Electronic Supporting Information
Dendritic hydrogels: From exploring various crosslinking chemistries to
introducing functions and naturally abundant resources
Surinthra Mongkhontreerat, Oliver C. J. Andrén, Assya Boujemaoui and Michael Malkoch
KTH Royal Institute of Technology, Department of Fibre and Polymer Technology, Teknikringen 5658, SE-100 44 Stockholm, Sweden
Materials
PEG 8 kDa, PEG 6 kDa, 4-(Dimethylamino)pyridine (DMAP), pyridine, DOWEX, p-toluenesulfonic acid (pTSA), succinic
anhydride, sodium carbonate (Na2(CO3)), 1,1'-carbonyldiimidazole (CDI), NHS, trifluoroacetic acid, copper sulfate
(Cu(II)SO4), sodium ascobate (NaASC), BSA and ethylenediamine tetra acetic acid (EDTA) were purchased from SigmaAldrich. Diethyl ether, dichloromethane (DCM), methanol (MeOH), toluene, 99% ethanol (EtOH) and tetrahydrofuran (THF)
were purchased from Merck. Bis-MPA was donated from Perstorp AB, Sweden. All the purchased chemicals were used as
received. Several precursor materials have been synthesized following previous publications including: acetonide protected
bis-MPA anhydride18, allyloxy anhydride16, pent-ynoic anhydride19, 6-azidohexanoic anhydride20, lithium phenyl-2,4,6trimethylbenzoylphosphinate (LAP)21, 22, di-functional thiol PEG 6 kDa5, azide functionalized rhodamin B19 and thiol
functionalized cellulose nanocrystal23.
Methods
Nuclear Magnetic Resonance (NMR) spectroscopy was performed with a Bruker AM NMR. 1H-NMR and 13C-NMR
spectroscopies were operated at 400 MHz and 100 MHz respectively using CDCl3 or DMSO-d6 as solvent.
Size Exclusion Chromatography (SEC) measurements were conducted on a TOSOH EcoSEC HLC-8320GPC system
equipped with an EcoSEC RI detector and three columns (PSS PFG 5µm; Microguard, 100Å, and 300Å) (MW resolving range:
300-100 000 Da) from PSS GmbH, using DMF with 0.01M LiBr as the mobile phase at a flow of 0.2 mL min -1 and at 50 °C. A
narrow linear PEG standard was used as a conventional calibrant with toluene as an internal standard for correction of flow
rate fluctuation. The data were processed with the software PSS WinGPC Unity version 7.2.
Differential Scanning Calorimetry (DSC) experiments were conducted on a Mettler Toledo DSC. The heating and cooling
rate were fixed at 10 °C/min under nitrogen flow. The temperature was increased from 25 °C to 120 °C, stabilized for 2 min,
decreased to -80 °C, stabilized 2 min and increased again to 120 °C. The melting temperature (T m) and enthalpy of melting
(∆Hm) were obtained from the second heating.
Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI) was performed with Bruker
Ultraflex MALDI-TOF MS with SCOUT-MPT ion source (Bruker Daltonics) with N2 (337 nm) calibrated with SpericalTM
calibrants. The matrix used were trans-2-[3-(4-tert-Butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB) and 2-(4Hydroxyphenylazo)benzoic acid (HABA). The spectra were analyzed utilizing FlexAnalysis and PolyTools software.
UV induced crosslinking was operated under 100W Hg table-top UV lamp (Blak Ray B 100AP) 365 nm band pass filter
with the intensity of 9 mW.m-2.
General notes and Definition
Throughout the article, the DLD block copolymer based on PEG and bis-MPA dendrons will be named DLD-xk-Gy-Z and
linear PEG will be named L-xk-Z. The letter x is referred to molecular weight of the PEG in kDa, y is referred to the dendritic
generation and Z is the functional groups of the polymer.
The crosslink networks will be named after the crosslinking chemistries as TE refers to crosslink networks from thiol-ene, TY
for thiol-yne, CC for CuAAC and AN for amine-NHS coupling.
