Preparation of filled temperature-sensitive poly(N-isopropylacrylamide) gel beads

Temperature-sensitive filled poly(N-isopropylacrylamide) (PNIPAAm) gel beads with diameters in the range of millimeters were prepared using the alginate technique. The polymerization and cross-linking reaction of NIPAAm in the presence of inorganic filling particles was performed in spherical networks of Ca-alginate forming interpenetrating networks (IPN). Thermo-sensitive gel beads could be obtained by washing these IPN with EDTA solution. The PNIPAAm gel beads were analyzed by optical methods to observe there swollen diameter in dependence on the temperature. The diameters of the swollen gel beads were in the range of 0.1 - 2 mm. The influence of the monomer to cross-linker ratio (MCR) and the filling materials (ferrofluid, BaTiO₃, TiO₂, and Ni,) were studied. The phase transition temperature (T_pt) was only weakly influenced by the MCR and the filling material remaining at around 34°C.     

Thermoreversible nonlinear diels‐alder polymerization of furan/plant oil monomers

Novel trifunctional monomers based on renewable resources were prepared and subsequently polymerized via the Diels‐Alder (DA) polycondensation between furan and maleimide complementary moieties. Three basic approaches were considered for these nonlinear DA polycondensations, namely the use of (i) a bisfuran monomer in combination with a trismaleimide (A₂ + B₃ system) and (ii) a trisfuran monomer in conjunction with a bismaleimide (A₃ + B₂ system) leading to branched or crosslinked materials, and (iii) the use of monomers incorporating both furan and maleimide end groups (A₂B or AB₂ systems), which lead to hyperbranched structures. The application of the retro‐DA reaction to the ensuing polymers confirmed their thermoreversible character. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Epoxy/SiO2 interpenetrating polymer networks

We demonstrate a potentially useful method of generating an SiO₂ morphology, in situ, with interpenetrating polymer networks (IPN) chemistry. Organic/inorganic IPNs were synthesized with an organic phase made of epoxy resin and an SiO₂ phase made by sol—gel chemistry. The two types of polymerization used were sequential and simultaneous with SiO₂ content ranging from 0.02 to 0.43 g SiO₂/g total weight. The resultant morphologies were examined by small angle X-ray scattering and transmission electron microscopy. The sequential IPNs were strongly phase separated into a finely divided SiO₂ phase of ∼10 nm size scale. The simultaneous IPNs were weakly phase separated with considerable mixing in the phases. Thermal studies showed increased thermal stability for the IPNs, compared with unfilled epoxies or physically mixed silica filled epoxies.     

Sterically stabilized emulsion polymerization of styrene: Pseudo‐semicontinuous approach

The sterically stabilized emulsion polymerization of styrene initiated by a water‐soluble initiator at different temperatures has been investigated. The rate of polymerization (R_p) versus conversion curve shows the two non‐stationary‐rate intervals typical for the polymerization proceeding under non‐stationary‐state conditions. The shape of the R_p versus conversion curve results from two opposite effects—the increased number of particles and the decreased monomer concentration at reaction loci as the polymerization advances. At elevated temperatures the monomer emulsion equilibrates to a two‐phase or three‐phase system. The upper phase is transparent (monomer), and the lower one is blue colored, typical for microemulsion. After stirring such a multiphase system and initiation of polymerization, the initial coarse polymer emulsion was formed. The average size of monomer/polymer particles strongly decreased up to about 40% conversion and then leveled off. The initial large particles are assumed to be highly monomer‐swollen particles formed by the heteroagglomeration of unstable polymer particles and monomer droplets. The size of the “highly monomer” swollen particles continuously decreases with conversion, and they merge with the growing particles at about 40–50% conversion. The monomer droplets and/or large highly monomer‐swollen polymer particles also serve as a reservoir of monomer and emulsifier. The continuous release of nonionic (hydrophobic) emulsifier from the monomer phase increases the colloidal stability of primary particles and the number of polymer particles, that is, the particle nucleation is shifted to the higher conversion region. Variations of the square and cube of the mean droplet radius with aging time indicate that neither the coalescence nor the Ostwald ripening is the main driving force for the droplet instability. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 804–820, 2003     

