Synthesis Of Star-shaped Poly Research Articles

Synthesis of star-shaped poly(lactide)s, poly(valerolactone)s and poly(caprolactone)s via ROP catalyzed by N-donor tin(ii) cations and comparison of their wetting properties with linear analogues.

In this study, we report the use of N-coordinated tin(ii) cations [L1→Sn(H2O)][OTf]2·THF (1) and [L1→SnCl][SnCl3] (2) (L1 = 1,2-(C5H4N-2-CH = N)2CH2CH2) as efficient ROP catalysts, which, in combination with benzyl alcohol, afford well-defined linear poly(ε-caprolactone) (PCL) and poly(δ-valerolactones) (PVL) via an activated monomer mechanism (AMM). Thanks to the versatility of complexes 1 and 2 as catalysts, star-shaped PCL, PVL and PLA were also prepared using three-, four-, five- and six-functional alcohols. The number of arms was determined by SEC-MALS-Visco analysis. Spin-coated thin layers of linear and selected six-armed polymers were further studied in terms of their wettability to water. Attention was focused on the influence of the composition and structure of the polymers. Finally, to increase the hydrophobic properties of the studied polymers, stannaboroxines L2(Ph)Sn[(OB-(C6H4-4-CF3))2O] and L2(Ph)Sn[(OB-(C6H4-3,5-CF3)2)2O] (L2 = C6H3-2,6-(Me2NCH2)2) were applied.

The synthesis of star-shaped poly(N-isopropylacrylamide) with two zinc porphyrins as the core and end groups via ATRP and “CLICK” chemistry and a photocatalytic performance study

The synthesis of star-shaped poly(N-isopropylacrylamide) with two zinc porphyrins as the core and end groups via ATRP & “CLICK” chemistry and a photocatalytic performance study.

Erratum to: Synthesis of Star-Shaped Poly(N-isopropylacrylamide) via Atom Transfer Radical Polymerization and Its Photocatalytic Oxidation of Rhodamine B

Erratum to: Synthesis of Star-Shaped Poly(N-isopropylacrylamide) via Atom Transfer Radical Polymerization and Its Photocatalytic Oxidation of Rhodamine B

Synthesis of star-shaped poly(methyl acrylate) via ATRP and preliminary evaluation of its reinforcing properties for PVC

Star-shaped poly(methyl acrylate) (PMA) was synthesized using tri(2-bromopropionate) glyceride as the initiator and methyl acrylate as the monomer via atom transfer radical polymerization (ATRP). The structures of tri(2-bromopropionate) glyceride and PMA were characterized by IR, GC-MS, 1H NMR, and 13C NMR. The reinforcing effects of this star-shaped PMA on polyvinylchloride (PVC) in various PMA/PVC blends were evaluated. The results indicated that a blend containing 1% star-shaped PMA exhibits an 18% increase in the elastic modulus and a 10% increase in tensile strength compared to PVC. Moreover, the impact resistance of the blend was 30% higher than that for PVC. The blend also exhibited high thermal stability. SEM images showed that the star-shaped PMA and PVC are highly compatible when blended, which causes the enhanced elasticity of the blend.

Synthesis of star-shaped poly(N-isopropylacrylamide) via atom transfer radical polymerization and its photocatalytic oxidation of Rhodamine B

Zinc(II) tetra-(2-chloropropionylamido) phthalocyanine (TAPcCl) was synthesized as the initiator for atom transfer radical polymerization (ATRP). Using CuBr/tris(2-dimethylaminoethyl)amine as the catalyst system, ATRP of N-isopropylacrylamide (NIPAM) was performed to create a new star-shaped poly(N-isopropylacrylamide) (PNIPAM) with a zinc phthalocyanine core and PNIPAM arms (TAPc-PAM). The structures of the initiator and the polymers were characterized by means of Fourier transform infrared spectroscopy and proton nuclear magnetic resonance. The polydispersity index obtained by gel permeation chromatography indicated that the molecular weight distribution was narrow. The lower critical solution temperatures (LCST) for the TAPc-PAM aqueous solutions measured using the turbidimetry method were increased due to incorporation of the phthalocyanine core and decreased as molecular weight increased. TAPc-PAM possessed photocatalytic activity, a finding that was verified by Rhodamine B degradation in the presence of hydrogen peroxide under visible light. Moreover, the catalytic efficiency was higher at its LCST, which encouraged reuse of the photocatalyst. Open image in new window

Star-shaped Poly(2-oxazoline)s by Dendrimer Endcapping

The synthesis of star-shaped poly(2-ethyl-2-oxazoline) is reported by direct end-capping of the living polymer chains with dendritic multiamines. The end-capping kinetics after addition of a first generation polypropylenimine dendrimer are discussed based on monitoring by size exclusion chromatography, revealing less efficient end-capping with larger poly(2-ethyl-2-oxazoline) chains and increasing dendrimer generation. In addition, it is demonstrated that the solution viscosity and cloud point temperature of the star-shaped polymers are much less affected by chain length compared with their linear analogues.