Dendritic-linear-dendritic block copolymers synthesis
Synthesis of DLD-8k-G1-Ac (3) – General growth/anhydride coupling procedure
PEG-8k-OH (1) (100.0 g, 12.5 mmol), DMAP (0.6 g, 5 mmol) and pyridine (5.58 ml, 75 mmol) were dissolved in
dichloromethane (DCM) (250 ml). The solution was placed on an ice bath and acetonide protected bis-MPA anhydride (2)
(12.4 g, 37.5 mmol) was slowly added to the system. The solution was left to react at room temperature overnight and
monitored with 13C-NMR and MALDI. DCM was further evaporated to a viscous solution and then precipitated in ether
twice. The product was collected as a white powder. Yield: 96 g, 92.4 %. 1H NMR (400 MHz, CDCl3) δ (ppm): 1.19 (6H, s, CH3), 1.36 (6H, s, CH3 acetonide group), 1.40 (6H, s, CH3 acetonide group), 3.62 (m, CH2 in PEG backbone), 3.67-3.70 (4H, m,
-CH2-O-dendron), 4.15 and 4.18 (4H, d, -CH2-O-dendron) and 4.26-4.28 (4H, t, -CH2-O-C(=O)-). 13C NMR (100 MHz, CHCl3) δ
(ppm): 18.49, 22.84, 24.08, 41.48, 63.1, 65.63, 68.73, 70.34, 97.65 and 173.69.
DLD-8k-G1-OH (4) – General activation procedure
DLD-8k-G1-Ac (3) (96.0 g, 11.5 mmol) and DOWEX (100.0 g) were mixed together in MeOH (200.0 ml). The reaction was let
stirred at room temperature for 1 hour and filtered of DOWEX. The reaction was rotorevaporated to eliminate the
generated acetone and redissolved again in MeOH (200.0 ml) together with DOWEX (50.0 g). After 1 hour, DOWEX was
filtered and the product was precipitated in ether, redissolve in 200.0 ml of water and freeze dried overnight. The reaction
was monitored with 1H-NMR and MALDI for the completion. The product was collected as a white powder. Yield: 94 g, 99%.
1H NMR (400 MHz, CDCl ) δ (ppm): 1.10 (6H, s, -CH ), 3.63 (m, CH in PEG backbone), 3.70-3.73 (8H, m, -CH -O-dendron)
3
3
2
2
and 4.32-4.34 (4H, t, -CH2-O-C(=O)-). 13C NMR (100 MHz, CHCl3) δ (ppm): 16.88, 49.56, 62.92, 65.45, 68.53, 70.24 and
174.84.
Synthesis of DLD-8k-G2-Ac (5)
DLD-8k-G1-OH (4) (94.0 g, 11 mmol), DMAP (1.2 g, 9.7 mmol) and pyridine (10.9 ml, 146 mmol) were dissolved in DCM (250
ml). The solution was placed on an ice bath and acetonide protected bis-MPA anhydride (2) (32.0 g, 97 mmol) was slowly
added to the system. Following the general growth procedure, the product was collected as a white powder. Yield: 96 g,
95%. 1H NMR (400 MHz, CDCl3) δ (ppm): 1.14 (12H, s, CH3 generation 2), 1.28 (6H, s, CH3 generation 1), 1.34 (12H, s, CH3
acetonide group), 1.40 (12H, s, CH3 acetonide group), 3.63 (m, CH2 in PEG backbone), 4.12 and 4.15 (12H, d, -CH2-Odendron) and 4.25-4.32 (8H, t, -CH2-O-C(=O)-). 13C NMR (100 MHz, CHCl3) δ (ppm): 17.02, 17.78, 21.39, 24.48, 41.23, 45.96,
63.51, 64.35, 65.14, 68.04, 69.81, 97.19, 171.67 and 172.60.
Activation of DLD-8k-G2-OH (6)
DLD-8k-G2-Ac (5) (96.0 g, 11 mmol) and DOWEX (100.0 g) were mixed together in MeOH (200.0 ml). Following the general
activation procedure the product was collected as a white powder. Yield: 93 g, 98 %. 1H NMR (400 MHz, CDCl3) δ (ppm):
1.05 (12H, s, -CH3 generation 2), 1.29(6H, s, -CH3 generation 1), 3.62 (m, CH2 in PEG backbone), 4.27-4.29 (8H, t, -CH2-OC(=O)-) and 4.12, 4.15 (4H, d, -CH2-O-dendron) . 13C NMR (100 MHz, CHCl3) δ (ppm): 16.42, 17.27, 45.70, 49.27, 63.55,
64.06, 65.18, 68.09, 69.81, 172.18 and 173.93.
