Synthesis of cross-linked poly(methyl methacrylate) via dispersion polymerization in supercritical carbon dioxide

Cross-linked poly(methyl methacrylate) particles were prepared via dispersion polymerization in supercritical carbon dioxide (scCO₂) using poly(heptadecafluorodecyl methacrylate) (PHDFDMA) and 2,2′-azobisisobutyronitrile as the dispersant and the initiator, respectively. The following chemicals were used as cross-linking agents: ethylene glycol dimethacrylate (EGDMA), 1,4-buthanediol di(meth)acrylate (1,4-BD(M)A), and trimethylolpropane trimethacrylate. PHDFDMA was synthesized by solution polymerization in scCO₂. We investigated the effect of the chemical structure, concentration of the cross-linking agents, reaction pressure, and CO₂ density on the morphology, the polydispersity, and the cross-linking density of polymer particles. The resulting polymer particle was characterized by field emission SEM, differential scanning calorimetry, and thermal gravimetric analysis. The cross-linked PMMA particles is more agglomerate as the cross-linking agent concentration increased and as pressure decreased at constant temperature. Glass-transition temperature (T _g) of the resulting polymer increased as the cross-linking agent increased with temperature and pressure increasing at the same CO₂ density. Decomposition temperature is slightly increased as 1,4-BDA concentration increased. From these results, we can confirm that the thermal stability of the polymer increased as the cross-linking agent and EGDMA is the best cross-linking agent in term of the thermal stability.     

Synthesis of graft polymers with poly(isoprene) as main chain by living anionic polymerization mechanism

The graft polymers [poly(isoprene)‐graft‐poly(styrene)] (PI‐g‐PS), [poly(isoprene)‐graft‐poly(isoprene)] (PI‐g‐PI), [poly(isoprene)‐graft‐(poly(isoprene)‐block‐poly(styrene))] PI‐g‐(PI‐b‐PS), and [poly(isoprene)‐graft‐(poly(styrene)‐block‐poly(isoprene))] PI‐g‐(PS‐b‐PI) with PI as main chain were synthesized through living anionic polymerization (LAP) mechanism and the efficient coupling reaction. First, the PI was synthesized by LAP mechanism and epoxidized in H₂O₂/HCOOH system for epoxidized PI (EPI). Then, the graft polymers with controlled molecular weight of main chain and side chains, and grafting ratios were obtained by coupling reaction between PI^?Li⁺, PS^?Li⁺, PS‐b‐PI^?Li⁺, or PI‐b‐PS^?Li⁺ macroanions and the epoxide on EPI. The target polymers and all intermediates were well characterized by SEC,¹H NMR, as well as their thermal properties were also evaluated by DSC. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of linear and star-shaped phosphorus-containing telechelic polymers via living cationic ring-opening polymerization using a halobenzene/nickel(II) bromide catalyst

This paper reports a living cationic ring-opening polymerization of 2-phenyl-1,3,2-dioxaphosphorinane (a six membered cyclic phosphonite, 1) initiated by a new catalyst system of a halobenzene with NiBr₂. The polymerization proceeded in a living nature to produce a poly(phosphinate) 2. The polymerizations of seven-and five-membered cyclic phosphonites with this catalyst system are also described. The kinetic analysis of the polymerization of 1, initiated with this catalyst system, has successfully been carried out. The difference of the nature in the polymerizations of five-, six-, and seven-membered monomers is discussed. Syntheses of linear and star-shaped telechelic polymers using di-, tri-, tetra-, and hexahalobenzenes as a catalyst component are disclosed.     

Synthesis of water-soluble fullerene-containing vinyl polymers by low-temperature radiation-induced living polymerization

Water-soluble polymers of acrylamide and acrylic acid that contain fullerene (more than 90% C₆₀) have been prepared by the low-temperature radiation-induced living polymerization. In the absorption spectra of these polymers, a monotonically decaying absorption typical of the covalently bound fullerene or its associates is observed in the range 240–700 nm. The radiation initiation of the process allows preparation of high-purity polymers useful for designing medicinal preparations.     

