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We simultaneously employed grazing incidence small-angle and wide-angle X-ray scattering (GISAXS and GIWAXS) techniques to quantitatively study the structural evolution and kinetic behavior of poly(3-hexylthiophene) (P3HT) crystallization, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) aggregation and amorphous P3HT/PCBM domains from a bulk heterojunction (BHJ) to a thermally unstable structure. The independent phase separation regimes on the nanoscale (∼10 nm), mesoscale (∼100 nm) and macroscale (∼μm) are revealed for the first time. Bis-PCBM molecules as inhibitors incorporated into the P3HT/PCBM blend films were adopted as a case study of a control strategy for improving the thermal stability of P3HT/PCBM solar cell. The detailed information on the formation, growth, transformation and mutual interaction between different phases during the hierarchical structural evolution of P3HT/PCBM:xbis-PCBM (x = 8-100%) blend films are presented herein. This systematic study proposes the mechanisms of thermal instability for a polymer/fullerene-based solar cell. We demonstrate a new fundamental concept that the structural evolution and thermal stability of mesoscale amorphous P3HT/PCBM domains during heating are the origin of controlling thermal instability rather than those of nanoscale thermally-stable BHJ structures. It leads to a low-cost and easy-fabrication control strategy for effectively tailoring the hierarchical morphology against thermal instability from molecular to macro scales. The optimum treatment achieving high thermal stability, control of mesoscale domains, can be effectively designed. It is independent of the original BHJ nanostructure design of a polymer/fullerene-based solar cell with high performance. It advances the general knowledge on the thermal instability directly arising from the nanoscale structure.

Thermo-sensitive poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAAm-co-AAc)) latex particles were prepared with and without sodium dodecyl sulfate (SDS) surfactant via an emulsion polymerization method. The P(NIPAAm-co-AAc) latex particle sizes were approximately 1.1 microm without SDS addition and the particle sizes were in the nanometer range (59 nm) with SDS at its critical micelle concentration (CMC) of 8 mM. We propose a scheme to demonstrate how the SDS concentration affects the synthesized latex particle size. The lower critical solution temperature (LCST) was hardly influenced by the SDS level but increased with the AAc concentration. The PNIPAAm-co-AAc latex particles were employed as thermo-sensitive drug carriers and 4-acetamidophenol was loaded to study the drug release rates from the nano-gels. The effective drug diffusion coefficients within the nano-gels varied as a function of particle size, AAc content, and temperature. The smaller or AAc-rich hydrogel particles provided sustainable drug release property and have potential use in biomedical applications.

A core-shell copolymer latex with thermal-responsive properties was prepared and its potential application as a vehicle for drug targeting was investigated in this work, where the crosslinked copolymer of N-isopropylacrylamide (NIPAAm) and chitosan was prepared as the core and the copolymer of methacrylic acid (MAA) and methyl methacrylate (MMA) was prepared as the shell. By using soapless dispersion polymerization, the poly(NIPAAm-chitosan) crosslinked copolymer latex was synthesized first. Then the monomers of MAA and MMA were added to continue the reaction to obtain the core-shell copolymer latex. The weight ratio of MAA/MMA and the concentration of shell monomers (MAA and MMA) in the feed of the reaction mixture had been changed to investigate their effects on the particle size, reaction rate, zeta-potential, specific surface area, and surface functional groups of the latex particles. The swelling and thermoresponsive behavior of the film made from these core-shell latices were also studied under different pH values of buffer solution. The model drug (caffeine) could be merged inside the copolymer particles and protected from releasing through the transport process effectively. And the thermoresponsive property of these copolymer particles significantly enhances the ligand (protein) conjugation that shows the potential of the latex being applied on the targeting drug carrier.