Block copolymers via macromercaptan initiated ring opening polymerization

Abstract

Poly(styrene) macromercaptanes (Mn = 1900, 3600, and 6100 g mol−1, PDI ≈ 1.2) derived from thiocarbonyl thio capped polymers prepared via reversible addition fragmentation chain transfer polymerization were employed to initiate the ring opening polymerization (ROP) of D,L‐lactide under conditions of organo‐catalyis employing 4,4‐dimethylaminopyridine. Poly(styrene)‐block‐poly(lactide) polymers of number average molecular weights up to 25,000 g mol−1 (PDI ≈ 1.2 to 1.6) were obtained and characterized via multiple detection size exclusion chromatography (SEC) using refractive index as well as UV detection. In addition, diffusion ordered nuclear magnetic resonance and liquid chromatography at critical conditions (of both polystyrene as well as poly(lactide) were employed to assess the copolymers' structure. Furthermore, it was demonstrated that polyethylenes capped with a thiol moiety can also be readily chain extended in a ROP employing D,L‐lactide, evidenced via NMR and high temperature SEC. This study indicates that the direct use of macromercaptantes is indeed a methodology to switch from a radical to a ROP process. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

RAFT Polymerization and Thiol Chemistry: A Complementary Pairing for Implementing Modern Macromolecular Design

“…An amine mechanism was proposed for the initiation, where an amine is produced after the first attack of the thiol onto an N-carboxyanhydride. Similarly, thiol-terminated PS has been employed to initiate the ROP of D,L-lactide by Lefay et al [90] under 4,4-dimethylaminopyridine catalysis (Scheme 3D). Multiblock and hyperbranched PMA was prepared by Xu et al via thio-bromo click chemistry.…”

“…Thiol terminated polymers have also been used to produce diblock copolymers, either by using an eneterminated second polymer, such as PEG acrylate, [71] or by performing two consecutive thiol-ene reactions with a Overview of different architectures realized through thiol end-group chemistries. A) Formation of three-armed stars through nucleophilic addition onto a core molecule, [84] B) Formation of hairy nanoparticles through a radical addition onto vinyl modified particles, [85] C) Formation of graft polymers through (co)polymerizing macromonomers, [74] and D) Formation of diblock copolymers through a thiol initiated ROP of lactic anhydrides [31] or N-carboxy-anhydrides. [30] See Table 1 for definition of Y.…”

“…[29] The products of such substitution reactions are thioethers. Thiols can be added to N-carboxyanhydrides [30] or D,Llactide [31] by ring opening the anhydride thus forming a thioester linkage (Table 1). …”

Living Radical Polymerization by the RAFT Process – A Third Update

“…[44] The first reports involved the use of N,N-dialkyl dithiocarbamate derivatives as ATRP initiators. Dithiocarbamates do not provide effective control over the polymerization [241] MMA, St 456 Propylamine Network cleavage [603] BA, St 441 Butylamine/TCEP/BA In situ thiol-ene multiblock cleavage [604] PEGA 47 Butylamine/TCEP/divinyl sulfone In situ thiol-ene [281] MA, DMAm, NIPAm, St, C 2 H 5 S (121) Hydrazine - [375] St, PEGMA Ph (54, 18) Hydrazine - [375] St Ph (18) Hydrazine Used in thiol-epoxide [193] St Ph (18) DEAm (18) Hydrazine In situ thiol-epoxide [193] St/AcS Ph (11) Hydrazine Au nanoparticles [176] EGDMA, 421, 420 Ph (18) Hexylamine Used in thiol-ene or other reaction [588] St PhCH 2 S 1) KOH, 2) Zn/AcOH Au nanoparticles [338] St PhCH 2 S (89) Ethylene diamine Initiator for ROP C [339] HPMAm Ph (11) NaBH 4 /PBu 3 In situ thiol-ene (AA) [161] HPMAm Ph (68) Butylamine MeOH/degassed used in thiol-ene [307] NIPAm Ph (18) NaBH 4 Used in thiol-ene [247] MMA Ph (18) Hexylamine In situ thiol-ene [220] HPMAm Ph (18) Hexylamine In situ thiol-ene [220] NIPAm CH 2 (CO 2 H)CH 2 S (179) Hexylamine In situ thiol-ene [220] NIPAm C 4 H 9 S (159) Hexylamine/DMPP Used in thiol-ene [446] NIPAm C 12 H 25 S (123) Hexylamine/Bu 3 Ph Used in thiol-ene [398] Am Ph (18) NaBH 4 Used in thiol ene [244] DEAm Ph ( StMe OEt Ozone --(C¼O)SOEt [606] BA OEt Ozone --(C¼O)SOEt [607] iBoA 2-pyridyl Air AIBN, THF/Ph 3 P -OH [605] MMA, acrylates Ph Air AIBN, THF/Ph 3 P -OH [182,605] St, acrylates P n S Air AIBN, THF/Ph 3 P -OH [182] MA, BA CH 2 Ph Air AIBN, THF/Ph 3 P -OH [182] St CH 2 Ph Air AIBN, THF/Ph 3 P -OH …”

“…S S S A* [331,335] CMS [336] St [182,[337][338][339] tBS [337] AN [331] BA [182,274] DMAEA [221] MA [182] iBoA [182] tBA [182] ODA [337] 2EHA [337] PEGA [340] NVP [248] (VAc) [274] B/AN [312] DVE/MAH [341,342] PEGA-b-CIPEA [340] ODA-b-NIPAm [337] 2EHA-b-NIPAm [337] St-bNIPAm [337] tBS-b-NIPAm [337] (BA-b-VAc) [274] DVE/MAH-bSt [341,342] …”