This review describes recent strategies for synthesizing polymers that are mostly or fully biobased and exhibit a high glass transition temperature.

Monomers structurally resembling lignin were prepared by reacting 4-hydroxybenzaldehyde, vanillin, syringaldehyde, (each bio-available) or ethylvanillin (synthetic) with dibromoethane, yielding dialdehydes CHO-Ar-OCH 2 CH 2 O-Ar-CHO. Condensation copolymerization with tetraols catalyzed by paratoluene sulfonic acid yielded polyacetal ethers with cyclic acetals in the case of di-trimethylolpropane (di-TMP) and spirocyclic acetals in the case of pentaerythritol (PTOL). Number average molecular weights (M n ) were in the range of 10 600 to 22 200, although the insolubility of those polymers based on 4-hydroxybenzaldehyde precluded this measurement. The polymers are thermally robust and exhibit 5% mass loss via thermogravimetric analysis in the range of 307-349 C. Those copolymers based on PTOL displayed glass transition (T g ) temperatures (108-152 C) at least 40 C higher than their di-TMP analogues (68-98 C), highlighting the added rigidity conferred by spirocyclic acetals versus cyclic acetals. Preliminary degradation studies were conducted in dimethyl sulfoxide with 0.5% added aqueous HCl (concentrated or 2 M). Dynamic light scattering confirmed the facile hydrolysis of the polymers.Generally, polymer degradation was faster with a higher acid concentration and copolymers from the PTOL tetraol were more resistant to hydrolysis than those from the di-TMP tetraol.

Water-degradable polyvinyl acetals with high glass transition temperatures (114–157 °C) were made via acetalization of polyvinyl alcohol (PVA) with bioaromatic aldehydes.

The polymerization of biorenewable molecules to polymers with hydrolyzable main‐chain functionality is one approach to identifying sustainable replacements for common, environmentally unsound packaging plastics. Bioaromatic polyacetals were synthesized via acid‐catalyzed acetal formation from dialdehydes and tetraols. Ethylene linked dialdehyde monomers VV and SS were constructed from bioaromatics vanillin and syringaldehyde, respectively. Tetraol monomers included biogenic erythritol (E), along with pentaerythritol (P), and ditrimethylolpropane (D). Four copolymer series were prepared with varying tetraol content: E/P‐VV; E/D‐VV; E/P‐SS; and E/D‐SS. Number average molecular weights (Mn) ranged from 1,400 to 27,100 Da. Generally, the copolymerization yields were inversely proportional to the feed fraction of erythritol (E), implying that tetraols P and D react more readily. The materials were typically amorphous and exhibited glass transition temperatures (Tg) ranging from 57 to 159 °C, suitably mimicking the Tg values of several commodity plastics. The syringaldehyde‐based copolymers exhibited a higher Tg range (71–159 °C) than the vanillin‐based copolymers (57–110 °C). Accelerated degradation studies in aqueous HCl (3 M, 6 M, concentrated) over 24 h showed that degradation (Mn decrease) was proportional to the acid concentration. A one‐year degradation study of E50/D50‐SS (from 50% feed of erythritol) in seawater, deionized water, tap water, or pH 5 buffer showed no Mn decrease; but in pH 1 buffer, the decrease was 40% (18,800 to 11,200). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44089.