Synthesis of heteroarm star polymers comprising poly(4-methylphenyl vinyl sulfoxide) segment by living anionic polymerization

<正>A series of 3-arm ABC and AA'B and 4-arm ABCD,AA'BC and AA′A″B heteroarm star polymers comprising one poly(4-methylphenyl vinyl sulfoxide) segment and other segments such as polystyrene,poly(α-methylstyrene), poly(4-methoxystyrene) and poly(4-trimethylsilylstyrene) were synthesized by living anionic polymerization based on diphenylethylene(DPE) chemistry.The DPE-functionalized polymers were synthesized by iterative methodology,and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers.The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide(MePVSO) initiated from the in situ formed polymer anion with two or three polymer segments.The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well.Both approaches could afford the target heteroarm star polymers with predetermined molecular weight,narrow molecular weight distribution (M_w/M_n1.03) and desired composition,evidenced by SEC,~1H-NMR and SLS analyses.These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.     

Functional polymers by living anionic polymerization

The application of living anionic polymerization techniques for the functionalization of polymers and block copolymers is reviewed. The attachment of functional groups to polymeric chains of predetermined lengths and narrow molecular weight distributions is described. Carboxyls, hydroxyls, amines, halogens, double bonds, and many other functional groups can be placed at one or two ends in the center or evenly spaced along polymeric chains. Subsequent transformations of the functional groups further contribute to the versatility of such treatments. General methods based on the use, as terminators, of substituted haloalkanes, as well as the addition of living polymers or their initiators to diphenylethylenes, substituted with appropriate functional groups or molecules, are discussed. Another approach, based on the living polymerization of monomers with protected functional groups, is also discussed. It has been used for the preparation of polymers and copolymers with evenly spaced functional groups. The combination of living anionic polymerization techniques with controlled radical and cationic polymerizations is also described. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2116–2133, 2002     

Multifunctional triphenylamine polymers synthesized via direct (hetero) arylation polymerization

The design rules for creating multifunctional organic electronic materials are currently limited. By copolymerizing twisted triphenylamine (TPA) and electron rich dioxythiophene (XDOT) monomers via Direct (Hetero) Arylation Polymerization (DHAP), a set of polymers are obtained that perform as yellow to transmissive electrochromic (EC) films with up to 45% contrast, as well as in electroluminescent (EL) applications, achieving a luminance of ∼450 cd/m² in yellow‐green polymer light‐emitting diodes (PLEDs). In addition, polymerizing TPA with a donor‐acceptor‐donor monomer results in a low‐bandgap polymer that achieves power conversion efficiencies up to 2.5% when blended with PC₇₁BM in conventional organic photovoltaic (OPV) devices. Incorporation of TPA units into the polymer backbone largely breaks any aggregation and ordering in the solid‐state, leading to highly soluble materials that form smooth, reproducible thin films. The TPA unit also serves to break conjugation throughout the polymer backbone, providing precise control over optical and electronic properties through choice of comonomer. These results suggest that TPA copolymers can be useful for achieving multi‐functionality without sacrificing facile solution processability, making them promising candidates for multifunctional devices like dual EC/EL displays. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 147–153     

Synthesis and characterizations of 1,2,3-triazole containing polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization

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.     

In-situ polymer blends via chain transfer living polymerization (CTLP)

In-situ polymer blends of polystyrene (PS)/poly(methyl methacrylate) (PMMA) with controlled and variable different compositions and molecular weights were found to be successfully synthesized by “chain transfer living polymerization (CTLP)” methodology by a combination of size-exclusion chromatographic analysis, differential scanning calorimetry (DSC), UV/Vis and H NMR spectroscopy, and optical microscopic analysis. The PMMAs prepared in tetrahydrofuran (THF) in the presence of polystyrene exhibit highly syndiotactic stereoregularity (over 70 mol-%) and a glass transition temperature over 120°C. A dispersed morphology was found even for blends with over 31 vol.-% of the weight fraction of one component due to the discrepancy in the molecular weights of two components in the PS/PMMA blends. A ternary polymer blend system having PS/PMMA/PS -block- PMMA can be generated by control of the concentration of fluorene as the chain transfer agent in the CTLP.     

