Facile Formation of Uniform Shell‐Crosslinked Nanoparticles with Built‐in Functionalities from N‐Hydroxysuccinimide‐Activated Amphiphilic Block Copolymers

Abstract

An amphiphilic block copolymer, poly(methylacrylate)82‐block‐poly(N‐(acryloyloxy)succinimide0.29‐co‐(N‐acryloylmorpholine)0.71)155 (PMA82‐b‐P(NAS0.29‐co‐NAM0.71)155), was synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization and then was supramolecularly assembled into micelles in aqueous solution, followed by chemical crosslinking throughout the shell region upon the introduction of 2,2′‐(ethylenedioxy)‐bis(ethylamine) as a crosslinker to afford well‐defined shell crosslinked nanoparticles (SCKs). The number‐averaged hydrodynamic diameters of the micelles and SCKs were (17 ± 4) nm and (16 ± 3) nm, respectively, by dynamic light scattering (DLS), and (15 ± 2) nm and (13 ± 2) nm, respectively, by transmission electron microscopy (TEM). In an attempt to narrow the particle size distributions, the dodecyl trithiocarbonate chain end of the block copolymer was replaced by a 2‐cyanoisopropyl moiety. Each nanoparticle system was characterized by DLS, electrophoretic light scattering (ELS), TEM, and small‐angle X‐ray scattering (SAXS). SAXS was of particular importance, as it provided definitive observation and quantification of shell contraction and densification upon shell crosslinking. The direct incorporation of NAS into the block copolymers during their preparation allowed for unique crosslinking chemistry to proceed with added diamino crosslinkers. The primary advantages of this system include the ability to conduct in situ synthesis of SCKs that are crosslinked directly and derivatized easily by adding nucleophilic ligands before, during, or after the crosslinking.

Living Radical Polymerization by the RAFT Process - A Second Update

“…MMA [296] St [296] 128* [283] S S C 12 H 25 S CO 2 H AA [91] CA [297] tBA [298] MA [299] (BMA) [300] (BMA) [300] CMA [301] MMA [122,283] (MMA) [122] BAM [302] DEAM [302,303] DMAM [302,303] EMAM [302,303] NIPAM [302][303][304][305][306] PAM [302,306] MVK [307] PVK [307] 297 [308] tBS [276] CMS [309] HMS [309] St [91,300,309] (St) [300] 4VP [310] Ip [311] 320 [312] 325 [100] 327 [309] 331 [313] 332 [313] NVP [103] 331-b-St [313] tBA-b-Ip [298] tBA-b-St [298] tBA-b-IP-b-St …”

“…Styrene derivatives subjected to RAFT polymerization 348 [100,199] O 349 [138] O N N N 350 [158,309] N VBTAC 351 [159] Cl Ϫ Nϩ 352 [459] HN O 353 [321] O F F F F 354 [313] O F F F F 355 [313] [244] VBTPC 359 [34] Cl Ϫ P ϩ 360 [244] 361 [250] O N O 362 [207] O O O 363 [134] O O O Fe 364 [102] N 365 [102] N Table 23. Vinyl derivatives subjected to RAFT polymerization 366 [380] N 367 [380] N 368 [380] N 369 [390] N O O G. Moad, E. Rizzardo, and S. H. Thang [111,135] 370 [135,146] 375 [136] 376 [195] 377 [150] 378 [410] O O (H 3 C) 3 Si 372 [338,346,347] 373 [201] 374 [459] O [466] NAS 380 [160,299,317,345,347] 381 [178] 382 [222] [149,…”

“…It was reported that aminolysis of PNIPAM trithiocarbonate proceeds quantitatively to the thiol when conducted in the presence of a [370] MMA Ph (28) AIBN [173] MMA Ph (28) 393 [173] MMA C 10 H 7 (42) AIBN B [194] 416 Ph (25) ACVA C [164,474] DMAPMAM Ph (25) AIBN [168] NIPAM C 2 H 5 S (185) 394 [368] NIPAM C 2 H 5 S (189) 394 [374] NIPAM C 12 H 25 S (139) AIBN [324] NIPAM S(PDMAM-b-PNIPAM) (398) AIBN [475] DMAM S(PDMAM) (398) AIBN [475] NAM/NAS C 12 H 25 S (115) AIBN [299] St Ph (24) AIBN [133] St C 4 H 9 S (160) AIBN D [473] St Ph (50) 395 [476] St S(PSt) (398) AIBN [475] VAc small amount of a phosphine reducing agent (TCEP). [371,372] Two groups have compared aminolysis with borohydride reduction for PSt dithiobenzoate.…”

“…[520] A variety of methods have been used to synthesize AA-b-St Diamine/carbodiimide crosslinking of PAA shell [200] AA-b-St 373 Diamine/carbodiimide of PAA shell [201] tBA-b-338 [235] Diamine/carbodiimide crosslinking of PAA shell [235] DMAM-b-331-b-NIPAM Ionic crosslinking of P331 shell with cationic PVBTAC [159] DMAM-b-(NIPAM/339) Ionic crosslinking of P(NIPAM/P339) shell with cationic PVBTAC [319] DMAEMA-b-NIPAM Au crosslinking of PDMAEMA shell [143] MA-b-NAS/NAM Diamine crosslinking of active ester in NAS/NAM shell [299] St/MAH-b-Ip Radical crosslinking (AIBN) of PIp shell [315] PEG-b-(CEA/DEMEMA) Photo-crosslinking of P(CEA/DEMEMA) core [515] A See footnote A of Table 3. B See footnote B of Table 3. silica-bound RAFT agent functionality for surface-initiated grafting (Table 36).…”

Synthesis of well‐defined polymeric activated esters

“…It has been Wooley and coworkers, who finally took advantage of the defined polymeric activated esters in a supramolecular assembly process. 44 They described the synthesis of an amphiphilic copolymer (PMA-b-P(NHSA-co-NMA)) via RAFT polymerization and the resulting amphiphilic copolymers self-assembled into micelles in aqueous solution. A subsequent chemical crosslinking of activated esters in the shell region with a diamine afforded shell crosslinked nanoparticles.…”