Role of Internal Lipids in Hair Health.

Saturated and unsaturated fatty acids make up 85% of the total hair lipid content and are found in the cuticle and cortical cell membrane complex. Although these lipids only make up 2-6% of the hair's overall weight, they play a crucial role in keeping hair healthy, influencing shine, feel, manageability, and strength. The objective of this work was to understand the mechanisms of how these lipids are lost on exposure to external stressors, such as chemical treatments, washing, and UV exposure and to understand how their loss impacts hair strength. The experimental approach was to measure these lipids and oxidation products, lipid peroxides (LPOs) and correlate their loss with fatigue strength measurements. The results show lipids are lost over time by washing, exposure to chemical treatments, such as coloring, and environmental insults, such as UV, and it was confirmed that a mechanism of degradation is via oxidation of unsaturated lipids to form LPOs. In addition, it was shown that replenishment of these lipids is possible by incorporating lipids, such as fatty alcohols (FaOHs), into a gel network with anionic surfactants to create a delivery system that can efficiently penetrate FaOHs into hair and increase internal strength as measured by fatigue.

Sustainable Polyesters Derived from Glucose and Castor Oil: Building Block Structure Impacts Properties.

Using the glucose derivatives isosorbide and glucarodilactone along with a castor oil derivative, 10-undecenoyl chloride, two monomers were synthesized: glucarodilactone undecenoate (GDLU) and isosorbide undecenoate (IU). These monomers were polymerized via acyclic diene metathesis (ADMET) polymerization to yield two homopolymers, P(GDLU) and P(IU), and two copolymers, P1(GDLU-co-IU) and P2(GDLU-co-IU), of similar number-averaged molecular weight and relative composition (51 and 61 kDa, D = 1.8 and 1.4, 46:54 and 52:48 mol percent). Comparison of the physical properties and degradation behavior of these polymers revealed divergent characteristics arising from differences in the nature of the carbohydrate building blocks. P(IU) is more thermally stable and has a lower glass transition temperature (Td = 369 °C, Tg = -10 °C) than P(GDLU) (Td = 206 °C, Tg = 32 °C) and P1,2(GDLU-co-IU) (Td = 210 and 203 °C, Tg = 1 and 7 °C). While all of the polymers were stable in acidic and neutral aqueous conditions, the two analogs containing GDLU hydrolytically degraded in the presence of base. Tensile testing of the systems revealed that both homopolymers are brittle materials while the P(GDLU-co-IU) is more tough. Notably, P1,2(GDLU-co-IU) was found to be a rubbery material with a low Young's modulus (0.020 and 0.002 GPa, respectively), displaying an average elongation at break of 480 and 640%, and shape memory properties.

Mechanochemistry: opportunities for new and cleaner synthesis.

The aim of this critical review is to provide a broad but digestible overview of mechanochemical synthesis, i.e. reactions conducted by grinding solid reactants together with no or minimal solvent. Although mechanochemistry has historically been a sideline approach to synthesis it may soon move into the mainstream because it is increasingly apparent that it can be practical, and even advantageous, and because of the opportunities it provides for developing more sustainable methods. Concentrating on recent advances, this article covers industrial aspects, inorganic materials, organic synthesis, cocrystallisation, pharmaceutical aspects, metal complexes (including metal-organic frameworks), supramolecular aspects and characterization methods. The historical development, mechanistic aspects, limitations and opportunities are also discussed (314 references).

Alternative solvent-free methodologies in the synthesis of pharmaceutical drugs.

Efforts made by chemists to develop more sustainable processes have resulted in a large increase in greener technologies. Because solvents comprise greater than 80% by mass of a pharmaceutical batch process, the incorporation of solvent-free reactions is expected to significantly reduce the quantity of hazardous waste that is generated during these processes. This review highlights a diverse set of solvent-free organic reactions that can be employed in the development of various pharmaceutical drugs.