Synthesis of DLD-8k-G3-Ac (7)
DLD-8k-G2-OH (6) (99.0 g, 10 mmol), DMAP (2.1 g, 17 mmol) and pyridine (19.0 ml, 0.26 mol) were dissolved in DCM (250
ml). The solution was placed on an ice bath and acetonide protected bis-MPA anhydride (2) (56.0 g, 0.17 mol) was slowly
added to the system. Following the general growth procedure, the product was collected as a white powder. Yield: 101.0 g,
90%. 1H NMR (400 MHz, CDCl3) δ (ppm): 1.14 (24H, s, CH3 generation 3), 1.26 (18H, s, CH3 generation 1 and 2), 1.34 (24H, s,
CH3 acetonide group), 1.40 (24H, s, CH3 acetonide group), 3.64 (m, CH2 in PEG backbone) and 4.12-4.31 (64H, m, -CH2-Odendron and -CH2-O-C(=O)-). 13C NMR (100 MHz, CHCl3) δ (ppm): 16.62, 17.45, 20.96, 24.38, 40.95, 45.83, 63.77, 64.82,
67.70, 69.55, 96.90, 170.77, 171.03 and 172.29.
Activation of DLD-8k-G3-OH (8)
DLD-8k-G3-Ac (7) (101.0 g, mmol) and DOWEX (100.0 g) were mixed together in MeOH (100.0 ml). Following the general
activation procedure the product was collected as a white powder. Yield: 95 g, 97 %. 1H NMR (400 MHz, CDCl3) δ (ppm):
1.06 (24H, s, -CH3 generation 3), 1.29 (18H, s, -CH3 generation 1 and 2), 3.63 (m, CH2 in PEG backbone), 4.26-4.38 (40H, m, CH2-O-C(=O)- and -CH2-O-dendron). 13C NMR (100 MHz, CHCl3) δ (ppm): 16.79, 17.36, 17.69, 46.32, 49.85, 64.40, 65.29,
68.48, 70.30, 172.07 and 74.42.
Functionalization of DLD-8k-G3-OH (8)
Functionalization of DLD-8k-G3-OH (8) is displayed in Scheme S1
Scheme S1: Synthesis route of DLD-8k-G3-Allyl (17), DLD-8k-G3-Alk (18) and DLD-8k-G3-NHS (15)
Synthesis of DLD-8k-G3-COOH (11)
DLD-8k-G3-OH (8) (20.0 g, 2 mmol), DMAP (0.8 mg, 6.6 mmol) and pyridine (7.4 ml, 0.1 mol) were dissolved in a mixture of
DCM (50.0 ml) and THF (50.0 ml). The solution was placed on an ice bath and succinic anhydride (10) (6.0 g, 60 mmol) was
slowly added to the system. The solution was left to react at room temperature overnight. The reaction was monitored with
13C-NMR and MALDI for the completion. DCM (400.0 ml) was added and reaction was extracted 3 times with 10% Na CO .
2
3
The product was purified by precipitation in ether and was collected as a white powder. Yield: 19.7 g, 84.3%. 1H NMR (400
MHz, CDCl3) δ (ppm): 1.22-1.28 (42H, m, CH3), 2.62 (64H, s, -C(=O)-CH2-CH2-C(=O)-), 3.63 (m, CH2 in PEG backbone), 4.214.32 (56H, m, -CH2-O-dendron generation 1,2 and 3). 13C NMR (100 MHz, CHCl3) δ (ppm): 16.70, 16.79, 17.00, 27.76, 28.11,
45.70, 45.97, 64.64, 68.02, 69.82, 170.92, 171.05, 171.16, 171.28 and 171.49.