Hydrogel‐like elastic membrane consisting of semi‐interpenetrating polymer networks based on a phosphorylcholine polymer and a segmented polyurethane

To obtain a hydrogel‐like elastic membrane, we prepared semi‐interpenetrating polymer networks (IPNs) by the radical polymerization of methacrylates such as 2‐methacryloyloxyethyl phosphorylcholine (MPC), 2‐hydroxyethylmethacrylate, and triethyleneglycol dimethacrylate diffused into segmented polyurethane (SPU) membranes swollen with a monomer mixture. The values of Young's modulus for the hydrated semi‐IPN membranes were less than that for an SPU membrane because of higher hydration, but they were much higher than that for a hydrated MPC polymer gel (non‐SPU). According to a thermal analysis, the MPC polymer influenced the segment association of SPU. The diffusion coefficient of 8‐anilino‐1‐naphthalenesulfonic acid sodium salt from the semi‐IPN membrane could be controlled with different MPC unit concentrations in the membrane, and it was about 7 × 10² times higher than that of the SPU membrane. Fibroblast cell adhesion on the semi‐IPN membrane was effectively reduced by the MPC units. We concluded that semi‐IPNs composed of the MPC polymer and SPU may be novel polymer materials possessing attractive mechanical, diffusive‐release, and nonbiofouling properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 68–75, 2003     

Some theoretical aspects on morphology development in seeded composite latexes. I. Batch conditions below monomer saturation

In seeded emulsion polymerization, during the second stage, new interfaces appear and the surface area changes. A thermodynamic equilibrium approach is presented which predicts particle morphology of a whole range of non-spherical particles upon polymer conversion. Simulation takes into account swelling ratio, molar volumes and interfacial tension. As the particle geometry is complex, a new mathematical procedure is detailed.The computed data are useful to discuss either the stability or the instability of the particles morphology. These results must be compared with actual experimental structures.Abreviations and symbols G Gibbs' free energy - reduced Gibbs' free energy - _i interfacial tension - ₁₂ interfacial tension between polymer 1 and polymer 2 - _1w interfacial tension between polymer 1 and water - _2w interfacial tension between polymer 2 and water - r ₁ polymer 1 swollen by monomer 2 sphere radius - r ₂ polymer 2 swollen by monomer 2 sphere radius - r _i interfacial radius - h ₁ sphere 1 distance to minimal section - h ₂ sphere 2 distance to minimal section - h _i interfacial sphere distance to minimal section - sign ofh _i, positive when the interface sphere is on the side of the sphere 2, negative when the interface sphere is on the side of the sphere 1 - A ₁₂ surface between polymer 1 and polymer 2 - A _1w surface between polymer 1 and water - A _1w ⁰ surface between polymer 1 and water before polymerization - A _2w surface between polymer 2 and water - v ₁ volume of the polymer 1 swollen by monomer 2 - v _i volume of the polymer 1 swollen by monomer 2 before polymerization - v ₂ volume of the polymer 2 swollen by monomer 2 - V _p1 polymer 1 molar volume - V _p2 polymer 2 molar volume - V _m2 monomer 2 molar volume - n _p2 polymer 2 number of mole - n _p1 polymer 1 number of moles - n _m21 monomer 2 number of mole in the swollen polymer 1 - n _m22 monomer 2 number of mole in the swollen polymer 2 - n _m2 monomer 2 total number of mole - n _m2 monomer 2 number of mole before polymerization - TGn ₁ polymer 1 swelling rate - TGn ₂ polymer 2 swelling rate - TGn _i maximum number of mole of monomer 2 in polymeri by mole of polymeri - x polymer 2 conversion rate - K, p, q mathematical variables - D, r, a mathematical variables     

Perfluorocyclobutane aromatic ether polymers

Novel polymers containing alternating perfluorocyclobutane and aromatic ether subunits are prepared from aryl poly(trifluorovinyl ether) monomers via the thermal [2π + 2π] dimerization of the trifluorovinyl ether functionality. A model study is described, which probes the nature of the perfluorocyclobutane rings formed during the polymerization reaction. The bifunctional monomer 4,4′-bis(trifluorovinyloxy) biphenyl and the trifunctional monomer 1,1,1-tris(4-trifluorovinyloxyphenyl)ethane are prepared and polymerized to provide thermoplastic and thermoset polymers, respectively. Characterization of the mechanical and dielectric properties of these new polymers is presented. © 1993 John Wiley & Sons, Inc.     

