JOURNAL OF COSMETIC SCIENCE 116 The GPC (Figure 2) analysis indicated a distribution of low-molecular-weight PDO oligomers (Mn = 250) with polydispersity of 1.2. The 13C NMR DEPT analysis was useful in structural eluicidation by confi rming methine, methylene, or methyl carbons in the spectra. The PDO oligomer structures are composed solely of methylene carbons. The PPDO oligomers were made in standard lab or plant batch reactors (heating, cooling, condenser, and agitation) at ambient pressures with no special modifi cations/engineering controls needed to monitor the nonhazardous PDO monomers. Accidental releases or spills of the nonhazardous bio-based PDO can also be handled safely. The polymerization of EO to the PEG polyethers results in residual amounts of EO and hazardous 1,4-dioxane by-product (dimerization to favorable six-membered ring structure). In comparison, GC analysis of the PDO oligomer product shows no 1,4-dioxane by-product since there is no synthetic route to 1,4-dioxane from the PDO monomer. Fatty acid esters made from the bio-based PPDO oligomers (10,11) or petroleum-based PEG oligomers and plant-derived stearic acid were compared (Figure 2). The PEG-8 stearate is produced by reacting the stearic acid with EO under pressure and using engi- neering controls as described earlier. The PPDO-4 stearate was produced in standard lab or plant batch reactors (heating, cooling, condenser, and agitation) at ambient pressures and with no special modifi cations /engineering controls needed. The polyether chains, ethyl versus propyl groups in the latter PEG-8 stearate, and PPDO stearate emulsifi ers resulted in HLBs of ~11.5 versus ~3 (calc), respectively. Higher HLB PDO–based fatty Figure 2. Fatty acid esters made from bio-based or petroleum based oligomers. Figure 3. MALDI of the bio-based PPDO-4/polyglycerin-3 copolymer sesquistearate.

RENEWABLE PDO AND PETROLEUM-DERIVED ALKYLENE OXIDES 117 Table I Green Chemistry Principles of PPDO-4 (Compared to PEG-8 and PPG-4) Principles of Green Chemistry Use of renewable feedstocks Made from bio-based PDO (bio-based PDO made by fermentation of plant-based sugars) Made from petroleum based EO monomer (Petroleum based EO made from oxidation of ethylene BP = -155° F, under pressure) Made from petroleum based PO monomer (Petroleum based PO made from oxidation of propylene, BP = -54° F under pressure) Less hazardous chemical syntheses Nonhazardous PDO monomer feedstock Hazardous EO monomer Hazardous PO monomer PPDO EO and 1,4-dioxane free PEL (8 h TWA) = 1 ppm, exposure limit PEL (8 h TWA) = 100 ppm, exposure limit PEG—Residual 1,4-dioxane, EO Inherently safer chemistry for accident prevention BP = 418F° BP = 51° F BP = 93° F FP = 244°F FP = -20° F FP = -35° F Vapor pressure at 20 = 0.08 mmHg Vapor pressure at 20 = 1095 mmHg Vapor pressure at 20 = 445 mmHg PDO nonvolatile, combustible EO extremely fl ammable, explosive, toxic PO extremely fl ammable, explosive Design for energy effi ciency Reaction of PDO at ambient pressures Reaction of EO under pressure Reaction of PO under pressure