Synthesis of DLD-8k-G3-NHS (15)
DLD-8k-G3-COOH (11) (6.0 g, 0.53 mmol) was dissolved in DCM and flushed with Ar for 10 minutes. CDI (12) (2.1 g, 13
mmol) was slowly added to the reaction vessel with the outlet for CO 2 by product. The reaction was reacted for 2 hours and
monitored via 1H-NMR and MALDI to confirm the fully substitution. Then after, NHS (14) (1.5 g, 0.013 mol) was added and
the reaction was allowed to react for 2 hours. The reaction was confirmed by 1H-NMR. The solution was extracted with
water and precipitated in ether. Yield: 5.1 g, 75%. 1H NMR (400 MHz, CDCl3) δ (ppm): 1.21-1.27 (42H, m, CH3), 2.70-2.75 and
2.91-2.94 (64H, m, -C(=O)-CH2-CH2-C(=O)-), 2.82 (64H, s, CH2 in NHS ring), 3.63 (m, CH2 in PEG backbone), 4.18-4.24 (56H,
m, -CH2-O-dendron generation 1,2 and 3). 13C NMR (100 MHz, CHCl3) δ (ppm): 16.76, 17.03, 24.95, 25.46, 27.79, 45.66,
45.97, 64.95, 69.90, 167.34, 168.96, 170.13 and 171.31.
Synthesis of DLD-8k-G3-Allyl (17)
DLD-8k-G3-OH (8) (10.0 g, 1 mmol), DMAP (0.4 mg, 6.6 mmol) and pyridine (3.7 ml, 0.1 mol) were dissolved in DCM (100.0
ml). The solution was placed on an ice bath and allyloxy anhydride (16) (9.6 g, 0.03 mol) was slowly added to the system.
Following the general anhydride coupling procedure, the product was collected as a white powder. Yield: 11.5 g, 88%. 1H
NMR (400 MHz, CDCl3) δ (ppm): 1.21-1.27 (42H, m, CH3), 2.62-2.65 (64H, m, -C(=O)-CH2-CH2-C(=O)-), 3.63 (m, CH2 in PEG
backbone), 4.00-4.02 (32H, m, -C(=O)-O-CH2-CH2-O-), 4.00-4.24 (88H, m, -C(=O)-O-CH2-CH2-O- and -CH2-O-dendron
generation 1,2 and 3), 5.17-5.30 (32H, q, CH=CH2) and 5.84-5.94 (16H, m, CH=CH2). 13C NMR (100 MHz, CHCl3) δ (ppm):
16.97, 28.09, 45.64, 63.09, 64.52, 67.06, 71.18, 116.38, 133.86, 170.80 and 171.25.
Synthesis of DLD-8k-G3-Alk (19)
DLD-8k-G3-OH (8) (10.0 g, 1 mmol), DMAP (0.4 mg, 6.6 mmol) and pyridine (3.7 ml, 0.1 mol) were dissolved in DCM (100.0
ml). The solution was placed on an ice bath and pentynoic anhydride (18) (4.4 g, 25 mmol) was slowly added to the system.
Following the general anhydride coupling procedure, the product was collected as a white powder. Yield: 10.1 g, 89%. 1H
NMR (400 MHz, CDCl3) δ (ppm): 1.24-1.29 (42H, m, CH3), 1.98-2.07 (16H, t, C≡CH), 2.46-2.57 (64H, m, -O-C(=O)-CH2-CH2-C≡),
3.63 (m, CH2 in PEG backbone) and 4.20-4.27 (56H, m, -CH2-O-dendron generation 1,2 and 3). 13C NMR (100 MHz, CHCl3) δ
(ppm): 13.32, 16.61, 16.87, 32.17, 45.45, 45.77, 64.33, 68.96, 69.61, 81.48, 170.06, 170.52, 170.93 and 171.02.
Figure S1 1H-NMR spectra of for a) DLD-8k-G3-OH (8), b) DLD-8k-G3-Alk (18), c) DLD-8k-G3-Allyl (17) and d) DLD-8k-G3-NHS (15)
Functionalization of di-functional linear crosslinkers
The functionalization of linear crosslinker is displayed in Scheme 1.
Scheme S2 Functionalization of linear PEG.
Synthesis of L-6k-N3 (24)
PEG-6k-OH (20) (10.0 g, 0.41 mmol), DMAP (0.1 mg, 0.67 mmol) and pyridine (0.8 ml, 0.02 mol) were dissolved in DCM
(50.0 ml). The solution was placed on an ice bath and 6-azidohexanoic anhydride (23) (0.9 g, 13 mmol) was slowly added to
the system. Following the general anhydride coupling procedure, the product was collected as a white powder. 1H NMR
(400 MHz, CDCl3) δ (ppm): 1.36-1.44 (4H, m, -CH2-N3), 1.57-1.69 (8H, m, -CH2-CH2-CH2-N3), 2.32-2.36 (4H, t, -O-C(=O)-CH2CH2-), 3.25-3.28 (4H, t, -O-C(=O)-CH2-CH2- ), 3.44-3.82 (m, CH2 in PEG backbone) and 4.20-4.23 (4H, t, -(O=)C-O-CH2-PEG
chain). 13C NMR (100 MHz, CHCl3) δ (ppm): 23.93, 25.72, 28.10, 33.44, 50.74, 63.04, 68.66, 70.11 and 172.81.