The preparation of hyperbranched aromatic and aliphatic polyether epoxies by chloride‐catalyzed proton transfer polymerization from ABn and A2 + B3 monomers

Hyperbranched polymers consisting of aromatic or aliphatic polyether cores and epoxide chain‐end peripheries were prepared by proton transfer polymerization. AB₂ diepoxyphenol monomer 1 proved to be well suited for the preparation of hyperbranched aromatic polymer 2 by this proton transfer polymerization. The use of chloride‐ion catalysis, rather than conventional base catalysis, for the preparation of polymers from diepoxyphenol 1 offered a unique method to control the ultimate molecular weight of the polymer product through variations of the initial concentration of monomer 1 in tetrahydrofuran. An alternative route to hyperbranched polyether epoxies made use of commercially available or easily prepared aliphatic monomers of the types AB₂, AB₃, and A₂ + B₃. Although these aliphatic polymerizations can be initiated with a base, chloride‐ion catalysis proved most effective for controlling the polymerization. The hyperbranched epoxies were characterized by NMR spectroscopy, gel permeation chromatography, and multi‐angle laser light scattering. Chemical modification of the polymers after polymerization was carried out via nucleophilic addition on the epoxide groups or derivatization of the hydroxy substituents within the hyperbranched polymer structure. Spectroscopic measurements suggested that some such ring‐opened materials may adopt reverse unimolecular micellar structures in appropriate solution environments. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4850–4869, 2000     

Cationic equilibrium ring-opening polymerization of bicyclic monomers and its application to chemical recycling

Spiro orthoesters give poly(cyclic orthoester)s by single ring-opening polymerization in the presence of acid catalysts, and this process undergoes the equilibrium polymerization. We have applied the function of equilibrium polymerization to chemical recycling of polymeric materials. Crosslinked poly(cyclic orthoester)s, prepared by radical additions of poly(cyclic orthoester)s possessing exomethylene groups and dithiols, efficiently decrosslinked to bifunctional spiro orthoesters in the presence of CF₃CO₂H in CH₂Cl₂. The dithiol-linked bifunctional spiro orthoester monomers, prepared by the radical additions of spiro orthoester possessing exomethylene group and dithiols, afforded the corresponding crosslinked polymers in the presence of CF₃CO₂H as a catalyst in bulk. The decrosslinking of the obtained crosslinked polymer proceeded quantitatively to obtain the corresponding bifunctional monomer at room temperature in CH₂Cl₂. Further, an acid-catalyzed reversible crosslinking-decrosslinking of a polymer having a spiro orthoester group in the side chain was carried out. The copolymer obtained by the radical copolymerization of 2-methylene-1,4,6-trioxaspiro[4.6]undecane with acrylonitrile was treated with CF₃CO₂H at −10 °C in CH₂Cl₂ to afford the crosslinked polymer quantitatively. The crosslinked polymer was then treated with CF₃CO₂H at room temperature at a low concentration in CH₂Cl₂ to recover the original polymer.     

Kinetics of high-intensity electron-beam copolymerization of a divinyl urethane and 2-hydroxyethyl methacrylate

The kinetics of the electron-beam-induced copolymerization of di(2′-methacryloxyethyl)-4-methyl-m-phenylenediurethane (DVU) with 2-hydroxyethyl methacrylate (HEMA) were studied. Monomer mixtures containing 1.96–82.8% DVU have been described at dose rates of 1.7–17 Mrad/sec with the use of 270-kV electrons. Based on rates of conversion, gel formation, and intensity-rate data, a kinetic scheme is proposed in accord with a model which undergoes unimolecular termination and for which the copolymerization and gel formation take place in a crosslinked network swollen with monomers. The rate of gel formation is: In[(1 + g)/(1 ? M₂g)] = A (1 + M₂)t, where g is the gel fraction, M₂ is the mole fraction of DVU in the monomer charge, and A is k_pk_i/k_t. Up to 55% conversion, the rate of disappearance of unsaturation for concentrated DVU solutions (M₂ > 0.03) is: In[M_o/M(1 ? M₂g)] = A (1 + M₂t), where M is the total unsaturation. For dilute solutions of DVU, the rate expression for pregel copolymerization simplifies to: In(M_o/M) = A (1 + M₂)t. These results show that at a certain optimum concentration of monovinyl monomer—70% in the present system—both rapid reaction rates and complete copolymerization occur. Because of the inability of gel bonds to undergo polymerization, a limiting conversion is reached for copolymerizing mixtures containing insufficient monovinyl monomer.     

