To overcome the high flammability and brittleness of epoxy resins without sacrificing their glass transition temperature (
) and mechanical properties, three epoxy-terminated hyperbranched flame ...retardants (EHBFRs) with a rigid central core and different branches, named EHBFR-HB, EHBFR-HCM, and EHBFR-HBM, were synthesized. After chemical structure characterization, the synthesized EHBFRs were introduced into the diglycidyl ether of bisphenol A (DGEBA) and cured with 4, 4-diaminodiphenylmethane (DDM). The compatibility, thermal stability, mechanical properties, and flame retardancy of the resultant resins were evaluated. Results showed that all three EHBFRs could significantly improve the fire safety of cured resins, and 30 wt. % of EHBFRs (less than 1.0 wt. % phosphorus content) endowed cured DGEBA with a UL-94 V-0 rating. In addition, the increased rigidity of branches in EHBFRs could increase the flexural strength and modulus of cured resins, and the branches with appropriate rigidity were also beneficial for improving their room temperature impact strength and
.
Hyperbranched poly(methylene-bis-acrylamide), poly(bis(
,
-propyl acryl amide)) (HPNPAM) and poly(bis(
,
-butyl acryl amide)) were synthesized by reversible addition-fragmentation chain transfer ...polymerization. HPNPAMs showed lower critical solution temperature (LCST) due to an appropriate ratio between hydrophilic and hydrophobic groups. The effects of reaction conditions on polymerization were investigated in detail. The structure of HPNPAM was characterized by ¹H NMR, FT-IR, Muti detector-size exclusion chromatography (MDSEC) and Ultravioletvisble (UV-Vis). The α value reached 0.20 and DB was 90%, indicating HPNPAMs with compact topology structure were successfully prepared. LCSTs were tuned by
and the pH value of the solution. The change of molecular size was assayed by dynamic light scattering and scanning electron microscope. These results indicated that the stable uniform nanomicelles were destroyed and macromolecules aggregated together, forming large particles as temperature exceeded LCST. In addition, after the cells were incubated for 24 h, the cell viability reached 80%, which confirmed this new dual responsive HPNPAM had low cytotoxicity.
Abstract
Poly(maleic anhydride‐
alt
‐vinyl acetate) (PMV) is used as a fine chemical in the field of biomedical. However, the techniques of PMV preparation have shortcomings like limited yield (
Y
p
...), complex post‐treatment and toxic solvents. Herein self‐stabilized precipitation (2SP) technique which possessed advantages of simple operation and post‐processing, non‐toxic solvent, and surface‐cleaned product is adopted to synthesize low number‐average molecular weight (
M
n
) PMV by tune‐up of reaction parameters. PMV with
M
n
of 2800–39,200 g/mol are successfully achieved. Furthermore, acidolysis kinetics of PMV is investigated centering on effects of
M
n
, acidolysis temperature, and initial concentration. All samples can undergo completely ring‐opening and the equilibrium pH of acidolyzed PMV is related to initial concentration irrelevant to
M
n
and temperature. Carboxylic degree (CD) varying rate and time of reaching equilibrium pH and 100% CD are impacted by
M
n
and temperature irrelevant to initial concentration. Finally, scale inhibition effectiveness of PMV with 2800 g/mol can be up to 53.69%, larger than that of commercial citric acid by about three times. This contribution supplies an easily operational and eco‐friendly process to obtain low molecular weight PMV which can be the scale inhibitor for industry and daily life, providing the quantization basis for hydrophilic functionalization of PMV.
A new water-soluble pyrene-containing fluorescent polymer, 1-{3′-S-poly(acryloyl ethylene diamine hydrochloride)-2′-methyl propionic acid}propionyloxy hexyloxy pyrene (P3) with defined structure, was ...designed and synthesized using the click reaction between thiol and a carbon-carbon double bond. The intermediate products P1 (S-1-dodecyl-S′-poly(N-Boc-acryloyl ethylene diamine)-2′-methyl propionic acidtrithiocarbonate) and AHP (1-(acryloyloxy hexyloxy)pyrene) were prepared via reversible addition fragmentation chain transfer (RAFT) polymerization and Williamson synthesis, respectively. Conjugating AHP with P1, P2 (1-{3′-S-poly(N-butoxycarbonyl-acryloyl ethylene diamine)-2″-methyl propionic acid} propionyloxy hexyloxy pyrene) was synthesized, adopting both the reduction reaction of a trithioester bond of P1 to thiol and the click reaction between thiol and the carbon-carbon double bond of AHP simultaneously. P3 was obtained by the deprotection of the resulting Boc-protected polymer (P2) with aqueous HCl. The experiment results showed that P2 exhibited a bright blue-violet emission band at approximately 387–429 nm. After deprotection, P3 displayed good solubility in water and not only exhibited a blue-violet fluorescence emission band at approximately 387–429 nm in aqueous solution but also had the similar photoluminescent spectra to those of AHP and P2 in dichloromethane. The fluorescence quantum yields of P2 in dilute tetrahydrofuran and P3 in a dilute aqueous solution were 0.44 and 0.39, respectively. This experiment provided a novel insight into the study of water-soluble fluorescent polymers.