Synthesis of polymers containing conjugated dienyl end-groups by means of anionic living polymerization

In order to synthesize end-functionalized polymers with conjugated dienyl groups, living polymeric anions of polystyrene and polyisoprene were allowed to react with 5-bromo-1,3-pentadiene, 1, and 7-bromo-1,3-heptadiene, 2. The reaction of polystyryl anion and/or polyisoprenyl anion with 1 gave polymers whose end-functionalities were 65–80% regardless of the reaction conditions. On the other hand, almost quantitative functionalization was achieved when a large excess amount of 2 was used as a terminator. When 1,1-diphenylalkyl anion and enolate anion derived from t-butyl methacrylate were used, the degree of end-functionality were 70–80% at best. The resulting end-functionalized polymers were characterized by size exclusion chromatography (SEC), ¹H and ¹³C-NMR and thin layer chromatography coupled with a flame ionization detector (TLC-FID). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3464–3472, 1999     

Synthesis and properties of polydimethylsiloxane-containing block copolymers via living radical polymerization

Polydimethylsiloxane (PDMS) block copolymers were synthesized by using PDMS macroinitiators with copper-mediated living radical polymerization. Diamino PDMS led to initiators that gave ABA block copolymers, but there was low initiator efficiency and molecular weights are somewhat uncontrolled. The use of mono- and difunctional carbinol–hydroxyl functional initiators led to AB and ABA block copolymers with narrow polydispersity indices (PDIs) and controlled number-average molecular weights (M_n's). Polymerization with methyl methacrylate (MMA) and 2-dimethylaminoethyl methacrylate (DMAEMA) was discovered with a range of molecular weights produced. Polymerizations proceeded with excellent first-order kinetics indicative of living polymerization. ABA block copolymers with MMA were prepared with between 28 and 84 wt % poly(methyl methacrylate) with M_n's between 7.6 and 35 K (PDI <1.30), which show thermal transitions characteristic of block copolymers. ABA block copolymers with DMAEMA led to amphiphilic block copolymers with M_n's between 9.5 and 45.7 K (PDIs of 1.25–1.70), which formed aggregates in solution with a critical micelle concentration of 0.1 g dm⁻³ as determined by pyrene fluorimetry experiments. Monocarbinol functional PDMS gave AB block copolymers with both MMA and DMAEMA. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1833–1842, 2001     

Metal-complex-bearing star polymers by metal-catalyzed living radical polymerization: Synthesis and characterization of poly(methyl methacrylate) star polymers with Ru(II)-embedded microgel cores

One-pot, spontaneous, and in-situ incorporation of Ru(II) complexes into a microgel (solubilized nanometer-scale network) has been achieved in near quantitative efficiency by a polymer-linking reaction of linear living poly(methyl methacrylate) (PMMA) with a bifunctional methacrylate (ethylene glycol dimethacrylate or bisphenol A dimethacrylate; linking agent) and a phosphine-ligand monomer [diphenyl-4-styryl-phosphine ( 3 ); i.e., CH₂CH C₆H₄ p-PPh₂] in the RuCl₂(PPh₃)₃-catalyzed living radical polymerization. The products were Ru-bearing. PMMA-armed star polymers with a microgel-core that consisted of a copolymer network of the linking agent and 3 . Upon the network formation, the phosphine ligands efficiently encapsulated RuCl₂(PPh₃)₃, thus achieving a polymer catalyst directly from a polymerization catalyst. Colored dark brown-red, the star polymers exhibited UV-vis absorptions originating from the entrapped complex (3.1–7.4 × 10⁻⁵ mol Ru/g of polymer), the incorporation efficiency being close to 100% with respect to the original polymerization-catalyst. Detailed spectroscopic characterization showed the following: an absolute molecular weight of 1.7 × 10⁵ to 1.7 × 10⁶, an arm number of 11–92 arms/polymer, and a radius of gyration of 8–19 nm (in DMF). Direct observation of the individual star molecules in solid state was achieved by transmission electron microscopy (unstained; 2–3 nm dark dots for the core) and atomic force microscopy (semi-circular images). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4966–4980, 2006     

Synthesis and characterization of amphiphilic triblock polymers by copper mediated living radical polymerization

