Self-healable hydrogels with regulated cross-linking induced thermo-responsiveness (CIT) were prepared from P(N,N-dimethylacrylamide-stat-diacetone acrylamide) P(DMA-stat-DAA), which was synthesized through RAFT copolymerization. The copolymers of P(DMA-stat-DAA) with various compositions were cross-linked by a series of dihydrazide compounds and self-healable hydrogels were prepared without any additional stimulus under neutral conditions. Interestingly, although the copolymer did not show any temperature responsivity, the hydrogels showed thermo-responsiveness with regulated cloud points, which varied with the composition of the copolymer and group ratios of the dihydrazide cross-linkers. With dynamic covalent acylhydrazone bond connections, the hydrogels showed gel–sol–gel transitions regulated by acidity. Also, the gel–sol transition was induced by the addition of excess dihydrazide compounds and the sol–gel transition was triggered by further addition of P(DMA-stat-DAA). The CIT property provided a new method to prepare thermo-responsive hydrogels from non-thermo-responsive polymers, and the catalysis-free self-healable hydrogels with thermo-responsiveness could have great potential applications in areas related to bioscience and biotechnology.

The local fluid structure of a solution consisting of colloid particles and hydrogen bonding(HB) fluid se-parated from pure solvent by a semipermeable membrane was investigated, where the colloid particles and HB fluid serve as solute and solvent, respectively. In this paper, the semipermeable membrane allows the passage of solvent molecules but not solute particles, and therefore, it provides a nano-confinement for colloid particles. The density profiles of the two species near the semipermeable membrane were determined via density functional theory(DFT) for classical fluids. Based on the predicted density profiles under various conditions, the effects of HB strength, func-tionality, total bulk density, density fraction and the size ratio of two species on the fluid structure were discussed. As an application, the osmotic pressures of the system were also presented. It is shown that the local structure and osmotic pressure can be efficiently regulated by these factors due to the competition between the excluded volume interactions and the HB interaction. The present results are expected to be helpful to study the osmotic phenomena and relevant problems on the nanoscale.

We present the pressure tensor of an associating Lennard-Jones (LJ) fluid confined in a spherical cavity of hard wall, where a high-order density correlation has been taken into account. To give the two-body association potential for calculating the pressure tensor, an angle-average of site–site attraction over all orientations of two particles is performed. Furthermore, the classical density functional theory is employed to obtain the density profile of the confined fluid, by which the normal and tangential pressure profiles are illustrated under various conditions to show the dependence of the pressure tensor on the association strength, number of associating sites, radius of cavity, and bulk density. As an application, the corresponding surface tension is calculated. It is shown that under a strong association interaction (both association strength and the number of associating sites are large), the pressure profiles are depleted from the wall of the cavity instead of the oscillatory behavior under a weak association interaction. Such a tendency is mainly determined by the competition between association interaction and excluded volume interaction. Therefore, the aggregation state and related properties of an associating LJ fluid within a confinement of nanoscale can be efficiently regulated by the association interaction.

Cyclization in the hyperbranched polymerization system of ABg type under different solvent conditions is studied by the method of Monte Carlo (MC) simulation. For this purpose, we apply a scheme of “generation” to specify the growth of polymers, by which a set of differential kinetic equations describing the growth of treelike and cyclic polymers are given. The rate constants of inter- and intramolecular reactions are further deduced to perform the MC simulation. As a result, the number of treelike polymers and cyclic polymers, the size distribution of rings, and the weight-average molecular weight are presented. Based on the simulation results, a significant effect of cyclization on the average properties of polymers is found. Furthermore, the dependence of cyclization on the monomer concentration, solvent effect, and functionality is also discussed. It is shown that cyclization is determined by the cooperation of these factors, of which the monomer concentration plays a leading role. It is expected that the present study may offer useful clues for designing related materials.

A series of polymer brushes with degradable poly(caprolactone) (PCL) backbones were synthesized via “grafting onto” approach by combination of the ring-opening polymerization (ROP) and “click” reaction. First, P(αClCL) was synthesized by ROP and then the chloride was substituted by azide group to obtain P(N3CL) backbone; then polymer brushes were synthesized by “click” reaction of alkynyl-PCL (ay-PCL) and alkynyl-PEO (ay-PEO) onto P(N3CL). The products were characterized by gel permeation chromatography (GPC), FT-IR and 1H NMR. Results indicated that the ay-PCL can be grafted onto P(N3CL) backbone quantitatively at 1 : 1 ratio of alkynyl group to azide group and the branch was attached onto each repeating unit because of lower steric resistance and graft density. Also the amphiphilic polymer brushes with various hetero-branches of PEO/PCL ratios were synthesized by one-pot two-step process. The amphiphilic polymer brushes self-assembled into micelles with various PEO/PCL ratios and have potential application in drug loading and delivery.