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In this paper, we proposed a heteroatom substitution strategy (HSS) in the δ‐valerolactone (VL) system to modulate thermodynamics toward chemically recyclable polyesters. Three VL‐based monomers containing different heteroatoms (M1 (N), M2 (S), and M3 (O)), instead of C‐5 carbon, were designed and synthesized to verify our proposed HSS. All three monomers undergo organocatalytic living/controlled ROP and controllable depolymerization. Impressively, the resulting P(M1) achieved over 99 % monomer recovery under both mild solution depolymerization and high vacuum pyrolysis conditions without any side reactions, and the recycled monomers can be polymerized again forming new polymers. The systematic study of the relationship between heteroatom substitution and recyclability shows that introducing heteroatoms does change the thermodynamics of the monomers (ΔHpo, ΔSpo and Tc values), thereby adjusting the polymerizability and depolymerizability. DFT calculations found that the introduction of heteroatoms adjusts the ring strain by changing the angular strain of the monomers, and the order of their angular strain (M2>M1>M3) is consistent with the order of the experimentally obtained enthalpy change. Notably, the one‐pot/one‐step copolymerization of two of each of the three monomers enables the synthesis of sequence‐controlled copolymers from gradient to random to block structures, by simply switching the copolymerization temperature. [ABSTRACT FROM AUTHOR]

Rational design of monomer sequence for desired properties is challenging. This study investigates the effect of monomer distribution of double hydrophilic copolymers (DHCs) with electron‐rich units on cluster triggered emission (CTE) capacity. By means of combining latent monomer strategy, reversible addition fragmentation chain transfer (RAFT) polymerization and selective hydrolysis technology, the random, pseudo di‐block and the gradient DHCs consisting of pH‐responsive polyacrylic acid (PAA) segments and thermo‐responsive poly(N‐isopropylacrylamide) (PNIPAM) segments were successfully synthesized in a controlled manner. Moreover, the gradient DHCs showed a tremendously increased luminescent intensity due to the distinct hydrogen‐bonding interaction compared to random and pseudo di‐block DHCs. To the best of our knowledge, this is the first reported the direct correlation between luminescent intensity and sequence structure of non‐conjugated polymer. Meanwhile, thermo and pH dual‐responsive clusteroluminescence could be easily performed. This work demonstrates a novel and facile method to tailor the hydrogen‐bonding for the stimuli‐responsive light‐emitting polymers. [ABSTRACT FROM AUTHOR]

Polypeptoids, structural mimics of polypeptides, have attracted considerable attention due to their biocompatibility, proteolytic stability, thermal processability, good solubility, synthetic accessibility, and structural diversity. Polypeptoids have emerged as an interesting material in both polymer science and biological field. This review primarily discusses the research progress of polypeptoids prepared by controlled ring‐opening polymerizations in the past decade, including synthetic strategies of monomers, polymerizations by different initiators, postfunctionalization, fundamental properties, crystallization‐driven self‐assembly, and potential biological applications. [ABSTRACT FROM AUTHOR]

Sequence control has attracted increasing attention for its ability of regulating polymer property and performance. Herein, the sequence‐controlled polymer containing acrylonitrile (AN) is achieved by using 2,5‐dimethylfuran/acrylonitrile adduct as a latent monomer. The temperature‐dependent retro Diels–Alder reaction is engaged in controlling the release of AN during RAFT polymerization, that is, regulating the instant AN concentration via a non‐invasive and in situ manner. Such control over the instant AN concentration and particularly the molar ratio of comonomer pair leads to the simultaneous change of monomer units in "living" polymeric chain, thus resulting in the sequence–controlled polymeric structures. By delicately manipulating the polymerization temperature, diverse sequence‐on‐demand structures of AN‐containing copolymers, such as poly(AN/methyl methacrylate), poly(AN/styrene), poly(AN/butyl acrylate), poly(AN/N,N‐dimethylacrylamide), and poly(AN/N‐isopropylacrylamide) are created. Meanwhile, this study presents an initial attempt in tuning the thermal responsivity of poly(AN/N‐isopropylacrylamide), which is closely correlated to the sequence of polymer structure. More importantly, the polymer with averagely distributed AN units results in the higher thermal sensitivity. Therefore, the synthetic strategy proposed in this work offers a promising platform for accessing the sequence‐controlled copolymers containing AN structures, thus expanding the investigation on the relationship between the polymer structures and correlated properties. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: The on‐demand building copolymer structures, from sequence to architecture, is crucial in understanding the relation between polymer structure and property, meanwhile motivating the innovation of polymer hierarchy. However, the challenge is conspicuous for complicated polymer structures from inherently intricate polymerization. In this work, copolymers with tailored grafting density and distributions were achieved using successive latent monomer and grafting‐from strategies. The hydroxyl group functionalized furan/maleimide adduct (FMOH) was selected as the latent monomer for RAFT polymerization of an array of copolymers with tailored localization of hydroxyl group along the main chain. The hydroxyl group further initiated the ring opening polymerization (ROP) of L‐lactide or ε‐caprolactone, resulting in a library of multicomponent copolymers via grafting‐from strategy. The initiating efficiency reached to ~100% with variable molecular weight (21300—58600 Da) and narrow distributions (ÐM < 1.25), indicating that such graft copolymers possessed controlled density and distribution of side chains as its linear template. The investigation on thermal properties of the well‐defined graft copolymers implied that the precise tailoring over copolymer structures at the molecule level could lead to tunable chemical/physical properties. This work bridged polymer from sequence to architecture, unveiled a new method in creating graft copolymers with programmable structures and provided the insight into the structure/property relationship. [ABSTRACT FROM AUTHOR]

