Journal of Polymer Science Part A: Polymer Chemistry最新文献

In this work, the effects of weld lines, additives and the degree of QUV weathering on the tensile behavior of a range of high-density polyethylene composites with calcium carbonate, stabilizers and a carbon black/SEBS masterbatch are studied. The degree of weathering is characterized using FTIR-derived carbonyl, double-bond and carbonate indexes based on curve fitting, to allow for the fairer comparison of specimens with and without calcium carbonate. Weld-line specimens exhibited more rapid degradation than that seen in the reference specimens, while the exposed surfaces of the specimens degraded more quickly than the unexposed surfaces. ISO G154 Cycle 1 and Cycle 6 weathering protocols were compared. The additives were found to be effective at decreasing oxidative degradation, albeit with reduced effects at higher loadings and in mixed systems. These findings were mirrored in the mechanical properties of the specimens, with the modified specimens even exhibiting broadly improved properties with increasing aging. Elongation at break was most sensitive to weathering, with increasing degradation with increasing weathering across almost all specimens.

Cationic polymerization is an important branch of polymer chemistry. Traditional cationic polymerization must be carried out in anhydrous and low temperature environment, with harsh operating conditions, high operating costs and high energy consumption. Visible light induced cationic polymerization is simple, environmentally friendly, and low-cost, so it has become a research hotspot of living cationic polymerization. This paper gives an overview of the recent advances (mainly from 2015 to 2023) on visible-light-induced cationic polymerization, with a focus on visible-light-initiated and visible-light-controlled cationic polymerization. On the basis of controlling cationic polymerization to achieve macromolecular reaction engineering, the realization of temporal scale control will be the main development direction in the future.

Water shortage has risen severely in recent years, confronting mankind with a worldwide challenge, especially as the accessible water resources are further limited by diverse contamination. The most widespread industrial process for water treatment is the activated sludge process, in which, however, excessive sludge production has become an enormous environmental problem worldwide. To overcome this problem, hydrogels possess outstanding potential in view of adsorptive removal of contaminants like heavy metal ions, fertilizers, and dyes. In this paper, we report about the synthesis of biobased alginate hydrogel beads along with polyethyleneimine-modified composite hydrogels for water treatment. The adsorption of methylene blue as a positively charged and of congo red as a negatively charged model dye is quantitatively investigated, both separately and in combination. In addition, the pH-dependent adsorption of the dyes is determined. The use of alginate-based hydrogel systems combines several prospects: they are bio-based, inexpensive, easily available to a sufficient extent, sustainable, and are applicable in a broad range of wastewater treatment by its charged groups.

Medical devices often include polymeric components, which contain additives or contaminants that may leach into patients and pose a health risk. Previously, we proposed a mass transport model that conservatively estimates the leaching kinetics and only requires the solute's diffusion coefficient in the polymer, $��D�$, to be specified. Because determining $��D�$ experimentally is time-consuming, we also parameterized empirical models to estimate worst-case $��D�$ values using only the solute molecular weight, $��M_w�$. These models were based on a modest database and were limited to 19 polymers and larger solutes ($��M_w�>�100�$ g/mol). Here, we assemble a much larger database, which enables us to construct more accurate models using a robust statistical approach, expanding the coverage to 50 device-relevant polymers and smaller solutes ($��M_w�<�100�$ g/mol). Then, we demonstrate several applications of these bounds, including modeling the release kinetics. Finally, we observe an interesting phenomenon, a discontinuous drop in $��D�$ of up to 25,000× for solutes with $��M_w�>�50�$ g/mol in glassy polymers. Using molecular simulations and cheminformatics tools, we propose a novel definition of the effective diameter of free volume channels in polymers, and we show that solutes larger than this channel size diffuse much more slowly.

We synthesized regular polyurethanes from the diol having oxazolidone structure (Diol-1) and the aliphatic diisocyanate by typical polyaddition. The results of the structural analysis suggested that the polyurethane having a cyclic urethane structure such as oxazolidone formed a rod-like structure, although the control polyurethane having a chain urethane structure formed a linear structure. The polyaddition of Diol-1 and aliphatic diisocyanate with triol having oxazolidone structure (Triol-1) as a crosslinker also proceeded successfully to achieve corresponding polyurethanes. However, the polyurethanes containing a molar ratio of Triol-1 less than or equal 50% were soluble in high polar organic solvents nevertheless those polyurethanes contained some trifunctional units in the polymer chain. On the other hand, the polyurethanes containing a molar ratio of Triol-1 more than 50% were insoluble in any organic solvents. We hypothesized that the soluble polyurethanes containing Triol-1 formed multi-branched structure and the insoluble polyurethanes formed cross-linking structure. Such structures of polymer chain affected significantly to the thermal properties of the obtained polyurethanes.