Kinetics of nonideal hyperbranched A2 + B3 polycondensation: Simulation and comparison with experiments

To overcome the deficiency of mean field method in introducing the intramolecular cyclization and the steric effects, the reactive bond fluctuation model was applied to study nonideal hyperbranched A₂ + B₃ polycondensation, which has high sensitivity of gelation to the concentration of monomers, the feed ratio and the reactivity of functional groups. Simulation demonstrated that the mean field theory overestimated hyperbranched polymerization especially at high reaction conversion in the system with low monomer concentration where the intramolecular cyclization and the steric hindrance play crucial influences on molecular weight, molecular weight distribution and gel point (GP). The dependences of GP on the monomer concentration, feed ratio, and the reactivity of groups are clearly shown. We further simulated a specific polycondensation system with aromatic terephthaloyl chloride (TCl, A₂) and 1,1,1‐tris(4‐trimethylsiloxyphenyl)ethane (TMS‐THPE, B₃) (Macromolecules 2007, 40, 6846) using fitting technology, and estimated molecular weight, molecular weight distribution, GPs, and the conformation of hyperbanched polymer. It provides a feasible way to quantitatively understand hyperbranched polymerization with the reaction specificity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Estimation of the Characteristic Ratio kp(f/kt)½ and Its Temperature Dependence in Bulk Polymerization of Vinyl Chloride

According to a reaction scheme which as its main features assumes that polymerization is predominantly in the interior of the monomer swollen polyvinyl chloride) particles and that all the decaying initiator finally contributes to the polymerization within the polymer particles, the ratio k_p (f/k_t)^½ = K (where k_p, k_t are rate constants for chain propagation and chain termination, respectively, within the particles and f is initiator efficiency) has been calculated for bulk polymerization of vinyl chloride at three temperatures. K is found to be markedly larger than the corresponding quantity for homogeneous solution polymerization, e.g., at 50°C it is seven times this latter quantity. The characteristic ratio K shows a marked negative temperature dependence, which corresponds to approximately -4.5 kcal/mole for E_p - (E_t/2), when f is assumed to be independent of temperature. This behavior is quite consistent with a strong gel effect being operative at the site of reaction, i.e., the swollen polymer particles can be taken as equivalent to a homogeneous polymerization system at high conversion.     

Living cationic polymerization of vinyl ethers with a urethane group

To study the possibility of living cationic polymerization of vinyl ethers with a urethane group, 4‐vinyloxybutyl n‐butylcarbamate ( 1 ) and 4‐vinyloxybutyl phenylcarbamate ( 2 ) were polymerized with the hydrogen chloride/zinc chloride initiating system in methylene chloride solvent at ?30 °C ([monomer]₀ = 0.30 M, [HCl]₀/[ZnCl₂]₀ = 5.0/2.0 mM). The polymerization of 1 was very slow and gave only low‐molecular‐weight polymers with a number‐average molecular weight (M_n) of about 2000 even at 100% monomer conversion. The structural analysis of the products showed occurrence of chain‐transfer reactions because of the urethane group of monomer 1 . In contrast, the polymerization of vinyl ether 2 proceeded much faster than 1 and led to high‐molecular‐weight polymers with narrow molecular weight distributions (MWDs ≤ ～1.2) in quantitative yield. The M_n's of the product polymers increased in direct proportion to monomer conversion and continued to increase linearly after sequential addition of a fresh monomer feed to the almost completely polymerized reaction mixture, whereas the MWDs of the polymers remained narrow. These results indicated the formation of living polymer from vinyl ether 2 . The difference of living nature between monomers 1 and 2 was attributable to the difference of the electron‐withdrawing power of the carbamate substituents, namely, n‐butyl for 1 versus phenyl for 2 , of the monomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2960–2972, 2004     

