrylate crosslinker and 1dodecanethiol in dichloromethane. The region in the box shows the disappearance of the vinyl groups of the methacrylate after
photoinitiated thiol-ene reaction.