Herein, a novel methodology for preparing sequence-controlled polymers is illustrated by using a latent monomer, furan protected maleimide (FMI). At 110 °C, FMI is deprotected by retro Diels-Alder (rDA) reaction, and the released MI is immediately involved in the cross-polymerization with styrene (St) to deliver heterosegments. At 40 °C the rDA reaction does not proceed, therefore homo-poly(styrene) segments are produced. By implementing programmable temperature changes during polymerization of St and FMI, 'living' polymers with tailored a sequence are created. A ternary copolymerization produces complex sequences as designed. Alkynyl-functionalized FMI, used as a latent monomer, leads to the desirable placement of functional groups along the polymer chain. This latent-monomer-based strategy opens a new avenue for fabricating sequence-controlled polymers. [ABSTRACT FROM AUTHOR]

A novel Janus compound containing azo-based thermal initiator and bromo-based atom transfer radical polymerization (ATRP) initiator group is synthesized. Such compound can be applied in the living radical polymerization of alkyl methacrylate monomers, such as methyl methacrylate, tert-butyl methacrylate, and 2-( N, N-dimethylamino) ethyl methacrylate. Polymers with controlled molecular weights and narrow molecular weight distributions are obtained. The structure of polymers is identified by 1H NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrum. A modified initiator for continuous activator regeneration ATRP mechanism is proposed according to the polymerization behavior, hydrolysis of chain backbone, and end group identification. [ABSTRACT FROM AUTHOR]

Ring-opening copolymerization (ROCOP) is an effective means to prepare functionalized polyester. In this work, a type of selenide-containing polyesters with controllable structure, molecular weight, and molecular weight distribution was successfully prepared by ROCOP of γ-selenobutyrolactone and epoxy compounds. The influence of the catalyst, solvent, and reaction temperature on the reaction efficiency was examined. Then, kinetic study was investigated under an optimized condition. The structure of the copolymers was carefully characterized by nuclear magnetic resonance (NMR), 1H NMR, 13C NMR, and 77Se NMR, Matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and size exclusion chromatography (SEC). The resulting polymers showed a linear structure with a sequence regulated backbone repeating unit of ester-selenide. On this basis, some typical epoxides were investigated to verify the scope of the polymerization system. Due to the "living"/controlled characteristics of this ROCOP, multiblock, amphiphilic, and stereotactic copolymers could be prepared with a pre-designed structure. As expected, the selenide-containing amphiphilic copolymer could self-assemble to micelles and showed an oxidative response. [ABSTRACT FROM AUTHOR]

The photocatalyst Zn(II) meso‐tetra(4‐sulfonatophenyl)porphyrin (ZnTPPS) is found to substantially accelerate visible‐light‐initiated (red, yellow, green light) single unit monomer insertion (SUMI) of N,N‐dimethylacrylamide into the reversible addition–fragmentation chain transfer (RAFT) agent, 4‐((((2‐carboxyethyl)thio)carbonothioyl)thio)‐4‐cyanopentanoic acid (RAFT1), in aqueous solution. Thus, under irradiation with red (633 nm) or yellow (593 nm) light with 50 mpm (moles per million mole of monomer) ZnTPPS at 30 °C, the rate enhancement provided by photoinduced energy or electron transfer (PET) is ≈sevenfold over the rate of direct photoRAFT‐SUMI (without catalyst), which corresponds to achieving full and selective reaction in hours versus days. Importantly, the selectivity, as judged by the absence of oligomers, is retained. Under green light at similar power, higher rates of SUMI are also observed. However, the degree of enhancement provided by PET‐RAFT‐SUMI over direct photoRAFT‐SUMI as a function of catalyst concentration is less and some oligomers are formed. [ABSTRACT FROM AUTHOR]

Abstract: Well-defined photo-responsive alternating copolymers, poly(4-(N-maleimido)azobenzene-alt-styrene)s (PMSts), were successfully synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. A divinyl monomer was used in this polymerization to prepare high molecular weight azobenzene polymers. These polymers had good solubility in most organic solvents, formed films well, and had high glass transition temperatures (T g =174–250°C) and were heat resistant (T d >320°C). The photo-induced trans–cis isomerization of the copolymers was examined in chloroform solution. Surface-relief-gratings (SRGs) formed on the polymer films were also investigated using illumination from a linearly polarized Kr+ laser beam. [Copyright &y& Elsevier]