Neodymium Catalyst for the Polymerization of Dienes and Polar Vinyl Monomers

Ziegler–Natta catalysts have played a major role in industry for the polymerization of dienes and vinyl monomers. However, due to the deactivation of the catalyst, this system fails to polymerize polar vinyl monomers such as vinyl acetate, methyl methacrylate, and methyl acrylate. Herein, a catalytic system composed of NdCl₃⋅3TEP/TIBA is reported, which promotes a quasi‐living polymerization of dienes and is also active for the homopolymerization of polar vinyl monomers. Additionally, this catalytic system generates polymyrcene‐b‐polyisoprene and poly(myrcene)‐b‐poly(methyl methacrylate) diblock copolymers by sequential monomer addition. To encourage the replacement of petroleum‐based polymers by environmentally benign biobased polymers, polymerization of β‐myrcene is demonstrated with a catalytic activity of ≈106 kg polymer mol Nd⁻¹ h⁻¹.     

Synthesis of multifunctional polymer containing Ni‐Pd NPs via thiol‐ene reaction for one‐pot cascade reactions

Recently, acid–base bifunctional catalysts have been considered due to their abilities, such as the simultaneous activation of electrophilic and nucleophilic species and their high importance in organic syntheses. However, the synthesis of acid–base catalysts is problematic due to the neutralization of acidic and basic groups. This work reports a facial approach to solve this problem via the synthesis of a novel bifunctional polymer using inexpensive materials and easy methods. In this way, at the first step, heterogeneous poly (styrene sulfonic acid‐n‐vinylimidazole) containing pentaerythritol tetra‐(3‐mercaptopropionate) (PETMP) and trimethylolpropane trimethacrylate (TMPTMA) cross‐linkers were synthesized in the pores of a mesoporous silica structure using click reaction as a novel bifunctional acid–base catalyst. After that, Ni‐Pd nanoparticles supported on poly (styrenesulfonic acid‐n‐vinylimidazole)/KIT‐6 as a novel trifunctional heterogeneous acid–base‐metal catalyst was prepared. The prepared catalysts were characterized by various techniques like FT‐IR, TGA, ICP‐AES, DRS‐UV, TEM, FE‐SEM, EDS‐Mapping, and XRD. The synthesized catalysts were efficiently used as bifunctional/trifunctional catalysts for one‐pot, deacetalization‐Knoevenagel condensation and one‐pot, three‐step and a sequential reaction containing deacetalization‐Knoevenagel condensation‐reduction reaction. It is important to note that the synthesized catalyst showing high chemo‐selectivity for the reduction of nitro group, alkenyl double bond and ester group in the presence of nitrile. Moreover, it was found that the different nanoparticles including Ni, Pd, and alloyed Ni‐Pd showing different chemo‐selectivity and catalytic activity in the reaction.     

1,3-二(炔丙基氧)苯与4,4'-二叠氮甲基联苯的聚合反应及聚合物性能的研究

研究了1,3-二(炔丙基氧)苯(BPOB)与4,4'-二叠氮甲基联苯(DAMBP)的本体聚合行为. 核磁共振氢谱(¹H NMR)表征了聚合物的结构, 通过傅立叶红外技术(FT-IR)观察了反应过程中的基团变化情况, 采用差示扫描量热技术(DSC)研究了聚合反应动力学, 在较低温度(80 ℃)下二元叠氮与二元炔发生了1,3-偶极环加成聚合反应, 生成了主链含三唑环的聚合物; 利用Kissinger法和Crane法处理得到了反应的动力学参数: 反应级数为0.92, 反应活化能E_a为79.8 kJ• mol^－1, 频率因子A为1.26×10¹⁰ min^－1. 利用凝胶渗透色谱(GPC)、动态热机械分析(DMA)和热重分析方法(TGA)研究了聚合产物的性能. 结果表明, 聚合物的数均分子量达4.22×10⁴, 聚合物有较高的玻璃化转变温度和良好的热稳定性, 玻璃化转变温度达到131 ℃, 热分解温度(T_d5)达355 ℃     