Synthesis of star-shaped poly(ε-caprolactone) by samarium-based tetrafunctional initiator and its dilute-solution properties

An in situ–generated tetrafunctional samarium enolate from the reduction of 1,1,1,1-tetra(2-bromoisobutyryloxymethyl)methane with divalent samarium complexes [Sm(PPh2)2 and SmI2] in tetrahydrofuran has proven to initiate the ring-opening polymerization of ϵ-caprolactone (CL) giving star-shaped aliphatic polyesters. The polymerization proceeded with quantitative conversions at room temperature in 2 h and exhibited good controllability of the molecular weight of polymer. The resulting four-armed poly(ϵ-caprolactone) (PCL) was fractionated, and the dilute-solution properties of the fractions were studied in tetrahydrofuran and toluene at 30°C. The Mark–Houwink relations for these solvents were [η] = 2.73 × 10−2Mw0.74 and [η] = 1.97 × 10−2Mw0.75, respectively. In addition, the unperturbed dimensions of the star-shaped PCL systems were also evaluated, and a significant solvent effect was observed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 175–182, 2006

Synthesis of star-shaped poly(ε-caprolactone) via ‘click’ chemistry and ‘supramolecular click’ chemistry

The synthesis of star-shaped poly(epsilon-caprolactone) is described via azide-alkyne cycloaddition ('click' chemistry) and via self-assembly of polymeric ligands into [2 x 2] grid-like metal complexes ('supramolecular click' chemistry).

Synthesis of Star-Shaped Poly(ε-caprolactone)-b-poly(dl-lactic acid-alt-glycolic acid) with Multifunctional Initiator and Stannous Octoate Catalyst

Two types of three-arm or four-arm star-shaped hydroxy-terminated poly(ε-caprolactone) (PCL) were successfully synthesized via the ring-opening polymerization of ε-caprolactone (CL) with multifunctional initiator, such as trimethylolpropane (TMP) or pentaerythritol (PTOL), and stannous octoate (SnOct2) catalyst in bulk at 110 °C. The number-average molecular weight of PCL is proportional to the molar ratio of monomer to initiator. 1H NMR spectroscopy of the resulting PCL indicates that it contains a primary hydroxy end group in each arm. The star-shaped PCL with hydroxy end groups can be used as a macroinitiator for block copolymerization with dl-3-methylglycolide (MG) using SnOct2 catalyst in bulk at 115 °C. 1H NMR spectra of the resulting block copolymers show that the molecular weights and the unit compositions of the block copolymers were controlled by the molar ratios of MG monomer to hydroxy groups of PCL and MG to CL in feed, respectively. Moreover, the molecular weights of the resulting block copolymers linearly increased with the increase of the molar ratios of MG to CL in feed. The molecular weight distributions of the block copolymers were rather narrow (Mw/Mn = 1.09−1.26). 13C NMR spectra of the resulting block copolymers clearly show their diblock structures, that is, PCL as the first block and poly(dl-lactic acid-alt-glycolic acid) (dl-PLGA50) with alternating structures of lactyl and glycolyl units as the second block. Therefore, two types of three-arm or four-arm star-shaped diblock copolyesters comprising the first block PCL and the second block dl-PLGA50 were successfully synthesized via the sequential ring-opening polymerization of CL with multifunctional initiator and SnOct2 catalyst and then followed by copolymerization with MG.

Synthesis of star-shaped poly(d,l-lactic acid-alt-glycolic acid) with multifunctional initiator and SnOct2 catalyst

d,l-3-methylglycolide (MG) was successfully polymerized with multifunctional initiator (trimethylolpropane (TMP) or pentaerythritol (PTOL)) and stannous octoate (SnOct2) catalyst in bulk at 110°C. The effects of molar ratios of monomer to initiator, monomer to catalyst and monomer conversion on the molecular weight of polymer were studied. For the homopolymerization of MG with TMP initiator and SnOct2 catalyst, the molecular weight of polymer increases from 6840 to 35 010 with the molar ratio of monomer to initiator (45–450), and the molecular weight distribution is from 1.15 to 1.35. The results indicate that in the homopolymerization of MG, the molecular weight of polymer is proportional to the molar ratio of monomer to initiator and the monomer conversion. The molar ratio of monomer to catalyst has no influence on the molecular weight of polymer at least within the range of 500–4000. 1H NMR spectra of the resulting polymers obtained from the homopolymerization of MG show that the homopolymerization of MG with TMP or PTOL initiator and SnOct2 catalyst produced two types of three-arm or four-arm star-shaped polymers. The bulk ring-opening homopolymerization of MG proceeds through a “coordination–insertion” mechanism and follows the selective acyl–oxygen bond cleavage reaction. 13C NMR spectroscopy indicates that the obtained poly(d,l-lactic acid-co-glycolic acid) (50:50, in molar ratio; d,l-PLGA50) has an alternating structures of lactyl and glycolyl units.

Synthesis of star-shaped poly(vinyl ether)s by living cationic polymerization: Pathway for formation of star-shaped polymers via polymer linking reactions

Star-shaped polymers of isobutyl vinyl ether (IBVE) with a microgel core of an aliphatic divinyl ether (2) were synthesized in high yield on the basis of the living cationic polymerization with the HCl/ZnCl 2 initiating system. GPC analysis demonstrated that linear coupling products (two-armed polymers) and three-armed star polymers formed during the early stages of the linking reaction, and that subsequent coupling reactions between such low molecular weight star polymers gave star-shaped polymers with more arms The number of arms ranged from 5 to 22, which increased with increasing [2] 0 /[P * ] ratio and/or shortening the arm chain.

Synthesis of star-shaped poly(vinyl ethers) with many arms by living cationic polymerization

Synthesis of star-shaped poly(vinyl ethers) with many arms by living cationic polymerization

Synthesis of star-shaped poly(vinyl ethers) with many arms by living cationic polymerization

Star-shaped polymers of isobutyl vinyl ether (IBVE) with many arms (“crew cut” type) have been synthesized by living cationic polymerization using the HCl-IBVE adduct/ZnCl2 initiating system. A short living polymer (DPn ⪇ 30) of IBVE is allowed to react with a large amount of divinyl ether ([divinyl ether]0/[P*] = 10–15) to give soluble star polymers whose number of arms ranged from 40 to 120. The diameter of such “crew cut” star polymers reached ca. 20 nm.