Synthesis of L-6k-BOC (26)
PEG-6k-OH (20) (3.0 g, 0.5 mmol), DMAP (25.0 mg, 0.2 mmol) and pyridine (0.2 ml, 3 mmol) were dissolved in DCM (20.0
ml). The solution was placed on an ice bath and β-alanine-BOC anhydride (23) (0.5 g, 15 mmol) was slowly added to the
system. Following the general anhydride coupling procedure, the product was collected as a white powder. Yield = 2.9 g,
91%. 1H NMR (400 MHz, CDCl3) δ (ppm): 1.40 (18H, m, -CH3), 2.53-2.56 (4H, m, -CH2-CH2-NH-), 3.36-3.41 (4H, t, -O-C(=O)CH2-CH2-), 3.44-3.80 (m, CH2 in PEG backbone) and 4.23-4.26 (4H, t, -(O=)C-O-CH2-PEG chain).
Synthesis of L-6k-NH3+ (27)
L-6k-BOC (26) (2.9 g, 0.5 mmol) was dissolved in DCM (50.0 ml) and TFA (5 ml) was added to the reaction vial and let react
for 1 hour. The completion of deprotection was monitored by Thin Layer Chromatography (TLC) plate in ether. The product
was purified by precipitation in ether and was collected as a slightly yellow power. Yield = 2.2 g, 75%. 1H NMR (400 MHz,
CDCl3) δ (ppm): 2.75-2.84 (4H, t, -CH2-CH2-NH3+), 3.28-3.32 (m, -CH2-CH2-NH3+), 3.30-3.80 (m, CH2 in PEG backbone) and
4.29-4.32 (4H, t, -(O=)C-O-CH2-PEG chain). 13C- NMR (100 MHz, CHCl3) δ (ppm): 31.24, 35.62, 63.80, 68.47, 70.30, 160.36
and 170.42.
General procedure of network formation
Thiol-ene, thiol-yne, CuAAC and amine-NHS are the four crosslinking chemistries utilized in this work. The synthesized
DLD polymers were crosslinked with complementary dual functional linear PEG crosslinkers as well as bio-based functional
cellulose nanocrystal and protein-based bovine serum albumin. Both balanced ratios between the components and off
stoichiometric ratios were explored to generate neutral as well as functional hydrogels. Table 2 reports the process of each
film formation. The materials theoretical molecular weights were used for molar estimations in network formations. All
hydrogels were fabricated in three replicas for swelling/leaching tests and five replicas for compression test.
Formation of thiol-ene networks
DLD-8k-G3-Allyl (17) was first dissolved in EtOH and L-6k-SH (22) was later added together with deionized water. The
final concentration was 50% dry weight in mixture of water:EtOH (1:1). The EtOH mixture was vortexed and the aqueous
solution of lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) (0.01 wt % of solid content) was added as the
photoinitiator as a final step. The solution was transferred to a Teflon mould and exposed to 365 nm-UV lamp with the
dosage of 5.4 W/m2 (10 minutes, intensity I= 9mW/m2). Three different allyl:thiol molar ratios (1:1, 1.5:1 and 1:1.5) were
chosen to form the networks.
The copolymerization between DLD-8k-G3-Allyl (17) and thiol functionalized nanocrystal cellulose (SH-CNC) was
performed by first dissolving the DLD-8k-G3-Allyl (17) followed by the addition of SH-CNC dispersed in deionized water. The
mixture was ultrasonicated for 10 minutes and the aqueous solution of the photoinitiator (LAP) (2wt % of dry components)
was added as a last step. The final concentration was 20% dry weight in mixture of water:EtOH (1:1). The mixture was
transferred to a Teflon mould and exposed to 365 nm-UV lamp with the dosage of 5.4 W/m2 (10 minutes, intensity I=
9mW/m2).