Electrochemical and chemical polymerization of acrylamide

The electrochemical and chemical polymerization of acrylamide (AA) has been studied. The electrolysis of the monomer in N,N-dimethylformamide (DMF) containing (C₄H₉)₄NClO₄ as the supporting electrolyte leads to polymer formation in both anode and cathode compartments. The cathodic polymer dissolves in the reaction mixture and the anodic polymer precipitates during the course of polymerization. A plausible mechanism for the anodic and cathodic initiation reaction has been given. The chemical polymerization of acrylamide that has been initiated by HClO₄ is analogous to its anodic polymerization. The polymer yield increases with an increase in concentration of the monomer and HClO₄. Raising the reaction temperature also enhances the polymerization rate. The overall apparent activation energy of the polymerization was determined to be ca. 19 kcal/mole. The copolymerization of acrylamide was carried out with methyl methacrylate (MMA) in a solution of HClO₄ in DMF. The reactivity ratios are r₁ (AA) = 0.25 and r₂ = 2.50. The polymerization with HClO₄ appears to be by a free radical mechanism. When the polymerization of acrylamide is carried out with HClO₄ in H₂O, a crosslinked water-insoluble gel formation takes place.     

Theoretical study of chain transfer in anionic polymerization. Transfer by the mechanism of side-group substitution

A new theoretical consideration of chain transfer to monomer in the anionic polymerization of hydrocarbon monomers is presented. It is shown that the kinetic scheme used in theoretical studies reported previously contradicts the widespread views on the chemical mechanism of carbanionic reactions. It is suggested that the most probable path of the transfer reaction is the proton abstraction from the side group of the monomer; the terminal double bond of the monomer molecule remains unchanged, and therefore the intermediate species can participate in succeeding reactions as a macromonomer. The molecular characteristics of polymer formed in processes with monomer transfer by side-group substitution are determined. At high conversion, the polymer formed in such a process is shown to possess a number-average degree of polymerization, P̄_n, approaching the theoretical value for living polymers, and a P̄_w exceeding it the more the higher the intensity of transfer. Furthermore, it shows a broad molecular weight distribution and a fairly noticeable degree of branching. These results considerably differ from those previously reported.     

Polymerization Kinetics of Water-Soluble N-Vinyl Monomers in Aqueous and Organic Solution

Summary: Free-radical batch polymerization (FRP) of N-vinyl pyrrolidone (NVP) and N-vinyl formamide (NVF) monomers in aqueous solution as well as NVP polymerization in organic (n-butanol) solution has been studied. The differences found in rate of monomer conversion with monomer and solvent choice correlates well with the differences in values of the propagation rate coefficients (k_p) and their variation with monomer concentration measured in independent pulsed-laser polymerization studies, a result demonstrating that a generalized understanding of water-soluble vinyl monomers can be obtained once their k_p differences have been accounted for. A reasonable representation of polymer molecular mass averages and the complete molecular mass distributions for the three systems was obtained by assuming that the rate coefficient for transfer to monomer, polymer, and organic solvent also vary as a function of monomer concentration.     

Tetrabutylammonium Halides as Selectively Bifunctional Catalysts Enabling the Syntheses of Recyclable High Molecular Weight Salicylic Acid-Based Copolyesters

To synthesize high molecular weight poly(phenolic ester) via a living ring-opening polymerization (ROP) of cyclic phenolic ester monomers remains a critical challenge due to serious transesterification and back-biting reactions. Both phenolic ester bonds in monomer and polymer chains are highly active, and it is difficult so far to distinguish them. In this work, an unprecedented selectively bifunctional catalytic system of tetra-n-butylammonium chloride (TBACl) was discovered to mediate the syntheses of high molecular weight salicylic acid-based copolyesters via a living ROP of salicylate cyclic esters (for poly(salicylic methyl glycolide) (PSMG), M_n=361.8 kg/mol, Ð<1.30). Compared to previous catalysis systems, the side reactions were suppressed remarkably in this catalysis system because phenolic ester bond in monomer can be selectively cleaved over that in polymer chains during ROP progress. Mechanistic studies reveal that the halide anion and alkyl-quaternaryammonium cation work synergistically, where the alkyl-quaternaryammonium cation moiety interacts with the carbonyl group of substrates via non-classical hydrogen bonding. Moreover, these salicylic acid-based copolyesters can be recycled to dimeric monomer under solution condition, and can be recycled to original monomeric monomers without catalyst under sublimation condition.