A water-soluble fluorescent polymer, 2,7-di}4'-3''-(S-poly(acryloyl ethylene diamine hydrochloride)-2'''- methyl propionic acid)propionyloxy hexyloxyphenyl{-9,9-di(
n
-octyl)fluorene (
P3
) with ...regular and ordered structure, was designed and synthesized with high conversion using click reaction between thiols and carbon-carbon double bonds. Because the S-H bond is relatively weak, thiol groups are subject to rapid oxidation during purification and storage and thereby result in the low conversion in the following click reaction. To circumvent this limitation, the synthesis of thiol groups and click reaction were simultaneously performed in one system (one-pot method). The intermediate products
P1
(
S
-1-dodecyl-
S
'-poly(
N
-Boc-acryloyl ethylene diamine)-2'-methyl propionic acidtrithiocarbonate) and
M2
(2,7-di4-(acryloyloxy hexyloxy)phenyl-9,9-di(
n
-octyl)fluorene) were prepared
via
reversible addition fragmentation chain transfer (RAFT) polymerization and Williamson synthesis, respectively. Then, 2,7- di}4'-3''-(
S
-poly(
N
-Boc-acryloyl ethylene diamine)-2'''-methyl propionic acid)propionyloxy hexyloxyphenyl{-9,9-di(
n
-octyl)fluorene (
P2
) was synthesized with high conversion (83%) by employing a click reaction with
P1
and
M2
as starting materials. Finally, water-soluble fluorescent polymer
P3
was obtained after the deprotection of
P2
.
M2
,
P1
,
P2
and
P3
were characterized by Fourier transform infrared (FTIR) spectrum, nuclear magnetic resonance (NMR), high-resolution mass spectroscopy (MS), gel permeation chromatograph (GPC), UV-Visible (UV-Vis) spectrum, and fluorescence, respectively. The results revealed that
P3
displayed good solubility in water and not only exhibited a blue fluorescence emission band in water but also had a similar photoluminescent spectra to those of
M2
and
P2
in dichloromethane. The fluorescence quantum yield of
P3
in aqueous solution could reach 0.10. In addition, the result of cell cytotoxicity indicates that
P3
has low cytotoxicity and exhibits potential for biomedical applications. This work provides a new insight into the study of water-soluble fluorescent polymer.
A novel coumarin-derived Cu
-selective Schiff base fluorescent "turn-off" chemosensor CTPE was successfully obtained, which showed an AIE effect. It could identify Cu
by quenching its fluorescence. ...The lower limit of detection was 0.36 μM. CTPE can act as a highly selective and sensitive fluorescence probe for detecting Cu
.
This work presents the first example of acid/base-responsive and near-infrared (NIR)-absorbing photocatalysts based on imidazole-anion-fused perylene diimide chromophores. The photocatalysts were in ...situ generated by deprotonation of imidazole-fused perylene diimide under an alkaline environment. NIR (λ = 730 nm, 128 mW/cm2) photoinduced atom transfer radical polymerization (ATRP) was implemented, exhibiting high efficiency and excellent livingness under ppm level of photocatalysts (15 ppm relative to monomer) and Cu(II) complex (10 ppm relative to monomer) concentrations. The method showed capabilities to polymerize behind opaque barriers (i.e., paper and pig skin) and under aerobic condition. Notably, this work demonstrated a dual temporal control of polymerization by adding weak base/acid and switching NIR light on/off. The polymerization can even be halted by bubbling CO2 and was then fully recovered by adding triethylamine. The NIR photoATRP of acrylamide monomers in aqueous solution was also performed, which can be regulated by the change of pH.
Hyperbranched poly(bis(
N
,
N
-ethyl acrylamide))s (HPNAMs) with many vinyls as terminal groups were synthesized successfully using reversible addition fragmentation chain transfer polymerization ...(RAFT). Detailed analyses, based on the molecular weight,
α
value, degree of branching (DB), and lower critical solution temperature (LCST) obtained from nuclear magnetic resonance (NMR), multi detector-size exclusion chromatography (MDSEC), ultravioletvisible (UV-vis) spectroscopy, and dynamic light scattering (DLS), indicate that we acquired backbone-temperature and pH responsive HPNAM. Factors, such as DB, molecular weight, and pH value, that affect the LCST were investigated. It was found that the molecular weights of the hyperbranched polymers show significant influence on the LCSTs. For the HPNAMs with low molecular weight, the LCSTs decreased as the DB increased, and the LCSTs can also be adjusted by changing the pH value of solutions. Furthermore, the result of cell cytotoxicity indicates that this new dual responsive hyperbranched polymer has low cytotoxicity and exhibits potential for biomedical applications.
Development of highly filled nanocomposites with simultaneous enhanced properties in mechanical properties, anti-ablation and inflaming retarding is still a challenge. In this study, halloysite/ ...phenol-formaldehyde (Hal/PF) composites with different filling rate (10, 20, 30, 40 and 50%, g/g, Hal/PF) were prepared. Hal can achieve good dispersibility even at highest filling rate, in which the tensile strength increases by 39%. The ablation performance tests indicate that the linear ablation rate decreases by 23% as compared to PF resins without the addition of Hal. Moreover, the formation of ceramic-like particles has been confirmed based on the characterizations of XRD, SEM, TEM mapping and Raman spectrometer. Cone calorimetry and vertical combustion tests show that the Hal/PF composites exhibit reduced combustion, retarded fire spread, reduced harmful gas production, lowered fire risk and reduced combustion degree. The as-prepared Hal/PF composites with simultaneous enhanced properties in stretching, impact, anti-ablation and inflaming retarding may provide more room to enrich the family of PF composites and extend their potential application in heat protection field.
Display omitted
•Halloysite was incorporated into PF matrix with good compatibility.•Mechanical, anti-ablative and inflaming retarding properties were enhanced.•Formation of ceramic-like particles has been confirmed.
PDF