Abstract: A novel monomer containing triazole and naphthalene ring, 2-(1-naphthalen-1-ylmethyl-1H-[1,2,3]triazol-4-yl)-ethyl methacrylate (NTEMA), was designed and synthesized via “click” chemistry method. The RAFT polymerization of NTEMA was successfully carried out using 2-cyanoprop-2-yl dithiobenzoate (CPDB) as a RAFT agent, 2,2′-azobisisobutyronitrile (AIBN) as an initiator in tetrahydrofuran (THF) solution. The results showed that the polymerizations exhibited “living”/controlled characteristics. The obtained poly(2-(1-naphthalen-1-ylmethyl-1H-[1,2,3]triazol-4-yl)-ethyl methacrylate) homopolymers, PNTEMAs, were further coordinated with samarium ion to prepare rare earth containing polymers (PNTEMA–Sm(III) complexes) which were characterized by FT-IR, DSC and ICP-AES. The characterization data confirmed that triazole in side chain of the polymer could coordinate with Sm(III). The fluorescence property of the polymers and polymer Sm(III) complexes were investigated in solution and in film. [Copyright &y& Elsevier]

Main observation and conclusion: The on‐demand building copolymer structures, from sequence to architecture, is crucial in understanding the relation between polymer structure and property, meanwhile motivating the innovation of polymer hierarchy. However, the challenge is conspicuous for complicated polymer structures from inherently intricate polymerization. In this work, copolymers with tailored grafting density and distributions were achieved using successive latent monomer and grafting‐from strategies. The hydroxyl group functionalized furan/maleimide adduct (FMOH) was selected as the latent monomer for RAFT polymerization of an array of copolymers with tailored localization of hydroxyl group along the main chain. The hydroxyl group further initiated the ring opening polymerization (ROP) of L‐lactide or ε‐caprolactone, resulting in a library of multicomponent copolymers via grafting‐from strategy. The initiating efficiency reached to ~100% with variable molecular weight (21300—58600 Da) and narrow distributions (ÐM < 1.25), indicating that such graft copolymers possessed controlled density and distribution of side chains as its linear template. The investigation on thermal properties of the well‐defined graft copolymers implied that the precise tailoring over copolymer structures at the molecule level could lead to tunable chemical/physical properties. This work bridged polymer from sequence to architecture, unveiled a new method in creating graft copolymers with programmable structures and provided the insight into the structure/property relationship. [ABSTRACT FROM AUTHOR]

Abstract Herein, we designed and synthesized functional maleimide containing "clickable" or hydrophilic functional groups that was used to synthesis advanced sequence-controlled functional polymers via latent monomer strategy. A number of sequence-controlled functional polymers were synthesized by changing the polymerization temperature and controlling the initial charge ratio with highly programmable controlled temperature. Finally, a preliminary study on the thermal properties of the obtained sequence-controlled polymer revealed that the content and the distribution of the hydrophilic monomer in the polymers have a profound effect on the properties of the polymers. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract: The light sensitive vinyl monomer with coumarin unit, 7-(4-(acryloyloxy)butoxy)coumarin (7AC), was synthesized. The reversible addition–fragmentation chain transfer (RAFT) polymerization of 7AC, initiated by 2,2′-azobisisobutyronitrile (AIBN), was carried out using 2-cyanoprop-2-yl dithiobenzoate (CPDB) as a RAFT agent in N,N-dimethylformamide (DMF) solution. The kinetics exhibited first-order relationship with respect to the monomer concentration. The molecular weight of the polymer increased linearly with the monomer conversion. The chain extension of poly(7-(4-(acryloyloxy)butoxy)coumarin) (P7AC) using styrene (St) as the second monomer demonstrated that the obtained polymers were almost “living”. The fluorescence intensity of P7AC increased with the molecular weight of P7AC and was stronger than that of the monomer. The obtained polymer had strong ultraviolet (UV) absorption at 322nm. The molecular weights of the polymer had no effect on its ultraviolet absorption intensity. The coumarin structure existing in P7AC underwent [2+2] cycloaddition reaction (photodimerization) under UV irradiation in tetrahydrofuran (THF) solution, which can be further used to prepare small particles from the single polymer. [Copyright &y& Elsevier]

Abstract: A novel benzodithioate compound with a pyrene structure in the R group, pyrenylmethyl benzodithioate (PMB) was synthesized. Using PMB as the chain transfer agent (CTA), the RAFT polymerizations of styrene with AIBN as an initiator were carried out in different reaction conditions. The results indicated that PMB was an effective CTA for the RAFT polymerizations of styrene with the “living”/controlled characteristics. The structures of the obtained polymers were characterized by 1H NMR. The results showed that majority of the polymer chains contained the pyrene moiety in the chain end. The enhanced fluorescence property in CHCl3 solution was observed. The chain-extension experiments of the obtained polystyrene (PS) with the monomers of styrene and methyl acrylate were successfully carried out. [Copyright &y& Elsevier]