Formation thiol-yne networks
Networks from DLD-8k-G3-Alk (18) with L-6k-SH (22) and DLD-8k-G3-Alk (18) with SH-CNC were constructed following
the same procedure as thiol-ene networks. Note that stoichiometric ratio was calculated based on alkyne as di-functional
linear PEGs. For hydrogel formation, three different alkyne:thiol molar ratios (1:2, 1:1.3 and 1:2.5) were chosen to form the
networks.
Formation of CuAAC networks
DLD-8k-G3-Allyl (17) was first dissolved in EtOH. L-6k-N3 (24) and NaAsc (0.13 eq molar to alkyne) were later added
together with deionized water. The final concentration was 50% dry weight in mixture of water:EtOH (1:1). The mixture
was vortexed and an aqueous solution of Cu(II)SO4 (0.065 eq molar to alkyne) was added as a final step. The concentration
was 50% dry weight in water. The mixture was immediately transferred to the Teflon mould and allowed to generate the
networks overnight. Three different alk:N3 molar ratios (1:1, 1.5:1 and 1:1.5) were chosen to form the networks.
Formation of NHS-amine networks
DLD-8k-G3-NHS (15) and L-6k-NH3+ (27) were dissolved together in deionized water. The mixture was vortexed and an
aqueous solution of NaCO3 (1 eq molar to amine) was added and as a last step. The final concentration was 50% dry weight
in water and pH was noted to be between 7.5-8.2. Three different NHS:NH3+ molar ratios (1:1, 1.5:1 and 1:1.5) were chosen
to form the networks.
The hybridization of DLD-8k-G3-NHS (15) and protein-based material was accomplished by dissolving DLD-8k-G3-NHS
(15) and bovine serum albumin (BSA) in deionized water. The aqueous solution of NaCO 3 (1 eq molar to amine) was added
and well mixed as a last step. The final concentration was 15% dry weight in mixture of water and the mixture pH was
detected to 7.5 - 8.2.
Swelling and gel fraction
For swelling and leaching tests, the hydrogel networks were immersed in deionized water except CC gels which were
swollen in 0.1 M aqueous solution of EDTA to remove the residual copper. The completion of each leaching test was
confirmed by leaching hydrogels in deuterium and analysed by 1H-NMR to verify the absence of extractable compounds.
After that, the samples were freeze dried. The definitions of % swelling and gel fraction are as followed;
%𝑠𝑤𝑒𝑙𝑙𝑖𝑛𝑔 = (
𝑚𝑠𝑤𝑜𝑙𝑙𝑒𝑛−𝑚𝑙𝑒𝑎𝑐ℎ𝑒𝑑
𝑚𝑙𝑒𝑎𝑐ℎ𝑒𝑑
𝑔𝑒𝑙 𝑓𝑟𝑎𝑐𝑡𝑖𝑜𝑛 = 1 − (
) × 100
𝑚𝑖𝑛𝑖𝑡𝑖𝑎𝑙 −𝑚𝑙𝑒𝑎𝑐ℎ𝑒𝑑
𝑚𝑖𝑛𝑖𝑡𝑖𝑎𝑙
)
(1),
(2)
where, mswollen, mleached and minitial are weights of the sample in swollen, dry state (after leaching) and initial dry state (before
leaching).
Network postfunctionalization
Series of hydrogels fabricated from thiol-yne coupling were selected to demonstrate post modification via mild CuAAC in
water. Unleached gel (120 mg) was swollen in 2 ml aqueous solution of azide-functionalized rhodamine B (9 mg, 15 μmol)
and NaAsc (5.9 mg, 30μmol). The hydrogel was allow to swell in the postfunctionalization solution for 1 hour and and
Cu(II)SO4 (3.8 mg, 15 μmol) was added and the reaction was allowed to react for another 1 hour. The obtained hydrogel was
purged with deionized water and methanol until no coloured leachable were detected.
SEC curve
L-8k-OH (1)
DLD-8k-G1-OH (4)
DLD-8k-G2-OH (6)
DLD-8k-G3-OH (8)
DLD-8k-G3-Allyl (17)
Figure S2: SEC curve for DLD hybrids materials
Functionalization of linear PEG
Figure S3: MALDI and NMR spectra of functionalized linear PEG.