The tendency of epoxy resins to form three-dimensional structures can make them brittle, which restricts their use in various applications even if they have great mechanical properties. Due to the expansion of epoxy resin application to electric automotives and aerospace as carbon fiber resistance plastics (CRFPs), it is desirable to synthesize epoxy resins that is more impact resistant. Herein, the synthesis of flexible epoxy resin FMER-F and FMER-J is reported. These epoxy resins were based on bisphenol F and J diglycidy ether. The dimeric fatty acid modified epoxy resins (FMERs) were synthesized by reacting acid anhydride modified epoxy resins (AMERs) with dimeric fatty acids. To obtain thermosetting epoxy polymers, the epoxy resin was mixed with a curing agent and an accelerator and, subsequently, it was cured at a high temperature. The mechanical properties of various epoxy polymers were analyzed to evaluate the change in the performance of the materials. The flexural strength of the composition with 10 parts per hundred resin (phr) of FMER-F increased by 21%. The impact strength of the composition with 30 phr of FMER-J increased by 27%. FMERs were found to be used as toughening agents in epoxy resins and composites because of their ability to enhance mechanical properties.

Three donor-acceptor (D-A) polymers P1–P3 are designed and synthesized, with 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole (FBT) as A and thiophene derivatives as D. All polymers show good thermal stability. The UV–vis absorption spectra show that P1 has too strong aggregation in solution, and it has no obvious temperature-dependent aggregation (TDA) performance, which is also revealed in the variable temperature UV–vis absorption spectra. P2 film shows the same aggregation as in solution, P3 film shows stronger aggregation than that in solution. Polymers P1 and P2 both have strong TDA properties. Organic field effect transistors (OFETs) are prepared based on polymers P1, P2, and P3. OFETs devices prepared with high molecular weight polymers have better performance, and the polymer with 2-nonyltridecyl side chain leads to the highest hole mobility around 0.252 cm² V⁻¹ s⁻¹. The results show that the application of high molecular weight polymers and the selection of appropriate side chains are very important for the charge transport performance of OFETs.

Two thermoplastic polyurethanes (TPUs) based on the same monomers and composition were produced by two different production methods – hand mix batch process and continuous band casting. The soft segment was poly(hydrofuran) (PTHF) with a molar mass of 1000 and the hard segment was made of 1,4-butanediol (BD) and 4,4′-methylene diphenyl diisocyanate (MDI). The hard segment content amounted to 42%. The distinctions in crystallization and thermal behavior and mechanical properties of the two TPUs were ascribed to differences in the hard and soft block length distribution caused by the different production methods. Using thermal fractionation – a series of successive self-nucleation and annealing steps – the minor differences in hard block length distribution could be shown and quantified. The length distribution of the hard and soft blocks of the machine-produced sample was narrower than that of the hand-cast sample. The former with the narrow block distribution showed thicker and mechanically and thermally more stable hard domains. The more uniform block length distribution facilitated crystallization and resulted in improved tensile recovery behavior and elasticity. The second with the broader distribution, however, showed the highest tensile strength at break, which was ascribed to an improved strain-induced hardening of the soft phase.

Biobased furan polymers (BFPs) derived from 5-hydroxymethylfurfural (HMF) are eco-friendly polymers obtained from inedible biomass resources. Modification of such polymers is expected to expand their practical uses. BFPs have furan moieties that can react as dienophiles with maleimide, facilitating well-designed polymer reactions. Herein, we report the preparation of various maleimides using p-maleimidophenylisocyanate (PMPI), which has a highly reactive isocyanate group and a maleimide group, to modify BFP through the Diels–Alder reaction of the maleimide group. Two reactive sites in PMPI exhibit orthogonal reactivity, enabling us to achieve tailor-made modification agents. The T_g values and rheological properties of modified polymers can be tuned according to the structure of maleimide and their reaction conversion, which demonstrates the practical usability of BFP derived from furfural. The strategy proposed herein can be applied to obtain biobased materials with desirable functions and physical properties.

The cover by Nagma Zerin displays Lithium-ions which can conduct through PEO₆ crystals, where two PEO chains wrap around each other to form a cylindrical tunnel-like structure. The anions do not interact with the lithium-ions and sit in between the tunnels. This type of ion conduction moves away from the traditional idea that lithium-ions can only conduct through the amorphous regions of a solid polymer electrolyte. (DOI: 10.1002/pol.20230002)