Surface Modification of Poly(divinylbenzene) Microspheres via Thiol−Ene Chemistry and Alkyne−Azide Click Reactions

Abstract

We report the functionalization of cross-linked poly(divinylbenzene) (pDVB) microspheres using both thiol-ene chemistry and azide-alkyne click reactions. The RAFT technique was carried out to synthesize SH-functionalized poly(N-isopropylacrylamide) (pNIPAAm) and utilized to generate pNIPAAm surface-modified microspheres via thiol-ene modification. The accessible double bonds on the surface of the microspheres allow the direct coupling with thiol-end functionalized pNIPAAm. In a second approach, pDVB microspheres were grafted with poly(2-hydroxyethyl methacrylate) (pHEMA). For this purpose, the residual double bonds on the microspheres surface were used to attach azide groups via the thiol-ene approach of 1-azido-undecane-11-thiol. In a second step, alkyne endfunctionalized pHEMA was used to graft pHEMA to the azide-modified surface via click-chemistry (Huisgen 1,3-dipolar cycloaddition). The surface-sensitive characterization methods X-ray photoelectron spectroscopy, scanning-electron microscopy and FT-IR transmission spectroscopy were employed to characterize the successful surface modification of the microspheres. In addition, fluorescence microscopy confirms the presence of grafted pHEMA chains after labeling with Rhodamine B.

Living Radical Polymerization by the RAFT Process - A Second Update

“…tBA [283] 162 [339] S S C 4 H 9 S -C 163 [339] S S Ph N N N C 4 H 9 S BA [339] St [339] 164 [348] S S C 3 H 7 S MA [349] 165 [350] St [350] St-b-MA [350] 166 [351] S S C 4 H 9 S (BA) [351] (St) [351] (St-b-BA) [351] (BA-b-St) [351] 167 [337] S S C 6 H 13 S St [337] 168* [352] S S C 12 H 25 S 319 [352] (Continued) [283] St [283,353] 170 [283] S S S HO 2 C AA [354] DMAM [218] NIPAM [355] St [218,283] (St) [356] (SSO3Na) [167] DADMAC [357] 346 [358] AA-b-SSO3Na [354] 346-b-DMAM [358] (St-b-DMAM) [218] 171 [349] MA [349] MA-b-St [349] 172 [226] S S Br Ϫ N C 12 H 25 S ϩ St [226] 173 [227] 176 [350,360] POSS macro-RAFT agent…”

“…[117,130,479] This methodology has been applied to the synthesis of three-armed stars by an in-situ thiol-ene reaction with a triacrylate [130] and has been applied to directly make biopolymer conjugates. [479] A recent study shows that dithioester and trithiocarbonate RAFT agents [R-SC(S)Z] undergo a radical-catalyzed reaction with thiols that results in oxidation of the thiol to a disulfide and concomitant reduction of the RAFT agent to R-H. [481] The relative rates of reaction suggested that dithioester RAFT agents [204] PEGA Ph (58) Butylamine Used in thiol-ene [204] NIPAM SCH 2 CH(CH 3 ) 2 (188) Butylamine/TCEP/HEA butylamine/TCEP/BA One-pot thiol-ene [373] NIPAM SCH 2 CH(CH 3 ) 2 (188) Butylamine/TCEP Used in thiol-ene [371,372] NIPAM Ph (25) LiB(C 2 H 5 ) 3 H Used in thiol-ene [151] NIPAM S(CH 2 ) 2 CO 2 H (170) NaBH 4 Used in thiol-ene [355] NIPAM SC 4 H 9 (166) NaOH/MeOH/EDTA Used in thiol-ene [412] NIPAM Ph (24) Octylamine/DMPP/AMA One-pot thiol-ene [132] NIPAM Ph (24) Octylamine/DMPP/PMA One-pot thiol-ene [132] DEAM Ph (24) Hexylamine/DMPP/MA One-pot thiol-ene [130] St Ph (24) Propylamine/PBu 3 /MA NaBH 4 /PBu 3 /MA One-pot thiol-ene [117] St Ph (24) Propylamine NaBH 4 [205] MMA Ph (82) Hexylamine Conditions to favour disulfide formation [196] MMA Ph (22) Propylamine One-pot methanethiosulfonate [480] NVP OC 2 H 5 (228) NaBH 4 Used in peptide/nucleotide conjugation [396] A Monomer unit adjacent to thiocarbonylthio group. B TCEP -tris(2-carboxyethyl) phosphine hydrochloride, EDTA -ethylenediaminetetraacetic acid, TCEP -tris(2-carboxyethyl phosphine), DMPPdimethylphenylphosphine.…”

Porous polymer particles—A comprehensive guide to synthesis, characterization, functionalization and applications

“…Methacrylate crosslinkers are also polymerized via precipitation polymerization with a low percentage of added monomer [50][51]. As a result, precipitation polymerized particles are rich in remaining double bonds that can be efficiently utilized in post-functionalization [52] (see further functionalization section). As the polymerization starts, oligomers and nuclei are being formed (Fig.…”

“…A combination of thiol-ene and CuAAC click reactions on nonporous polyDVB particles was published by Müller et al [52]. Remaining double bonds of precipitation polymerized polyDVB particles first underwent thiol-ene click by treatment with 1-azidoundecan-11-thiol.…”

A Rapid One-Pot Synthesis of Novel High-Purity Methacrylic Phosphonic Acid (PA)-Based Polyhedral Oligomeric Silsesquioxane (POSS) Frameworks via Thiol-Ene Click Reaction

“…The second step for the synthesis of POSS-S-PA from POSS-SH is explained as follows: The methacrylic PA-terminated hybrid-network polymer POSS-S-PA was synthesized by the so-called "thiol-ene" reaction [19,23,24] using POSS-SH and EGMP. For synthesis, 10 mL of POSS-SH (10.1800 g, 1000 mL, and 10 mM) dissolved in 30 mL of anhydrous DCM and TEA (0.24 mM) were taken in a three-necked round bottom flask and subjected to constant stirring under an N 2 atmosphere for about 2 h at 40 • C. Then, freshly distilled EGMP (16.8080 g, 1000 mL, and 80 mM) was injected into the reaction mixture to carry out the polymerization reaction for 5 h at 40 • C. In order to retain the POSS-cage structure, EGMP was added slowly, dropwise, for up to 30 minutes.…”