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Me6TREN (tris[2‐(dimethylamino)ethyl]amine) is commonly used in Cu(0)‐mediated polymerization of acrylates due to its ability to promote high reaction rates while maintaining excellent control of chain growth. However, its cost presents a significant barrier to commercialization. Thus, the use of PMDETA (N,N,Nʹ,Nʹʹ,Nʹʹ‐pentamethyldiethylenetriamine), a ligand that is significantly less expensive than Me6TREN but is known to reduce the polymerization rate as well as control, is explored. The continuous production of low molecular weight (MW) poly(methyl acrylate) using PMDETA ligand in a copper tubular reactor is demonstrated, with conversions >70% achieved with a residence time of 32 min at 70 °C. The resulting macroinitiator solution can be stored and chain extended with methyl acrylate (MA) to high conversion in a semibatch reactor using either PMDETA or Me6TREN as additional ligand, increasing the versatility of a newly developed process to efficiently produce block copolymers using either ligand, or a combination of the two. First results suggest that the two‐step process can also be used to chain extend the macroinitiator with methacrylates, thus extending the range of materials that can be produced. [ABSTRACT FROM AUTHOR]

Postmodification methods are effective tools in preparing functional polymers, and novel end‐group reactions have attracted much attention from researchers for postmodification applications. Here, a new high‐efficiency postmodification method is proposed, which can change bromine‐containing polymers to functional polymers in one step. Phenol, 1‐hydroxynaphthalene, and 4‐(2‐phenyldiazenyl)‐phenol (AzoOH) are successfully grafted onto the polymeric branch chain of bromine‐containing polymers, i.e., homopolymer, bromoethyl methyl acrylate, (pBMEA) and amphiphilic block copolymer p(BMEA)‐b‐p(mPEG), with a high grafting rate that is near 100%. Also, the micelles of the postmodified amphiphilic block copolymer p(BMEA‐Azo)‐b‐p(mPEG) are broken up under ultraviolet irradiation. The proposed method can be used as a platform to prepare a variety of stimuli‐responsive polymeric nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: Temperature‐sensitive amphiphilic block copolymers of 2,2‐dimethyl‐1,3‐dioxolan‐4‐yl‐methyl acrylate (solketal acrylate, SKA) and N‐isopropyl acrylamide (NIPAAm) have been prepared via reversible addition‐fragmentation chain transfer radical polymerization (RAFT). A kinetics study of SKA polymerization is performed in order to find a compatible RAFT chain transfer agents (CTA) and versatile polymerization conditions for the synthesis of well‐defined poly(2,2‐dimethyl‐1,3‐dioxolan‐4‐yl‐methyl acrylate) (PSKA). Depending on the RAFT‐CTA and the reaction time, PSKA with molar masses up to 5700 g mol−1 and dispersity values as low as 1.1 could be prepared. Additionally, the end group distribution of PSKA is investigated via electrospray ionization‐ion mobility separation–mass spectrometry. The chain extensions of the homopolymers for the second block of NIPAAm are analyzed with size‐exclusion chromatography. Amphiphilic block copolymers are obtained after hydrolysis of hydrophobic PSKA block to target hydrophilic poly(2,3‐dihydroxypropyl acrylate) block. [ABSTRACT FROM AUTHOR]

Abstract: A one‐pot, two‐step method is applied to the controlled synthesis of polyacrylate‐b‐(polycaprolactone)2 three‐arm AB2‐type star block polymers. First, ring‐opening polymerization (ROP) of ε‐caprolactone is carried out in toluene using either stannous octoate (Sn(Oct)2) or diphenyl phosphate (DPP) as catalyst, and a multifunctional initiator featuring one bromoester and two alcohol groups. Then, single‐electron transfer living radical polymerization (SET‐LRP) of methyl acrylate and isobornyl acrylate is conducted in the same reaction vessel after sequential addition of its typical reactants, apart from the (PCL)2‐Br macroinitiator generated in the first step, in either toluene/toluene + phenol or toluene/dimethyl sulfoxide solvent systems. DPP (the ROP catalyst) from the first step is found to take part in an acid–base reaction with tris[2‐(dimethylamino)ethyl]amine (the SET‐LRP N‐ligand) in the second part, but stoichiometry could be adjusted to avoid interference and keep the controlled nature of the polymerizations. Interestingly, the electrochemically active Sn(Oct)2 ROP catalyst does not interfere with the SET‐LRP process. Well‐defined poly(methyl acrylate)‐b‐(polycaprolactone)2 and poly(isobornyl acrylate)‐b‐(polycaprolactone)2 are thus synthesized through a simple and cost‐effective experimental procedure. The technique also applies to the synthesis of linear block copolymers. [ABSTRACT FROM AUTHOR]

Reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene (St) and 4-(diphenylphosphino)styrene (DPPS) is explored to establish the statistical distribution of the phosphine-functional monomer within the copolymer. RAFT copolymerization of St and DPPS at a variety of feed ratios provides phosphine-functional copolymers of low dispersity at moderate monomer conversion ( Ð < 1.2 at conv. >60%). In all cases, the fraction of DPPS in the resulting polymers is greater than that in the monomer feed. Estimation of copolymerization reactivity ratios indicates DPPS has a strong tendency to homopolymerize while St preferentially copolymerizes with DPPS ( rDPPS = 4.4; rSt = 0.31). The utility of the copolymers as macro-RAFT agents in block copolymer synthesis is demonstrated via chain extension with hydrophilic acrylamide ( N, N-dimethylacrylamide (DMAm)) and acrylate (poly(ethylene glycol) methyl ether acrylate (mPEGA), and di(ethylene glycol) ethyl ether acrylate (EDEGA)) monomers. Finally, access to polymers containing phosphine oxide and phosphonium salt functionalities is shown through postpolymerization modification of the phosphine-containing copolymers. [ABSTRACT FROM AUTHOR]