2-Dimethylaminoethyl methacrylate (DMAEMA) and 2-diethylaminoethyl methacrylate (DEAEMA) block copolymers have been synthesized by using poly(ethylene glycol), poly(tetrahydrofuran) (PTHF) and poly(ethylene butylenes) macroinitiators with copper mediated living radical polymerization. The use of difunctional macroinitiator gave ABA block copolymers with narrow polydispersities (PDI) and controlled number average molecular weights (M_n’s). By using DMAEMA, polymerizations proceed with excellent first order kinetics indicative of well-controlled living polymerization. Online ¹H NMR monitoring has been used to investigate the polymerization of DEAEMA. The first order kinetic plots for the polymerization of DEAMA showed two different rate regimes ascribed to an induction period which is not observed for DMAEMA. ABA triblock copolymers with DMAEMA as the A blocks and PTHF or PBD as B blocks leads to amphiphilic block copolymers with M_n’s between 22 and 24 K (PDI 1.24-1.32) which form aggregates/micelles in solution. The critical aggregation concentrations, as determined by pyrene fluorimetry, are 0.07 and 0.03 g dm⁻¹ for PTHF- and PBD-containing triblocks respectively.     

Synthesis of end-functionalized polystyrenes with organosilicon end-capping reagents via living cationic polymerization

The end-functionalization of living polymers with bases (methanol, benzylamine, diethyl sodiomalonate, and sodium methoxide) and organosilicon compounds [X ? Si(CH₃)₃;X ? : CH₂?C(CH₃)COO? , CH₃COO? , CH₂?CHCH₂? , C₆H₅? ] was investigated in the living cationic polymerization of styrene initiated with the 1-phenylethyl chloride/SnCl₄/nBu₄NCl system in CH₂Cl₂ at ?15°C. The four bases and C₆H₅SiMe₃, independent of their structures, were apparently incapable of reacting with the living end and invariably led to polystyrenes with the ω-end chlorine [～ ～ ～ CH₂CH(Ph)Cl] originated from the initiating system. The number-average end-functionality (F?_n) of the chloride, determined by ¹H-NMR, was close to unity (F?_n > 0.9). The presence of chlorine in the polymer was also confirmed by elemental analysis. In contrast, the quenching by the trimethylsilyl compounds with X = methacryloxy, acetoxy, and allyl gave ω-end-functionalized polystyrenes with the corresponding terminal groups (X) for which the F?_n values were close to unity (F?_n > 0.9). The effects of the structure of silyl compounds on end-capping are also discussed. © 1994 John Wiley & Sons, Inc.     

Synthesis of functionalized asymmetric star polymers containing conductive polyacetylene segments by living anionic polymerization

Novel 3-arm ABC, 4-arm ABCD, and 5-arm ABCDE asymmetric star polymers comprising the conductive polyacetylene precursor, poly(4-methylphenyl vinyl sulfoxide) (PMePVSO), and other segments, such as polystyrene, poly(alpha-methylstyrene), poly(4-methoxystyrene), poly(4-trimethylsilylstyrene), and poly(4-methylstyrene), were synthesized by the methodology based on living anionic polymerization using DPE-functionalized polymers. This methodology involves the addition reaction of a DPE-functionalized polymer to a living anionic polymer followed by the living anionic polymerization of MePVSO initiated from the in situ formed polymer anion with two, three, or four polymer segments. The resultant asymmetric star polymers possessed predetermined molecular weights, narrow molecular weight distributions (Mw/Mn < 1.03), and desired compositions as confirmed by SEC, 1H NMR, SLS, and elemental analysis. After thermal treatment, the PMePVSO segment in the star polymer could be completely converted into a conductive polyacetylene segment, evident from TGA and elemental analysis. These asymmetric star polymers are expected to exhibit interesting solution properties and unique microphase-separated morphological suprastructures with potential applications in nanoscopic conductive materials. Moreover, this methodology can afford the target asymmetric star polymers with arm segments varying in a wide range and enables the synthesis of more complex macromolecular architectures.     

New functional poly(N-vinylpyrrolidone) based (co)polymers via photoinitiated cobalt-mediated radical polymerization

The photoinitiated cobalt-mediated radical polymerization enables the synthesis of novel α-functional and α,ω-telechelic polymers. In combination with ring-opening polymerization, it also produces new amphiphilic copolymers which self-assemble into flower-like vesicles in water.