Biobased polyurethanes for construction applications

A review of renewable polyol routes (vegetable oils and polysaccharides), polyurethane formation chemistry, and construction‑relevant performance attributes in foams and coatings.

The review argues that substituting petrochemical polyols with renewable feedstock‑derived polyols can reduce environmental burden while preserving key PU attributes such as durability, chemical resistance, and flexibility.

Vegetable‑oil polyols

Polysaccharide‑based polyols

Foams and coatings for construction

Background and objective

Polyurethanes (PUs) are described as widely used materials spanning adhesives, coatings, and foams, with strong penetration into construction due to mechanical robustness, chemical resistance, flexibility, and processability. The review frames conventional PU production as dependent on non‑renewable feedstocks and motivates biobased approaches as a pathway to reduce emissions and resource constraints while maintaining performance. It further positions biobased PU development within broader sustainability goals and infrastructure material demands

Formation chemistry and structure–property relevance

PU formation is presented through the reaction between diisocyanates and polyols, yielding repeating urethane linkages. The review emphasizes that final material properties depend on both the polyol and polyisocyanate selection, and it notes that biobased routes frequently focus on polyol substitution while keeping diisocyanate chemistry compatible with established processing. Multiple chemical modification routes for renewable polyols are described (e.g., epoxidation and ring opening, ozonolysis, thiol‑ene coupling), primarily to tune hydroxyl functionality and reactivity.

Construction relevance of PU materials

Applications named Adhesives, coatings, foams (with construction relevance)

Property framing Durability, chemical resistance, flexibility, and processability

Core function: Positions PU as a versatile platform for construction material functions.

PU formation reaction (diisocyanate + polyol)

Key linkage Urethane bond formation in a repeating chain structure

Primary control Polyol/isocyanate selection governs network architecture

Core function: Defines the chemistry basis underlying performance tailoring.

Sustainability motivation for biobased PU

Drivers stated Reduced VOC/emissions framing, lowered energy intensity, renewable raw materials

Core function: Provides the rationale for replacing petrochemical polyols with renewable alternatives.

Polyol modification routes (as listed)

Routes described Ozonolysis, thiol‑ene coupling, photochemical oxidation, hydroformylation, ring‑opening/epoxidation pathways

Core function Explains how renewable oils/polysaccharides are chemically adapted into PU‑reactive polyols.

Vegetable oil‑based polyols (castor and soybean examples)

Vegetable oil polyols are described as increasingly used alternatives to petroleum-based polyols, with examples including castor and soybean oils. Castor oil is highlighted as a strong candidate due to hydroxyl functional groups that can support crosslinking. The review summarizes studies reporting foam and coating property changes with modified polyols, including improvements in mechanical strength, thermal stability, and hydrophobicity depending on hydroxyl value and formulation design.

Polysaccharide‑based polyols (cellulose, starch, chitosan)

Polysaccharide routes are presented as an active research area for producing biobased polyols and subsequent PU systems. Cellulose is described as a long‑chain biopolymer offering a bio‑source for foams that may be biodegradable. Starch and chitosan are discussed as candidates for polyol formation and foam production, with reports indicating enhanced thermal resistance and compressive strength under certain processing conditions, including post‑treatment and long‑term thermal stability observations at elevated temperatures.

Castor oil polyols (property anchor)

Modified polyol hydroxyl value 463 mg KOH/g (as stated)

Reported outcomes: Tensile strength 81 MPa, Tg 124 °C, “good optical properties” (context-specific)

Core function: Illustrates how increased hydroxyl functionality and crosslinking can raise mechanical and thermal metrics.

Soybean‑oil derived polyols (epoxidation/ring-opening)

Route described Epoxidized soybean oil modified to polyol for waterborne PU

Reported trend Increased hydroxyl value associated with higher Tg and higher water contact angle, alongside reduced water absorption (context-specific)

Core function: Links polyol functionalization to hydrophobicity and thermal response.

Starch/chitosan polyols and PU foams

Approach described: Acylated starch as polyol; chitosan- or starch-based PU foams

Reported attributes Corrosion resistance, clarity, and antimicrobial activity for a starch-based coating (context-specific); improved compressive strength after heat treatment for certain foams (context-specific)

Core function: Positions polysaccharide polyols as multifunctional routes for foams/coatings.

Cellulose-derived PU and thermal stability

Route described Regeneration-based cellulose approach leading to thermoplastic cellulose PU sheets (as described)

Thermal stability anchors Heating to 175 °C referenced in foam context; thermal resistance up to 200 °C noted after exposure in a reported study (context-specific)

Core function Summarizes cellulose as a pathway toward heat-tolerant and potentially biodegradable PU formats.

Cross‑cutting technical determinants and interpretation constraints

The review treats hydroxyl value and polyol structure as primary determinants of crosslink density, stiffness, and thermal response. Higher functionality can increase mechanical strength and Tg, but may alter processability and brittleness depending on formulation balance.

Property control via polyol functionality and network architecture

Biobased substitution is largely framed through polyol replacement; however, overall performance remains contingent on diisocyanate selection and compatibility. The article notes that isocyanate chemistry can be adjusted (including aliphatic options) to tune flexibility and water resistance.

Isocyanate choice and coupling with biobased polyols

For construction-relevant applications (coatings and foams), water contact angle and water absorption are highlighted as practical descriptors. The review indicates that polyol chemistry and network formation influence moisture uptake and hence durability.

Hydrophobicity, water uptake, and durability in construction contexts

Reported values (e.g., Tg, strength, contact angle, thermal resistance) are drawn from different studies with distinct formulations and test methods. Consequently, cross-study comparisons should be interpreted cautiously unless methods and conditions are harmonized.